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Chapter 7: The Kitchen utensils

The laws of kitchen utensils and appliances

Introduction:                                                                       Without doubt, the most relevant, and popular, application of the laws of Basar Bechalav is within the Jewish kitchen. The eating of meat and dairy meals necessitates proper separation between the various kitchen items, in order to avoid any forbidden mixtures of meat and dairy. In this chapter we will explore the detailed laws of separation and designation, in terms of the vessels and appliances that are to be separate and designated for only meat or only milk use, and not both interchangeably, and those to be designated as Pareve.   The issue with sharing vessels between meat and dairy: In general, the goal of maintaining separate vessels is to prevent a mixture of meat and milk from occurring to the food, and prevent the Treifing of a vessel. For example, if a dairy vessel contains dairy residue due to an improper cleaning, and one then uses it for meat, the meat then carries dairy substance and is prohibited from being eaten in its current state. Furthermore, even if the dairy vessel is clean, if it absorbed the taste of dairy through heat or soaking [i.e. Kavush], it can now transfer that taste to the meat food and prohibit it, once again through heat or soaking. In the same way, the vessel can absorb the taste of meat and become Treif due to containing a mixture of both meat and milk taste in its walls. Furthermore, even if the dairy vessel is clean and does not contain dairy taste, perhaps it will not be cleaned properly from the meat use, and will be then used for milk products, and we once again return to the original problem.   What items must be designated for separate uses? By certain items, the separation, and prevention of using an item for both meat and milk, is required from the letter of the law. Meaning, that if one were to use the item for meat and milk, interchangeably, the item and food would become forbidden due to Basar Bechalav [i.e. pots]. In other cases, this matter is required from the letter of the law as an initial stringency, even though after the fact the food and vessel may remain Kosher [i.e. knives]. In other cases, it is not required at all, and is customarily done as an act of extra scrupulous observance of the laws [i.e. cups].   Letter of law versus custom: As we will discover, many cases in truth fall under the third category mentioned above, in which sharing and interchanging the item between meat and milk is permitted. Although, in these cases, one may technically share the vessel interchangeably between meat and dairy, nonetheless, the Jewish custom is to avoid doing so in order to prevent possible complications that can develop when sharing its use between meat and milk. This is the reason for majority of the separations of vessels that we follow today in the Jewish kitchen; to keep it simple, uncomplex, and avoid the possibility of questions arising.[1] One should not be lenient or swerve from this cherished tradition, and therefore, whenever we state that something is permitted from the letter of the law, one is to initially strive to perform the accustomed tradition followed today, as will be pointed out. Nonetheless, being that from the letter of the law there is no issue with sharing these items, therefore in a time of need one may be lenient.   Important note: Many of the laws brought here are based on the fine and complex detailed laws of Taaruvos Basar Bechalav, which are explained in the next chapter. Thus, to receive a better understanding of the various requirements discussed in this chapter, it is imperative upon the reader to become well versed with the rules and laws of meat and milk mixtures and what constitutes a Halachic problem.

 

1. General rules and directives:

A. Purchasing/renting a home or renovating a kitchen:[2]

Prior to purchasing or renting a home, one is to examine the kitchen to verify that it contains all the separations accustomed to be followed, such as separate sinks for meat and dairy, separate counters, and the like. Upon building or renovating a kitchen, one should become well versed in the laws below in order to detail its structure in the most Mehudar way possible, which would include separate counters, ovens, stoves, dishwashers, for both meat and milk, and have them situated in opposite ends of the kitchen. 

Verifying Kashrus state of previous owners-Hotel, Tzimmer: Upon purchasing or renting a home from a previous buyer/renter, one must verify the status of their kitchen. If they are not Jewish, or not observant of Kashrus, then various items in the kitchen require Koshering, such as the counters, sinks, ovens, stove tops. If any of the above items are not Kasherable, then proper steps must be taken to ensure a Kosher use of the item. Even when purchasing/renting from orthodox Jews, one should verify the status of the various appliances and whether they have been designated for dairy or meat. There is no need to Kosher the kitchen used by a previous orthodox Jew, even if they may follow other Hashgachas that one would not normally eat, unless the Hashgacha is known to be completely unreliable for one’s standards [such as Rabbanut products of Heter Mechira and the like].

 

 

B. May one Kosher a meat vessel to use for dairy or vice versa?[3]

Through Libun:[4] It is permitted to Kosher a vessel through Libun, and interchange its use between meat and dairy. Thus, one may Kosher a meat oven to use for dairy and vice versa.[5] [All vessels made of earthenware, or other non-Kosherable materials, are only valid if they are Koshered through Libun, even when Koshering from meat to dairy or vice versa.[6] However, vessels made from Kosherable materials, only require Hagala when Koshering from meat to dairy or vice versa, and this applies even if they absorbed meat or dairy without liquid.[7] Nonetheless, using the method of Hagala to switch uses remains restricted, as explained next, while doing Libun to the vessel would be allowed even initially.]

Through Hagala: Some Poskim[8] rule that the custom of the world is to avoid Koshering an item through Hagala for the sake of switching its use from meat to milk vessels, or vice versa. Other Poskim[9], however, rule that it is completely permitted to Kosher a vessel from meat to dairy or vice versa. Practically, the Ashkenazi[10] custom is to be stringent not to do so, unless one of the following exceptions apply:[11] [The above is only initially followed. However, Bedieved, everyone agrees that if it was already Koshered and used for the opposite food, one may continue with its current use.[12]]

The exceptions for Hagala:

1. Time of need:[13] In a time of need, one may Kosher a vessel from meat to milk, or vice versa.
2. Twelve months or does not remember status:[14] If twelve months have passed since the vessels last use, then it may be Koshered from meat to dairy, or vice versa.[15] [Likewise, if the vessels have not been used for a very long time, as often happens with items left in storage, and one no longer remembers the status of the vessel, one may Kosher them and designate them for whatever use one desires.[16]]
3. Koshering for Pesach:[17] When Koshering meat or dairy Chametz vessels for Pesach use, one may now choose to designate them for the opposite food, whether dairy or meat.
4. Koshering from Treif:[18] If a vessel became Treif, after Koshering it, it is permitted to designate it for whatever use one desires. Furthermore, it is even initially permitted to Treif up a vessel in order to be able to then Kosher it and switch its use from meat to milk, or vice versa. [One may prohibit the vessel through cooking some of the opposite food in it while the vessel is not Ben Yomo. However, it is Biblically forbidden to cook meat or milk in it while the pot is Ben Yomo from the opposite use, unless the meat is poultry.[19]]
5. Koshering to Pareve:[20] It is permitted to Kosher a meat or dairy vessel to Pareve. Furthermore, one may then later choose to designate this Koshered vessel for milk/meat. Thus, if after Koshering the vessel, one first uses it for Pareve for some time, it is then permitted to designate it for meat or dairy.
6. Received from another:[21] If one received a meat or dairy vessel as a present, or purchased a meat or dairy vessel from another, it is permitted to Kosher it prior to its initial use, if one desires to use it for the opposite food. Thus, if one inherited his mothers’ pots, he can decide to Kosher the pots and then designate them for whatever use he sees fit.

C. Koshering a vessel that became forbidden due to Basar Bechalav:

In all cases that a vessel has become forbidden due to forbidden use of meat and dairy, it must be verified that the vessel is of a Kosherable material. If it is of Kosherable material, then it may be Koshered through Hagala, or Libun Kal, or Libun Chamur, depending on how it became forbidden.^[22] It is beyond the scope of this book to go through the detailed laws of Koshering, and in case of doubt, a Rav is to be contacted. Much of the laws of Koshering [vis–a-vis Pesach] have been published in our Sefer “The Laws of Pesach” chapter 9-See there!

D. The status of a vessel that has not been used for 12 months:

Some Poskim[23] rule that after 12 months, the taste absorbed in the walls of a vessel becomes nullified. Other Poskim[24], however, rule a vessel remains forbidden forever due to its absorbed taste, even after 12 months. Practically, in a case that one is in doubt as to the status of the vessel, there is room to permit designating it for meat or milk so long as 12 months have passed.[25] Nonetheless, it is best to Kosher the utensils beforehand, [especially if it is made of Kosherable material]. If it is made of non-Kosherable material [i.e. porcelain], then it should be immersed three times in the Hagala waters.[26]

E. If one is in doubt as to whether a certain vessel is dairy, meat, or Pareve, what is the law?

If one is unsure as to a vessel’s dairy or meat status, and 12 months have not passed since its last use, then it is required to be Koshered if one desires to use the vessel for dairy or meat foods.[27] If one does not desire to Kosher the vessel, or it is unable to be Koshered, it may only be used for Pareve foods. If Pareve food is cooked in this vessel [i.e. a pot] then if it does not contain a Davar Charif, the food may be eaten together with dairy or meat in the same meal. If it contains a Davar Charif, it may not be eaten within a meat or dairy meal.[28]

If 12 months have passed: Some Poskim rule that after 12 months the taste absorbed in the walls of a vessel becomes nullified, as stated in the previous Halacha. Accordingly, in a case of doubt as to the status of the vessel, there is room to permit designating it for meat or milk so long as 12 months have passed.[29] Nonetheless, it is best to Kosher the utensils beforehand, [especially if it is made of Kosherable material]. If it is made of non-Kosherable material [i.e. porcelain] then it should be immersed three times in the Hagala waters.[30]

Glass vessels: If one is unsure as to a glass vessel’s dairy or meat status, one may designate it for whatever food one desires, meat or dairy.[31] Nonetheless, if the vessel is a Pyrex pot or baking pan, it is proper to have Hagala performed to it three times prior to use.[32]

F. Color designations for meat and dairy vessels:

The custom of all Jewry is to make a sign of designation on the dairy vessels in order to distinguish the meat and dairy vessels from each other.[33] [It is customary to use blue colors for identification of dairy utensils, and the color red for identification of meat utensils. There is no set color for Pareve designation, although many use the color yellow.]

G. Pareve vessels:

Many are accustomed to have a set of vessels or appliances designated as Pareve in order to allow the foods prepared with those vessels to then be eaten with whatever one desires, whether meat or dairy. Care must be taken to ensure that the vessel remains Pareve by preventing meat or milk from coming into contact with it. Thus, one is not to use the vessel for meat or milk, and is to use only Pareve vessels to enter and remove food to and from the vessel.

Washing Pareve vessels: One  is to have separate sponges for the sake of washing Pareve vessels, and is never to leave the Pareve vessel together with the dirty meat or dairy utensils.[34] [Nevertheless, in a time of need, one may use a dairy or meat sponge to clean a Pareve knife or other utensil, so long as one makes sure that the sponge is clean of any residue, and he does not use hot water.]

If a Pareve vessel was used with meat or dairy: If a Pareve utensil came into contact with meat or dairy, it nevertheless remains Pareve if everything was cold and did not remain in contact for 24 hours. If, however, the meat/dairy was hot, or soaked in the vessel for 24 hours, then the vessel loses its Pareve status. Regarding if a Pareve knife was used to cut a Charif food that was cut with a meat/dairy knife-See Chapter 5 Halacha 3 in Q&A!

2. The appliances and kitchenware:

*Listed in alphabetical order

Blender:

See the section on “Knives & Appliances that contain blades”

 

Bottles [Baby]:[35]

Baby bottles used for cold and hot dairy drinks, or hot and cold meat drinks, are to be separately designated for dairy and meat use, and contain separate brushes for their cleaning.

Cabinets and drawers:[36]

Initial custom: Traditionally, a Kosher kitchen contains separate cabinets and drawers for meat and dairy vessels. While there exists no law that obligates such a distinction[37], doing so is imperative to prevent mix-up of meat vessels being used for dairy and vice versa. Each cabinet or drawer is to have written on it its status of meat or dairy. This especially applies in commercial kitchens, and home’s which contain many family members, visiting relatives, and guests. Various creative forms of identification can be used, such as a blue versus red color sticker, or a sign with a picture of meat versus milk, that can blend well with one’s home decor. A great idea is to set up the dairy and meat cabinets in opposite sides of the Kitchen, each one near their corresponding meat or dairy sink and counter.

Storing in same cabinet/drawer: If one only has a single drawer or cabinet available for use, then separate shelves or sides are to be designated for meat and milk, and they should never be mixed together due to the potential confusion that this can cause. Proper labels are extremely important in such a case so the meat and dairy vessels stick out as such.

Cabinets above stove/oven: It is best to avoid having cabinets above the stove or oven in which food or vessels are stored, as the vapor of the foods that are cooking could potentially contact those foods and vessels. [However, in a time of need, so long as the vapor does not directly hit the food or vessels, it is permitted to be done. In such a case, one is to make sure to keep the cabinets closed during cooking, and to rinse off the pots prior to use.[38]]

Examinations: Commercial kitchens, as well as all household kitchens that contain many people, are to have periodical checks of the drawers and cabinets to verify that the dairy and meat utensils are each found in their designated area.[39]

Pesach cabinet: Pesach cabinets which are used to store one’s Pesach vessels and items are to be properly labeled and sealed off from use. One is not to store any Chametz vessels there due to the possibility of it causing confusion later on if one forgets the items designations.

Cookware and cooking vessels-Pots, pans, spatulas, mixing spoons:[40]

Meat and dairy: It is an absolute Halachic obligation to have separate pots, pans, and their accessories [i.e. spatulas, mixing and serving spoons] for dairy and meat products.[41] If one cooked meat in a dairy pot/pan, or cooked dairy in a meat pot/pan, the vessel is forbidden and must be Koshered, while the food enters into question as to its status [i.e. Ben Yomo versus not Ben Yomo; Charif versus non-Charif]. See Chapter 8 Halacha 20 for the full details of this matter! Likewise if a dairy spatula or spoon was used for meat, the spatula becomes forbidden while the food enters into question as to its status. See Chapter 8 Halacha 24-25!

Pareve:[42] Initially, one is to have separate Pareve pots and pans for foods that one intends to serve for both meat and dairy meals.[43] Thus, for example, a water urn which is used for both meat and milk products, is to be kept Pareve, and one is to specifically purchase an urn for this purpose, rather than heat water in a meat or dairy pot.[44] Bedieved, if one already cooked Pareve food in a meat or dairy pot and one desires to use it for the opposite food-see Chapter 4 Halacha 1 for a distinction in this matter [i.e. Ben Yomo versus not Ben Yomo; Charif versus non-Charif] and a difference between Ashkenazi and Sephardic custom.

Fish pots/pans: It is forbidden due to Sakana to cook fish in a meat pot that contains residue of meat. However, it is even initially permitted to cook fish in a clean meat pot. This applies even if the pot is Ben Yomo.[45] Thus, there is no need to have separate pots for fish. However, some Poskim[46] are stringent to initially forbid cooking fish in a meat pot and hence they require having separate pots for meat and fish.[47] Practically, the widespread custom is to be lenient.[48] However, some are meticulous and designate separate pots for fish and do not to use the meat pots for fish products.[49] [The Hashgacha of Rav Landau in Bnei Brak has separate utensils for fish and meat, including pots, pans, knives, cutlery, grinders, microwaves, and mittens.]

Glass cookware-Pyrex: Glass cookware, such as Pyrex and Duralex, may not be used for meat and milk even if it is cleaned well in between uses, and hence they must be designated as either meaty or dairy just like any other pot. However, some Sephardic Poskim are lenient regarding glass cookware, such as Pyrex and Duralex, to allow cooking meat and dairy one after the other so long as it is cleaned well in between. See the section on “Glass vessels & Cookware” for the full details on this matter!

Pot covers: Just as one may not share pots between meat and dairy foods, so too one may not share pot covers between meat and dairy and Pareve foods/pots. In the event that one placed a dairy cover over a meat pot, and all cases of the like-See Chapter 8 Halacha 21-22!

Industrial steam cookers: See “Steam cookers”

Identification: The pots and pans, and their covers, are to have a sign of their meat or dairy status on them in order to prevent any mix-up from occurring. This especially applies in commercial kitchens, and home’s which contain many family members, visiting relatives, and guests. This can be accomplished through painting the pots and pans with a  blue paint for dairy, and red paint for meat, and so is the protocol of the IDF Rabbinate. Another option is to purchase pots and pans of different shapes and style for meat and dairy.

Counters:[50]

Initial custom: It is proper and customary to have separate counters for both meat and dairy uses.[51] This especially applies in commercial kitchens and homes with large families and guests. Doing so prevents many Halachic issues from potentially arising in the kitchen, and saves one the trouble of constantly cleaning the counter between uses. [Some also have a Pareve counter top which is designated for Pareve use. It is best to initially build the kitchen in a way that the dairy and meat counters are in opposite ends of the kitchen, as explained in Halacha 1A.]

If one only has one counter: In the event that there is only one available counter and one desires to use the same counter for both meat and dairy, one must be careful to wash and clean the counter prior to placing any meat, dairy, or Pareve foods that will be eaten with meat or dairy, on to it. [Experience shows that counter dirt is often camouflaged and blended into the counter color, and hence a mere glance, and apparent clean look, does not suffice. One should therefore wipe the counter area with a sponge and then feel with his hands to verify that in truth no residue has remained.] Likewise, one must be careful to never place hot foods or hot pots directly on the counter.[52] A simple solution to avoid the above hassle is to designate the counter for only one use, whether it be meat or milk [whatever is more common in the household], and purchase a separate counter lining made of PVC, plastic, and the like, to be placed on the counter and used for the opposite food. Another option is to designate half of the available counter space for meat use and the other half for dairy use.

Bedieved if one placed a cold dairy pot on top of a meat counter, or vice versa: If a cold meat pot was placed on a counter that contained cheese, or vice versa, then everything remains Kosher and the pot is to be rinsed with cold water to remove any possible residue of dairy products.

Bedieved if one placed a hot meat pot on top of a dairy counter, or vice versa: If a hot [Yad Soledes] meat pot was placed on a counter that contained dairy residue, then the pot becomes forbidden and requires Koshering, although the food that is inside the pot remains Kosher.[53] If the counter was clean but wet, then that area of the counter becomes Treif and requires Koshering.[54] The pot and food, however, remain permitted unless one knows that this area of the counter absorbed hot dairy within the past 24 hours and the counter was wet.[55] If the counter was clean and dry, and likewise the bottom of the pot was clean and dry, then both the counter and the pot with its food remain Kosher.[56]

Bedieved if one placed a dairy food directly on top of a meat counter: Bedieved, if one placed dairy food directly onto a meat counter, everything remains permitted, so long as the food was cold and the counter was clean, and the food did not soak on the counter for 24 hours.[57] In such a case, the counter requires a mere washing in cold water. If, however, the counter was dirty with meat, then the area of the dairy which contacted the food must be washed or peeled off.[58] If the food contains liquid [i.e. milk] and it remained on the counter for 24 hours, then the counter is forbidden and needs to be Koshered.[59] If the counter was clean but the dairy food was hot, then if the food was a Keli Rishon, or Iruiy Keli Rishon, then the counter is forbidden[60] while the status of the food is dependent on whether the counter was Ben Yomo or not.[61]    

Cut a Charif food on a meat counter: See Chapter 5 Halacha 3 in Q&A!

Chinaware & Cutlery [i.e. Spoons, forks, plates, bowls]:[62]

*This Halacha does not apply to knives which is discussed under its own section called “Knives” and retains a more stringent ruling!

It is an absolute Halachic obligation to have separate chinaware and cutlery [i.e. spoons, forks] for dairy and meat products.[63] One is to have two sets of vessels even if one plans to only use the vessel for cold meat and cold milk products.[64] It is also proper to have a Pareve set of utensils for those foods which one desires to eat with both meat and dairy. This necessity of having two sets of eating vessels is with exception to glass materials, as explained below!

Identification:[65] The plates, bowls, forks, and spoons are to have a sign of their meat or dairy status on them in order to prevent any mix-up from occurring. This especially applies in commercial kitchens, and home’s which contain many family members, visiting relatives, and guests. This can be accomplished by purchasing chinaware and cutlery of different styles for meat and dairy. If the vessels are identical, then the dairy utensils are to have some kind of sign on them to distinguish them from the meat utensils.[66] [In the IDF, all dairy cutlery have a hole perforated into their handle, thus distinguishing them from the meat cutlery.]

Glass plates and bowls: The custom is to use glass plates, bowls, and cups for both dairy and meat foods, even if the foods are hot when poured into the glass, so long as the glass is cleaned well in between uses.[67] Nevertheless, some Poskim[68] are stringent and rule that Ashkenazim are to be stringent with glass vessels and not switch their use between meat and dairy. Practically, the widespread Ashkenazi custom today amongst many, is to initially be stringent and designate separate glass vessels for both meat and milk.[69] However, those who are lenient may continue their custom.[70] Sephardim, however, are customarily lenient in this even initially.[71] [The above only refers to vessels made of actual glass, however, vessels that are made of other materials and simply contain a glass glaze, such as chinaware, are viewed just as any other vessel which require separation between meat and milk for all Jewry.[72]]

Time of need: One is to avoid eating even cold meat with dairy utensils, or cold cheese with meat utensils, even on occasion, even if the plate is clean and one plans on washing it after its use.[73] However, in a time of need that no other plate or spoon/fork is available, one may use a clean meat vessel for cold dairy foods, and vice versa, so long as one makes sure to wash it properly before and after its use using cold water. This applies whether the food is dry or moist, and applies even if the vessel has been used for hot meat or dairy foods in the past, and even if it is made of non-Kosherable material.[74] One, however, may never use the vessel for hot meat/cheese, unless the vessel itself has never been used before for hot cheese/meat, and has never been washed with hot cheese/meat, or had dairy/meat soak in it for 24 hours, in which case the vessel is considered Pareve.[75] It, however, will now become meaty/dairy if used with hot food. 

Bedieved-Used with cold food: Bedieved, if one placed dairy food on a meat plate, or used a meat spoon or fork to eat it, everything remains permitted, so long as the food was cold and the vessel was clean and the food did not soak in the vessel for 24 hours.[76] In such a case, the vessel requires a mere washing in cold water. If, however, the vessel was dirty with meat, then the area of the dairy which contacted the food must be washed or peeled off.[77] If one already mixed it into the food and it cannot be washed or peeled off, then everything is forbidden.[78] If the food contains liquid [i.e. milk], and it remained within the meat vessel for 24 hours, then if the vessel was dirty with leftover meat, everything is forbidden unless the milk contains 60x the meat. If the vessel was clean, then although the milk remains permitted, the vessel is forbidden and must be Koshered.[79]

Bedieved-Used with hot food: If the vessel was clean but the dairy food was hot, then if the food was a Keli Rishon, or Iruiy Keli Rishon, then the vessel is forbidden[80] while the status of the food is dependent on whether the plate was Ben Yomo or not.[81]    

Pareve foods: From the letter of the law, it is permitted even initially to eat cold Pareve food with a cold meat or dairy vessel [other than a  knife], and then eat the remainder of the Pareve with the opposite food.[82] However, if the Pareve food is hot, then if one desires for the food to remain Pareve, it is not to be placed on a meat or dairy vessel. Bedieved, if a Pareve food was placed on a clean meat/dairy vessel, the food remains Pareve unless both the food and vessel were hot of a Keli Rishon. See Chapter 4 Halacha 2! If Pareve was cooked in or with a meat/dairy vessel-See Chapter 4 Halacha 1! See chapter 5 for other questionable scenarios involving Charif.

Knives: Regarding whether a meat knife may be used for dairy, or vice versa, and its law of Lechatchilah and Bedieved, see the section on “Knives.”

Cups:[83]

Sharing cups when one is eating meat and the other milk:[84] Two people who are eating, one meat and the other dairy, may not share cups, as food gets stuck to the cups while one is drinking. [This applies even if they are eating on two separate tables, and do not know each other.[85] If, however, they clean their mouths well prior to drinking, then it is allowed.[86] The same applies if the cup is washed in between.]

Using the same cup for meat/milk after washing in between: From the letter of the law, it is permitted even initially to use the same cups for cold drinks in both meat and milk meals, so long as the cups are washed well in between.[87] Nonetheless, the widespread custom is to designate separate cups for meat and milk. This especially applies if the cups are washed with hot water together with meat or dairy dishes, or if one drinks hot dairy or meat products inside, in which case the cup becomes meaty/dairy.

Time of need: If no other cups are available, one may use a clean meat cup for cold drinks during a dairy meal, or vice versa. This applies even if the cup is Ben Yomo from meat/dairy use. However, one is to avoid using it for hot drinks during the meal.[88] After the meal has concluded and one washes his mouth and lips, one may use the cups even for hot drinks

Glass cups: From the letter of the law, glass cups may be used for dairy and meat meals so long as they are washed well in between. They may even be used for hot drinks.[89] Practically, the widespread custom today amongst many is to initially be stringent and designate separate glass vessels for both meat and milk, however those who are lenient may continue their custom.[90]

Pitchers: See the section on “Pitchers”

Q&A May a water bottle from which one drinks directly from its opening be used during both meat and dairy meals? A water bottle from which one drinks directly from its opening [i.e. by placing his mouth on the opening] is not to be used during both a meat and dairy meal unless it is washed in between.

Cutting board:[91]

Cutting boards tend to contain crevices which are formed by the knife and are very difficult to clean.[92] It is thus imperative to have separate cutting boards for the sake of cutting meat, dairy, and Pareve foods. Using the same cutting board for meat and dairy can cause substance of one food to get onto the opposite food. Using a meat/dairy cutting board for Pareve can cause a Pareve food to absorb substance, or even taste [in the case of Charif], of the meat/milk and hence no longer be allowed to be eaten with the opposite food.

Time of need-Meat/cheese:[93] In a time of need, it is permitted to cut meat on a dairy cutting board, or dairy on a meat cutting, so long as the meat and dairy are cold, are not defined as Charif [i.e. salted spiced heavily] and the cutting board has been washed well with soap and water, and examined to make sure it is clean of residue. One may alternatively place a sheet of tinfoil on the cutting board to ensure that no residue that remains will get on the meat/cheese.

Time of need-Pareve/Charif: It is permitted in a time of need to cut Pareve foods on a dairy cutting board even though one intends to eat those foods with meat, so long as the Pareve is cold, is not defined as Charif [See Chapter 5], and the cutting board has been washed well with soap and water, and examined to make sure it is clean of residue. One may alternatively place a sheet of tinfoil on the cutting board to ensure that no residue that remains will get on the meat/cheese. If the Pareve food is defined as Charif, it is absolutely forbidden to cut it on a meat/dairy cutting board with intent to eat it with the opposite food.[94] If the Pareve food is not Charif, but is hot, then this matter is dependent on whether the cutting board is clean and whether or not it is Ben Yomo.

Bedieved: If hot Yad Soeldes meat was cut, or even simply placed, on a dairy cutting board, then the cutting board is forbidden[95] while the status of the food is dependent on whether the cutting board was dirty with dairy residue or was Ben Yomo, in which case it is forbidden a Kelipas worth.[96] If cold, or less than Yad Soeldes, meat was placed on the cutting board, then everything remains permitted while the meat needs to be washed.[97] If cold non-Charif Pareve was cut on a meat cutting board with a Pareve knife, it suffices to simply wash it and it may then be eaten with the opposite food. If Charif was cut with a Pareve knife on a meat or dairy cutting board, according to many Poskim[98] it is forbidden to eat the Charif with the opposite food. In all cases that washing is required and one forgot to do so until after the food was mixed or cooked, it remains permitted.[99]

Dishwashing utensils:

Sponges for washing dishes: Initially, one is to designate separate sponges for washing meat, dairy and Pareve dishes, and so is customary of all Jewry today. See the section on “Sponges” for the full details on this matter!

Dish soap: It is proper to have separate containers of dish soap for both meat and milk in order to prevent residue of food getting onto the container and back onto one’s hands or vessel. However, from the letter of the law, this is not required.[100]

Drying racks:[101] One is to initially invest to have separate drying racks for both meat and dairy vessels. If one is unable to do so, then the drying rack may be used for meat and dairy vessels so long as one is careful of the following: 1) Care is to be taken that only clean utensils are placed there. 2) All the vessels are properly marked and placed in their proper section of meat or milk after they dry. 3) One is to beware not to leave the meat or dairy utensils within each other, and they are to always sit within separate and individualized areas of the rack.[102]

Examinations: Commercial kitchens, as well as all household kitchens that contain many people, are to have periodical checks of the drawers and cabinets to verify that the dairy and meat utensils are each found in their designated area.[103]

Pareve utensils: One is to have separate sponges for the sake of washing Pareve utensils and is never to leave the dirty Pareve vessel together with the dirty meat or dairy utensils.[104] [Nevertheless, in a time of need, one may use a dairy or meat sponge to clean a Pareve utensil. Prior to doing so, one is to make sure the sponge is clean of any residue, and make sure not to use hot water.]

Dishwasher:[105]

Using the same dishwasher for both meat and milk vessels, even one after the other, can cause potential Kashrus concerns. Thus, initially, one is to have separate dishwashers for both meat and dairy utensils and have them connected to separate drainage systems. Initially, even Pareve vessels should not be washed in the meat or dairy dishwasher. If one only has one dishwasher available, it should be designated for only one use [i.e. the more necessary] and have the other dishes washed by hand, and so is the custom of many.[106] Nonetheless, from the letter of the law, it is possible to use the same dishwasher for meat and dairy and Pareve vessels, under the conditions to be explained.[107] One who moves into a home that contains a dishwasher must verify with the owner as to its status. If this is not possible, then it needs to be Koshered.

Time of need-Using the same dishwasher for meat and dairy vessels: One may not use the same dishwasher for washing both meat and dairy vessels at the same time, and one who does so possibly prohibits all the vessels that are in there.[108] However, one may use the same dishwasher for washing meat and dairy vessels one after the other, if the following conditions are fulfilled:[109] 1) The machine is taken apart and cleaned from any and all food residue. 2) The dish wracks are switched[110] or cleaned very well before use. 3) One waits 24 hours from its last use of the opposite dishes of meat or milk. 4) One runs an empty cycle with hot water and soap prior to the current cycle. 5) The above process only helps if the dishwasher does not contain any porcelain or ceramic material inside, otherwise it cannot be Koshered to a different use.[111] However, some Poskim[112] are lenient to use the dishwasher even without Koshering it in-between or waiting 24 hours [steps 3-5].

Bedieved:[113] If one found a dairy vessel in his meat dishwasher which uses Yad Soledes water, then if one does not know for certain that the meat vessels were clean, the dairy vessel is forbidden.[114] [However, the meat vessels remain permitted if one can assume that there were 60x against any dairy residue.] If, however, soap was used throughout the entire period of the hot washing, then many Poskim are lenient to permit all the vessels, as explained in Chapter 8 Halacha 30E. Possibly one may rely on this if he is unsure if the vessels were dirty with meat.[115] Likewise, even if he is positive that there was meat and dairy residue there, some dishwashers may be defined as Iruiy Keli Rishon, and would contain an added leniency. A Rav is to be contacted for final clarification.

Koshering a dishwasher:[116] A dishwasher that has become forbidden due to washing Issur, or meat and milk together, is to be Koshered in the following method if made of Kasherable materials [i.e. metal]: 1) The machine is taken apart and cleaned from any and all food residue. 2) The dish wracks are to cleaned. 3) One waits 24 hours from its last use.[117] 4) Run an empty cycle with hot water at the maximum possible temperature [i.e. Hagala].[118] The above process only helps if the dishwasher does not contain any un-Kasherable materials, such as porcelain or ceramic material inside, otherwise it cannot be Koshered.[119] Most dishwashers today do contain non-Kasherable materials.

Food processor:

See the section on “Knives and appliances that contain blades”

 

Fridge:[120]

It is permitted to use the same fridge for both dairy and meat products. The products may even be placed near each other, and from the letter of the law do not even need to be covered [121] Nevertheless, there are those who are initially stringent to avoid doing so. Practically, it is proper to suspect for this opinion if there is no need to be lenient in this.[122] [If, however, either the meat or milk is covered, according to all there is no need to be stringent.[123] Likewise, if both the meat and dairy are liquids, there is no need to be stringent even if both are uncovered.[124]]

Suggestive practice: The above is all from the letter of the law, however, practically, it is proper to set up the foods in the fridge in a way that prevents meat and milk products from ever coming into contact with each other, such as to have separate shelves designated for them, or having everything in closed containers. One should never leave open meat or dairy liquids in the fridge, as spillage can cause foods and vessels to absorb substance or taste of spilled meat/milk, such as if it sits in the liquid for 24 hours.

Bedieved: If one discovered a spillage of milk on the shelf of one’s fridge, then the foods and vessels are to simply be washed clean. If, however, they remain in this state for 24 hours, it is considered as if the foods/vessels were cooked in the milk. The same applies regarding spilled chicken soup. See Chapter 8 Halacha 7!

Garbage:[125]

It is permitted to throw both meat and dairy foods into the same garbage bag even if they are hot and contain liquid. It is likewise permitted to burn garbage even if one is certain the garbage contains both meat and milk.[126] However, some[127] write that one is not to pour hot milk into a garbage that contains domestic animal meat, or vice versa, due to the Biblical cooking prohibition.

Rinsing and using for food: Being that garbage cans, brooms, and shovels are dirty with both meat and dairy, they are hence not to be washed in the meat or dairy sink. One is also not to use it to store food.

Glass vessels/cookware-May they be used for both meat and dairy products?[128]

The three opinions: 1) Some Poskim[129] rule that glass is a hard and smooth material which cannot absorb the taste of foods and thus does not require Koshering from dairy to meat or from non-Kosher to Kosher. [Accordingly, a glass vessel may be used for both dairy and meat foods even if the foods are hot and are heated within the glass, so long as the glass is cleaned well in between uses. Likewise, a glass vessel of a gentile can be washed well and then used to cook Kosher food. Likewise, one’s glass Chametz vessels can be washed well and used for Pesach. This applies even if they were used for cooking hot Chametz during the year or had Chametz, such as bear, stored in them for long periods of time.[130]] 2) Other Poskim[131], however, rule that glass has the same status as other metal vessels which absorb taste and must hence be Koshered prior to use from meat to milk or Chametz to Pesach. 3) Other Poskim[132], however, rule that glass has the same status as earthenware, and not only does it absorb taste of food, but can never be Koshered. Thus, if a glass vessel was used for hot Chametz, it may not be used during Pesach. Likewise, a glass vessel used for hot meat, may not be used for dairy, and a non-Kosher glass vessel may not be used for Kosher foods.

The final ruling-Using glass plates, cups, bowls for Meat & Milk:[133] Practically, although the custom amongst Ashkenazi Jewry is to be stringent and not Kosher Chametz glass vessels for Pesach[134], regarding other Issurim [non-Kosher foods] they are lenient to use them without even requiring Koshering.[135] Thus, the custom is to use glass plates, bowls, and cups for both dairy and meat foods even if the foods are hot when poured into the glass, so long as the glass is cleaned well in between uses.[136] Nevertheless, some Poskim[137] rule that Ashkenazim are to be stringent with glass vessels and not switch their use between meat and dairy. Practically, the widespread Ashkenazi custom today amongst many is to initially be stringent and designate separate glass vessels for both meat and milk[138], however those who are lenient may continue their custom.[139] Sephardim, however, are customarily lenient in this even initially.[140] [The above only refers to vessels made of actual glass, however, vessels that are made of other materials and simply contain a glass glaze, follow the same laws as a metal vessel, as explained in the Q&A!]

Glass cookware-Heat resistant glass such as Pyrex/Dulerex:[141] Tempered glass which is manufactured to have a high heat resistance and is used to cook with on a fire or in an oven is debated amongst the Poskim as to its status, and whether it has the same laws as the glass discussed above.[142] Some Poskim[143] rule it is more strict than regular glass and is forbidden to be used for cooking or baking of both meat and milk, and it must thus be designated for one food.[144] Other Poskim[145], however, rule it has the same status as all glass and may hence be used by Sephardim on Pesach, and may be used for cooking meat and milk one after the other so long as the cookware is cleaned well in between uses.

 

Summary: Ashkenazim: The Ashkenazi custom is not to use any Chametz glass vessels on Pesach even if they are Koshered. However, glass eating vessels [i.e. cups, plates, bowls] may be used for both meat and milk even if hot, so long as they are well cleaned in between uses. However, glass cookware, such as Pyrex and Duralex, may not be used for meat and milk even if it is well cleaned in between uses. If one did so then the vessel is to be Koshered. Practically, the widespread custom today amongst many is to initially be stringent and designate separate glass vessels [i.e. cups, plates, bowls] for both meat and milk, however those who are lenient may continue their custom. Sephardim: The Sephardic custom is to allow using glass eating vessels [i.e. cups, plates, bowls] for both meat and milk [even if hot] so long as they are well cleaned in between uses. The same applies regarding using glass Chametz vessels for Pesach, or using the glass vessels of a gentile for Kosher food. Some Sephardic Poskim are lenient even regarding glass cookware, such as Pyrex and Duralex, to allow cooking meat and dairy one after the other so long as they are cleaned well in between. Others, however, are stringent.   Glass pot covers: Glass pot covers may not be used for both meat and milk even according to the lenient opinion above, as they contain non-glass parts, as well as are difficult to properly clean. See Chapter 8 Halacha 21 regarding Bedieved!   May a glass vessel that contains a crack be used for meat/milk?[146] No. The above allowance of using glass vessels for both meat and milk products only applies if the glass is smooth, and does not contain any cracks and crevices which definitely absorb and hence give it the same status as any other material vessel.   What is the status of a glazed vessel?[147] The above allowance of using glass vessels for both meat and milk products only refers to vessels made of actual glass, however, vessels that are made of other materials and simply contain a glass glaze, such as chinaware, are viewed just as any other vessel which require separation between meat and milk for all Jewry.

Gloves/mittens:[148]

One is to have a separate set of cooking mittens and gloves for meat and dairy foods in order to prevent possible transference of residue to an opposite pot.  

Grater [Hand grater]:[149]

A grater follows the same laws as a knife [to be explained in its section] and it is thus necessary to have a separate set of meat and dairy graters if one plans on using it to grate cheese or meat. Likewise, it is proper to have Pareve graters which are designated for grating fruits and vegetables. This especially applies when grating Charif vegetables, such as an onion, in order so they can be used for whatever one desires. One may not use a meat grater to grate fruits or vegetables that will be eaten with dairy, and the same applies vice versa.[150] This especially applies if the grated food is Charif. Charif foods that have been cut with a meat or dairy knife [i.e. horseradish cut with meat knife], are not to be grated in a Pareve grater or a grater of the opposite use.

Bedieved: If a meat or dairy hand grater was used to grate a food or vegetable, it is initially not to be used for the opposite food. This especially applies if the grated food was Charif.[151] Bedieved, if the Charif was already used for the opposite food, the food remains permitted.[152]

Juicer [with blades]:[153]

*See the section regarding “Knives” for the full details of this subject!

Juicers are to be designated as Pareve and be maintained as such. Thus, one is to avoid using the Pareve juicer to make milkshakes, or to juice Charif foods that have been cut with a meat or dairy knife [i.e. lemons].

Milk shake mixer-A juicer used with milk: A juicer which is used to make milk shakes is to be designated as dairy and is not to be used for meat, or even Pareve products eaten with meat. In a time of need, it may be used for juicing foods that will be mixed with meat foods if it is properly cleaned. This especially applies to the blades which require special attention to verify their cleanliness.

Kneading accessories:[154]

Kneading utensils [i.e. rolling pins] are to be designated as Pareve and be maintained as such. Thus, one is to avoid using it for dough that contains milk or meat products.[155] Kneading utensils that have been used for dairy dough are to be designated as dairy and not be used for meaty dough, or even Pareve dough that will be eaten with meat. Nevertheless, in a time of need, one may be lenient to use it so long as one verifies its cleanliness beforehand.[156]

Knives & Appliances that contain blades [i.e. blender]:

*The following is a summary of the detailed laws explained below. See there for all sources and background!

The custom of all Jewry is to designate separate knives for milk and meat and to make a mark on the dairy knives to distinguish them from the meat knives. One may not divert from this custom of Jewry. Those who are meticulous are accustomed to have three sets of knives; one for meat, one for milk, and one for Pareve.[157] [Practically, so is to be followed by all in order to allow cut Pareve foods to be used for meat/dairy without issue.[158]]

Letter of law-Cutting meat/cheese: It is initially forbidden to cut meat with a dairy knife, or vice versa, even if the knife is clean and Neitza was performed. In a time of need, such as no other knife is available, it is disputed amongst the Poskim as to whether one may cut meat/cheese if Neitza was performed. See Halacha A-C! Regarding Bedieved-See D!

Letter of law-Cutting Pareve to eat with meat/dairy: The custom is to avoid cutting Pareve foods with a dairy knife if one intends to eat those foods with meat. The same applies vice versa. If, however, no other knife is available, then one may be lenient to use the knife for cutting non-Charif foods after a thorough cleansing. See below B-C! Regarding Charif foods-see chapter 5 Halacha 3. Regarding if a Pareve food was cut with a dirty meat/dairy knife and if it may be used for the opposite food-See Chapter 5 Halacha 2!

A word of advice regarding Charif: Due to the complex Halachic issues that a Charif vegetable poses if it is cut with a meat or dairy knife [and then gets used with the opposite food or vessel], it is highly recommended that every kitchen establish a rule that all Charif vegetables be cut with a Pareve knife and Pareve cutting board. Experience has shown that leaving a meat or dairy cut Charif vegetable around the fridge is bound to create problems, as people forget its status and can come to use it for the opposite food.

Background and detailed ruling:[159]

Knives, as opposed to forks or spoons, carry an extra worry when sharing between meat and milk, as the grooves of a knife tend to collect food residue as a result of the pressure placed on a food upon being cut. Hence, using a meat knife for dairy foods, or vice versa, raises the worry that perhaps some meat residue will now carry onto the dairy food.[160] Accordingly, the Poskim rule that it is forbidden to use a meat knife for dairy or vice versa. This prohibition possibly extends to even if the knife is clean, due to worry that if we allow one to use a clean meat knife for dairy, one may come to forget and use it even when dirty.[161] The Poskim discuss various scenarios of cleaning, and as to what it may allow one to perform [i.e. cutting actual cheese, or cutting only Pareve that will be eaten with cheese], as will be discussed below. An additional issue that knives pose is in the subject of Charif, as explained in Chapter 5.

 

A. The general law:

It is forbidden to cut cheese, or even bread or other Pareve food which one plans to eat with cheese, using a knife which is usually used to cut meat [i.e. a meat knife].[162] The same applies vice versa.[163] Accordingly, the custom of all Jewry is to designate separate knives for milk and meat and to make a mark on the dairy knives to distinguish them from the meat knives. One may not divert from this custom of Jewry.[164] [The above prohibition, however, only refers to a knife that has not been properly cleaned or Koshered. However, if the knife has been properly cleaned [B] or Koshered [C], then the matter is subject to debate amongst the Poskim, and is dependent on whether other knives are available, and as to what one desires to use it for, as will now be explained.]

 

B. If the knife was cleaned but not Koshered [No Neitza]:

Cutting actual meat and cheese:[165] It is forbidden to use a meat knife to cut cheese even if the knife was cleaned.

Cutting Pareve for a meat/dairy meal: Some Poskim[166], rule that it is permitted to use a clean meat knife to cut bread and other [non-Charif[167]] Pareve foods that will be eaten with the cheese. One is not required to perform Neitza to the knife and a simple cleansing suffices. This applies even according to the above custom to designate separate knives for meat and milk, nevertheless, one may even initially[168] use a clean meat knife to cut bread [or other Pareve foods] which he plans to eat with cheese.[169] Other Poskim[170], however, rule that it is forbidden to use a clean meat knife to cut even bread and other foods which will be eaten with dairy, unless Neitza was performed to the knife. Furthermore, due to the custom, one may not use a meat knife to cut Pareve which will be eaten with dairy even if Neitza was performed, unless no other knife is available.[171] Practically, the custom of the world is not to cut Pareve foods that will be eaten with dairy with a meat knife even if clean, however in a time of need one be lenient to do so [even if Neitza was not performed due to inability to do so[172]].[173]

 

C. If the knife had Neitza[174] performed:

Cutting actual meat and cheese: Some Poskim[175] rule that from the letter of the law, if one performed Neitza to a meat knife, it may be used to cut cheese.[176] However, due to the widespread Jewish custom to designate separate knives for meat and cheese, it is forbidden to [initially] do so [unless no other knife is available].[177] Other Poskim[178], however, rule that it is forbidden to use a meat knife to cut cheese even if Neitza is performed, and even if no other knife is available.[179]

Cutting Pareve for a meat/dairy meal: From the letter of the law, one may use a meat knife to cut bread [or other Pareve foods[180]] which he plans to eat with cheese, if Neitza was performed to the knife.[181] Some Poskim[182], however, rule that due to the custom, one may not use a meat knife to cut Pareve which will be eaten with dairy even if Neitza was performed, unless no other knife is available.[183] Other Poskim[184], however, rule that to cut bread, or other non-Charif Pareve food which will be used for dairy, using a meat knife, it suffices for one to clean the knife well, and Neitza is not required. Furthermore, this applies even according to the above custom to designate separate knives for meat and milk, nevertheless, one may even initially[185] use a clean meat knife to cut bread [or other non-Charif Pareve foods] which he plans to eat with cheese.[186] Practically, the custom of the world is not to cut Pareve foods that will be eaten with dairy with a meat knife even if Neitza was performed, however in a time of need one be lenient to do so if the knife is clean [even if Neitza was not performed due to inability to do so[187]].[188]

 

D. The law Bedieved if a meat knife was used to cut cheese or vice versa:

All the laws below are in reference to whether one may Lechatchila use a meat knife for dairy or vice versa. However, Bedieved that the knife was already used, all the classical rules of Issur Viheter apply and hence even in the worst-case scenario, so long as the meat and cheese were cold and a non-Charif Pareve was cut, the food remains permitted. If the knife was washed and cleaned prior to cutting the cheese, then the cheese may be [washed[189] and] eaten the way it is even if Neitza was not performed to the knife.[190] If, however, the knife was dirty from meat then one is to remove a peel[191] worth from the cheese.[192] Regarding the law of the Pareve food, and if it may be used for the opposite food-See Chapter 5 Halacha 2-3!

The law of the knife:[193] If a meat knife was accidently used to cut cold hard cheese [or cold dry meat], it suffices to perform Neitza to the knife and then return it to its designated use. [Furthermore, some Poskim[194] rule it suffices to simply wash the knife well and even Neitza is not required.] If it was used to cut regular cold meat [which is soft, or soft cheese], then a mere rinse suffices.[195]   

Q&A Are there any alternatives to Neitza?[196] Some[197] suggest that a very thorough cleansing of soap and water is equivalent to Neitza that was performed in previous times. Others suggest that as an alternative to Neitza one can clean the knife well and then pour on it hot water from a Keli Rishon.

Knife sharpener

May the same knife sharpener be used for dairy, meat, and Pareve knives? Some write that it is proper not to use the same knife sharpener for meat and dairy knives.[198] Nevertheless, from the letter of the law, it is permitted to be done.[199] Prior to sharpening the knife, one is to clean the blade well and wash down the sharpener.[200]

Knife sharpening stores: When bringing a Kosher knife to a knife sharpening store, one is to make sure that the knife is not immersed into a hot water bucket, as is done in some facilities. Likewise, one is to make a sign on the knife to make sure upon pickup that it is indeed the same knife that he gave in.  

Blenders, food processors and other appliances that contain blades:[201]

Initial custom-Two sets for meat and dairy: Blenders, food processors, and all other appliances that contain blades retain the same status and law as a knife, of which the custom is to designate one for dairy and the other for meat, and avoid cutting Pareve with one type if one intends on eating the food with the other type. Thus, initially, one is to have separate blenders for meat, dairy, and even Pareve foods, or at the very least have separate blades and bowls for processing meat, dairy, and Pareve.[202] [However, the machine which houses the motor in essence always remains Pareve, and hence can be interchanged.[203]] Practically, upon purchasing an appliance with many blades, one can designate which blades will be used for meat and which for dairy, or purchase replacement blades to designate for the other use. One should also purchase a replacement bowl, so he has one designated for meat use and the second designated for dairy use. Pareve foods that one plans to eat with dairy are to be blended with the dairy blades and bowl, and Pareve foods that one plans to eat with meat are to be blended with the meat blades and bowl. If one did not do so-see next! Due to all the above, many are accustomed to simply designate their blender as Pareve and avoid blending any dairy or meat inside.

Using the same bowl with different blades: If one does not have two processing bowls available, one for meat and one for dairy, but does have two sets of blades, then one can use the same bowl for blending both meat and dairy products, each with their respective blade, if the following conditions are fulfilled: 1) One must make sure that the processing bowl has been cleaned with soap and water and does not contain any residue of food. 2) One makes sure to use the bowl for only cold [below Yad Soledes] meat/milk foods and makes sure to wash it with only cold [less than Yad Soledes] water. 3) The bowl is not to have meat or milk soak in it for 24 hours. 4) The bowl is not to be left in a meat or dairy sink together with other dishes for 24 hours.[204] If the bowl is made of glass material, only the first condition is necessary, and it may be used for even hot foods of meat/milk, as explained in the section regarding “Glass.” In a time of need, one may be lenient by all material bowls [even if used with hot meat/dairy] so long as it is clean and the food being blended is not Yad Soledes.[205]

Using the same blades for meat and milk: It is forbidden to use the same blades for both meat and dairy products, even if they have been cleaned.[206] Bedieved, if one used the same blade for meat and dairy, the foods remain Kosher.[207]

Pareve-Using meat/dairy blades for Pareve which one plans on eating with the opposite food: As stated above, it is initially forbidden to use the blades of a meat blender for blending Pareve that will be eaten with dairy. However, in the event that one does not have another blender or blade available, then in a time of need, it may be used to blend cold non-Charif Pareve foods that will be eaten with meat/milk, if the blade and machine is thoroughly cleaned [i.e. cleaned with soap and have boiling water poured over it]. The above applies whether the blender was previously used for hot or cold meat. The above applies only to using it for cold non-Charif foods, however hot foods or Charif foods may not be used in the blender if one plans to eat them with the opposite food of dairy or meat. Bedieved, if the blender was used with hot foods or Charif foods-See Chapter 5 Halachas 2-3 regarding a knife! 

Blended Charif that was cut with meat or dairy knife: If a Pareve grater or food processor blade was used to grate a Charif food [i.e. onions] that was cut with a meat/dairy knife, it is disputed if the blades remain Pareve. If the blades were meaty and one used it to blend a Charif food that was cut with a dairy knife, it is debated if the blades must be Koshered. See Chapter 5 Halacha 6 in Q&A!

Fish/meat: If a blender was used for fish products, it must be thoroughly cleaned prior to using it for meat products. The same applies vice versa. If cleaned, it is permitted to blend the meat or fish even together with Charif foods. See Chapter 5 Halacha 3 in Q&A!

 

Microwaves:^[208]

Some Rabbanim^[209] say that one may use the same microwave for both meat and dairy, one after the other, so long as it is cleaned in-between. The majority consensus of Poskim^[210], however, is that a microwave cannot be used for both meat/dairy even one after the other.^[211] This applies even if the microwave is cleaned, and has not been used for 24 hours[212], unless the food is hermetically sealed and the microwave is Koshered, as explained below. Practically, one must abide by the latter opinion, as the former opinion does not take all factors into account.^[213] Thus, microwaves are to be designated as either meaty, dairy, or Pareve, and not be used for the opposite foods unless on occasion, as per the guidelines to be explained. According to all, a combination microwave oven, which is both an oven and a microwave, may not be alternated between meat and dairy use, and follows the same laws to be explained regarding an oven.

Cooking in a hermetically sealed container:^[214] In all cases, it is permitted to cook in a microwave food [meat/dairy] that is contained within a hermetically sealed container which does not allow any vapor to escape or enter. This applies even if the microwave has not been Koshered, and certainly if it has been Koshered in the method mentioned below.^[215] Some Poskim^[216] however discourage using the microwave in this method as it occurs that the hermetic sealing tears or opens during the cooking, which would then pose a Kashrus issue. It is therefore best to only use the microwave in this method after first Koshering it.

How to Kosher it:^[217] Some Poskim^[218] rule that it is not possible to Kosher a microwave.^[219] Other Poskim^[220] rule it can be Koshered through steaming water inside it.^[221] This is accomplished through the following steps: The microwave is to be cleaned, not used for 24 hours^[222], and have water with bleach/soap placed in it and heated for about 10-20 minutes^[223], until it steams out.^[224] Practically, one is to do as stated above, and use a hermetically sealed container to cook the food after Kashering it.

Bedieved, if used meat microwave for uncovered dairy: If one heated a dairy food in a meat microwave, or vice versa, and the food was uncovered, then if the microwave has been used for meat within the past 24 hours, or if it was dirty with meat residue, the food is forbidden. If the microwave was clean and was not used for 24 hours with uncovered meat, then the food remains permitted, although the microwave must be Koshered through the method explained above. See the section regarding “Ovens” for the sources and full details of this matter!

Mixer [cake mixer; egg beater]:[225]

Cake mixers and egg beaters may be alternated between dairy and meat use, so long as they are used for only cold foods, do not remain in the food for 24 hours, and are spotlessly cleaned between the uses.

Ovens:[226]

*The following is a summary of the detailed laws explained below. See there for all sources and background!

It is forbidden to cook meat and milk simultaneously in the same oven, or even one after the other, unless certain conditions are fulfilled which prevent the transfer of taste of meat to milk and vice versa. Accordingly, it is customary to have two ovens, one designated for meat products and the second for dairy products, and avoid the potential issues involved in alternating uses with the same oven. Many designate their main oven for meat products, while for dairy products they purchase a smaller and more portable dairy oven. Nonetheless, in the event that one desires to bake a dairy food in a meat oven or vice versa, it may be done if the conditions to be mentioned are fulfilled.

Double ovens:[227] A double oven, which contains two separate baking compartments may have one compartment designated for dairy and the second for meat if one has verified that the oven compartments are completely independent of each other and do not share the same walls, roofs, backs or vents. Practically, such an oven should be purchased with a Rabbinical supervision to verify the proper separations between the two compartments, so they can be designated for opposite uses. In the event that the proper separations have been verified, one may bake meat and milk in the two compartments simultaneously even if they become hot from each other.

Baking dairy in a meat oven or vice versa:^[228] It is permitted to bake dairy products in a meat oven in each of the following two cases:

1. Cleaning and Koshering:[229] If the oven is cleaned and Koshered beforehand, then one may bake dairy in the meat oven.[230] The cleaning can be accomplished by washing and scrubbing it clean and then turning on the oven to a hot temperature, having it burn out any leftover residue.[231] The Koshering can be accomplished through turning on the self clean cycle[232] [if available], or waiting 24 hours [from the cleaning[233]] and turning on the oven for a period of at least a half hour to its highest temperature. Some Poskim[234] write that one is to also place a pot of water inside and have its steam Kosher the oven. If the above is done, the dairy food may be baked in the oven even uncovered. However, in such a case, one must make sure to re-Kosher it prior to returning to use it for meat products. This Koshering option is even initially valid.[235] Those who plan to use this option upon purchasing an oven, should initially purchase an oven with a Teflon coating rather than enamel or porcelain.[236] The above option of cleaning and Koshering is only valid for a classic baking oven, however a small toaster oven with interior coils is very difficult to clean and is not Kasherable, and hence cannot be used for both dairy and meat foods.[237]

Or

2. Covering:[238] In a time of need[239], if one does not desire to wait 24 hours and Kosher the oven beforehand, it is permitted to cook dairy in meat oven if the dairy food is hermetically sealed in a way that it will not release any vapor [i.e. wrapped in tinfoil]. If one wraps the entire food in two coverings, such as in two sheets of tinfoil [or one wraps the entire pot in two sheets of tinfoil], then it suffices to bake it in the oven even if the oven was not cleaned of meat residue.[240] If, however the food or pot was only wrapped one time, then the oven must be cleaned beforehand from any meat residue.^[241] This can be accomplished by turning the oven on to a hot temperature and having it burn out any leftover residue.[242] It does not suffice to merely clean the oven with a sponge and water without also turning it on and burning any leftover residue that is inside.[243] The above option of a double wrapping is valid even for a small toaster oven able, and hence it can be used for both dairy and meat foods if they are hermitically covered with two coverings.[244]

Status of Pareve baked in a meat oven: See Chapter 4 Halacha 6-7!

Charif [i.e. onions] that was cut with a dairy knife in a meat oven: Initially, one may not bake Charif foods that were cut with a dairy knife in a meat oven. If one already did so, then seemingly this follows the same law as one who cooked the Charif in a meat pot, and hence the food is forbidden. The oven is to be Koshered as explained above.

The law Bedieved if the above conditions were not fulfilled: If uncovered dairy food was baked in a meat oven that was not cleaned from meat residue beforehand, then the food in the pot requires 60x versus this residue, otherwise everything is forbidden. If the oven was cleaned but was not Koshered, and the food was uncovered, then if the oven has not been used for 24 hours for meat, the food is permitted, although the oven needs to be Koshered.[245] If the oven was used within the past 24 hours for meat, then even the food is forbidden. If the food was covered in a way that vapor is not released, then everything remains permitted.

If meat and dairy were baked simultaneously in the same oven: If meat and milk were cooked simultaneously in the same oven, everything is forbidden unless both foods were properly covered to the point that they will not release vapor.

 

Background and detailed ruling:[246]

The subject of baking Kosher foods in a non-Kosher oven, or baking dairy in a meat oven or vice versa, is contains many different aspects of worry. These include: 1) Mamashus, which is having the Kosher food contact the non-kosher food that is in the oven and hence receive forbidden taste. 2) Reicha, or the smell of an Issur penetrating the Heter. 3) Zeiah, which is the vapor of an issur penetrating a Heter.[247] The Rama, based on the Rosh, innovates, and emphasizes the Kashrus concern found in the vapor of a food and how vapor is treated as actual food itself. The typical medieval ovens that existed in the times of the Shulchan Aruch did not contain a concern of Zeiah, as they were very large in size[248], and/or contained a large hole [the size of a pot] which allowed the vapor to escape. However, our ovens today which are a small closed off box, contain a serious Kashrus concern of Zeiah upon the vapor of the food hitting the ceiling of the oven.[249] Below, we will first delineate the laws written in Shulchan Aruch regarding the medieval ovens and then brings the corresponding ruling regarding our modern-day ovens.

 

Medieval ovens Versus Modern oven

The original law by medieval ovens-Baking meat and milk simultaneously in the same oven:[250]

Lechatchilah:[251] One is initially to avoid baking milk and meat simultaneously in the same oven in all cases, [even if they are covered and no steam is being released or the steam will not be Yad Soledes by the time it hits the other pot]. Thus, the following discussion is only with regards to Bedieved.

Bedieved-Medieval ovens-Bottom pot covered:[252] If dairy and meat foods were baked simultaneously in the same oven [of medieval times], with one of the foods, such as the milk, on the bottom rack and the other, such as the meat, on the top rack, then if the bottom milk pot is covered, everything remains permitted.[253] [This applies even if the dairy and meat pot were sitting one on top of the other and were both very hot, so long as the area of contact remains dry.[254] If, however, the dairy bottom pot was uncovered while the top pot was covered, everything is forbidden, as explained next.[255]]

Bedieved-Medieval ovens-Bottom pot not covered:[256] If the bottom milk pot of food was not covered[257], then the meat food which is sitting on the top rack requires 60x versus the dairy food[258], otherwise it is forbidden.[259] [However, even in the event that it contains 60x, the meat pot remains forbidden.[260] Furthermore, even the dairy food and pot become forbidden.[261] Other Poskim[262], however, rule that the dairy food and pot remain Kosher.[263] If the oven is so enflamed that the vapor becomes immediately burnt by the fire upon touching the meat pot, then everything, even the meat pot, remains permitted.[264]]

Bedieved-Medieval ovens-Bottom pot not covered-Steam is cold:[265] If the steam of milk is no longer Yad Soledes by the time it contacts the bottom of the meat pot which is sitting on the upper rack, such as when the two pots are sufficely distanced from each other, then everything remains Kosher. [This, however, only applies if the meat pot is cold. If, however, the upper meat pot is Yad Soledes, then the milk steam prohibits the meat food and pot even if the steam itself is no longer Yad Soledes by the time it reaches it.[266]]

Bedieved-Medieval ovens-Cooking meat and dairy simultaneously side by side:[267] If one cooked meat and dairy foods, or Issur and Heter, next to each other in the same medieval oven, then [if the pots were dry[268]] they are both permitted even if they were both uncovered, and released steam, and even if the pots were touching each other.[269]

Bedieved-Medieval ovens-Baked simultaneously under the same roofing:[270] If one baked an Issur and Heter simultaneously in the same oven and the oven has a ceiling on top [as opposed to being open on its top, as was common in ovens of the old days] then if both foods were uncovered everything is forbidden.^[271] If both foods are covered everything remains permitted.

The corresponding law by Modern day ovens-Baking meat and milk simultaneously: Being that our ovens are a small box shape and are sealed closed without room for vapor to escape, they are similar to the case mentioned above of dairy food being cooked under a meat surface, or meat and dairy food being cooked under the same roofing. Accordingly, modern ovens today contain a Zeiah prohibition even if the two foods are side by side, and not under one another. Thus, it is absolutely forbidden to cook meat and milk simultaneously in the same oven, unless both foods are properly covered to the point that they will not release vapor.[272] Likewise, the oven must be cleaned beforehand from any leftover meat or dairy or Issur substance [unless the food is doubly wrapped[273]].[274]

           

The original law by medieval ovens-Baking one after the other:

Medieval oven-Baking in a pot on the floor of the oven:[275]  If meat was cooked in a pot within a [medieval] dairy oven, or vice versa, then although the meat pot is resting on a dairy surface, nevertheless, if the oven surface is clean from any residue of dairy [and both the pot and surface are dry[276]], everything remains Kosher. This applies even if the surface had a dairy food directly baked on it within 24 hours, and it had thus absorbed milk.[277] [Nonetheless, this only applies if one verified beforehand that the surface of the oven was clean of residue.[278] Practically, it is proper to initially avoid baking meat in a dairy oven, even if the surface area is clean, if the matter is not necessary.[279]]

Medieval oven-Baking directly on the floor of the oven?[280] It is forbidden to rest and bake dairy products directly on the surface of a meat oven [without a pot, tinfoil, etc] if gravy of meat at times spills on the surface of the oven, unless the oven is Koshered through performing Libun Gamur.

Medieval oven-Baked one after the other under the same roofing: If one did not bake the Issur and Heter simultaneously, but rather first baked the Issur and then baked the Heter, the Heter remains permitted even if it was baked uncovered under the same metal roofing of the oven, so long as the roofing did not receive condensation from both foods.^[281] [This allowance applies even if the oven is still Ben Yomo from the Issur and even if the Issur is a food made to give smell and the smell still remains in the oven.^[282]] If, however, the Issur and Heter both^[283] gave off vapor to the metal roofing, thus causing condensation [and now the Heter vapor mixed with the leftover Issur vapor], then everything is forbidden even if they were baked one after the other, just like is the ruling regarding placing a meat cover over a milk pot.^[284] [However, if the oven is no longer Ben Yomo then the food is permitted.^[285]]

The corresponding law by Modern day ovens-Baking dairy in meat oven:[286] As explained in the introduction, modern ovens today contain a Zeiah prohibition, and is thus similar to the case where dairy is baked under a roofing that had meat baked under it, and both the meat and dairy release vapor. Accordingly, the roof and walls of an oven are saturated with taste of the foods cooked in it and receive a meat/milk status similar to that of a meat/dairy. Thus, it is forbidden to cook uncovered meat in a dairy oven or vice versa, or cook uncovered Heter in an Issur oven, unless the oven was Koshered beforehand. If, however, the meat/dairy/Heter which is now being cooked in the oven is covered to the point that it will not release vapor, then [in a time of need[287]] it is permitted to be cooked in a dairy/meat/Issur oven, so long as it is clean from any leftover meat/dairy/Issur substance and the pot and surface area are dry.[288] See Chapter 8 Halacha 32 for additional Q&A on this subject!

Napkins:[289]

It is permitted to use the same cloth napkins for both meat and dairy if the napkins are laundered between uses.[290] Nonetheless, those who are scrupulous designate separate meat and dairy napkins for the meals. It is permitted to wash both meat and dairy napkins together in the machine.[291]

Peeler:[292]

It is best for peelers that are used to peel fruits and vegetables to be designated as Pareve and be kept as such. Thus, one is to avoid using the peeler to peel hot meat or dairy foods, or to peel Charif foods that have been cut with a meat or dairy knife [i.e. horseradish cut with meat knife], and one is to avoid washing them with meat or milk dishes. Those who have separate peelers for meat, milk, and Pareve are to mark them in a way that their designation is openly visible. The need for a Pareve peeler is especially applicable when peeling Charif foods, in order so they can be used for whatever one desires.

Time of need: In a time of need one may use a meat peeler to peel fruits and vegetables that will be eaten with dairy so long as the peeler is clean and the food being peeled is not Charif.

Bedieved: If a meat or dairy peeler was used to peel a Charif food, the Charif should not be eaten with the opposite food.[293] Bedieved, if the Charif was already used for the opposite food, the food remains permitted.[294]

Pitchers:[295]

It is permitted to use the same drink pitchers for both meat and dairy meals, so long as one guards it as Pareve. The same applies towards water bottles [that one does not drink directly from the cap]. If the pitcher is used for dairy drinks [i.e. milk] then it is to be designated as dairy and not be used for meat meals. However, in a time of need, one may use a dairy pitcher for a meat meal so long as the pitcher is cleaned beforehand. This especially applies towards glass pitchers.[296]

Pitcher used for hot drinks: If the pitcher is used to serve hot dairy drinks [coffee], it should be designated for only dairy use. However, glass pitchers may be used for hot drinks for both meat and dairy meals so long as it is properly cleaned in between.[297] In a time of need, pitchers of any material may be used for an opposite meal so long as the pitcher is clean and is used for cold drinks.

Scissors [Kitchen & Food]:[298]

Kitchen scissors follow the same rule as knives and hence are not to be used for cutting both meat and milk. Thus, one is to designate one pair of scissors for dairy use [i.e. opening milk bag], and a second for cutting meat and chicken.

Sponges:

Initially, one is to designate separate sponges for washing meat, dairy and Pareve dishes, and so is customary of all Jewry today.[299]

Bedieved: In the event that one used a meat sponge to wash a dairy or Pareve vessel or vice versa, everything remains permitted and retains its status. This applies even if the sponge was dirty with meat or dairy residue, and the vessel was dirty with meat/milk, so long as hot Yad Soledes water was not used. In such a case, one is to immediately wash the sink and any vessels that are in it with cold [or less than Yad Soledes] water.[300] If one used Yad Soledes water, then the vessel is forbidden, unless the sponge contained soap from the very onset of the use of hot water.[301]

Time of need: In a time of need, one may use a meat/dairy sponge to wash the opposite plate on condition that a) one washes the sponge clean of any residue and b) one uses only cold water.

Sinks:[302]

*See Chapter 8 Halacha 30D for the Halachic background on this subject!

It is proper to have two separate sinks, one for meat and one for dairy, and so is the widespread custom of Jewry today. Doing so escapes the Halachic questions that can arise when using the same sink.[303] It is proper that each sink contain its own faucet, its own drainage system, and be some distance from each other. Nevertheless, from the letter of the law, it is permitted to use the same sink for washing meat and milk dishes, if certain conditions are fulfilled.[304]

Using the same sink for meat and milk dishes:[305] If one only has a single sink available in his kitchen, then it is best to designate the sink for the most common use in one’s home, whether meat or dairy, and purchase a sink insert to use when washing the opposite dishes. One is to avoid pouring hot Yad Soledes water, or turning on Yad Soledes faucet water, while washing the dishes in the sink insert, if the water drains directly into the meat sink.[306] After using the sink insert, one is to clean the sink from any dairy residue that may have escaped into it. If one does not own a sink insert, he may use the same sink for washing meat and dairy dishes if the following conditions are fulfilled:

1. One cleans the sink from residue prior to placing the meat or dairy dishes into it.[307] [It is difficult to determine whether a sink is cleaned of fat and oil residue through a taking a mere glance, and hence one is to wipe the sink with a sponge and then feel with his hands to verify that in truth no residue has remained.]
2. One does not pour hot food [especially hot meat, or dairy] into the sink unless the sink is clear of any dishes.[308]
3. When washing the dishes, one is to use less than Yad Soledes water.[309]
4. One does not allow a vessel to remain in the sink for 24 hours.[310]

Sponges: Initially, one is to designate separate sponges for washing meat, dairy and Pareve dishes, and so is customary of all Jewry today. See the section on “Sponges.”

Sink backup with same drainage system:[311] If one’s meat and dairy sinks share the same drainage pipes, one is to look out for backups in the system which can cause meat and dairy residue to enter each other’s sinks. In the case of a backup, one is to make sure that all the vessels in the sink are removed within 24 hours and cleaned well with cold water. Likewise, the sink must be cleaned of the mixed residue within 24 hours.

What is the law if one found a milk dish in his meat sink or vice versa? See Chapter 8 Halacha 31!

Koshering a sink: The Koshering of a sink is dependent on its material. A metal sink can be Koshered through Iruiy Keli Rishon. Most sinks, however, are made of porcelain or enamel which are non-Kosherable materials.

 

Sinks that contain a shared wall, or are attached to each other?[312]

The recommended practice: It is initially proper not to have a shared sink, and that each sink should have its own four individual walls, and not be attached in any way. This especially applies to a metal sink.[313] Having completely separate and detached sinks avoid any possible Kashrus concerns.[314] Nonetheless, the following is the letter of the law regarding this matter and can be chosen to be kept by the individual, if he so desires:

The letter of the law-shared walls [see Exhibit A]: A meat and dairy sink should not share walls with each other if the wall is very thin.[315] This applies irrelevant of the material of the wall. If the wall is metal, then it should not be shared even if the wall is very thick, although those who are lenient have upon whom to rely.[316] If the wall is thick and is made of non-metal material, it may share walls with the other sink, although there is room to be stringent even in such a case.[317]

The letter of the law-attached on top [see Exhibit B]: A meat and dairy sink may be made of a single unit and be attached to each other at their top.[318] This applies with any material sink, even metal, although there is room to be stringent by metal sinks.[319]

                                             

Salt shakers, spices and dips:[320]

Salt plates:[321] One who has a salt plate which is placed on the table during meals, is to designate separate salt dishes for dairy and meat, as the salt dish may contain residue of the food dipped in it.

Salt shakers:[322] From the letter of the law, salt shakers may be used for both meat and dairy foods so long as they remain clean from any contact with meat or milk, and do not absorb their vapor. However, it is a Mitzvah Min Hamuvchar, and so is the custom, to designate one for meat and one for milk.[323] The two salt shakers should be marked in a way that their meat or dairy status is visible to all.

Spices/ketchup: Based on the above, it is proper to have separate spices and ketchup for meat and dairy use. Nonetheless, from the letter of the law one may use them for both meat and dairy foods so long as one is careful that they do not come into contact with the food, or absorb from their vapor.

Steam cooker-Industrial:[324]

Many industrial kitchens and food plants contain steam cooking pots which receive their heat through a steam boiler. The boiler produces steam which is then released through connective piping to the various cooking pots connected to its system. This allows for the quick and high pressure cooking available through steam, and is a necessity for all industrial plants and kitchens. This, however, poses the following Kashrus concerns: Being that all the pots receive the steam directly from the same boiler system, it is imperative that the entire system and its pots be designated for only one use; either meat or milk. It does not suffice to have different pots designated for meat and milk and then connect them even at separate times to the steam boiler.[325]

Stoves [Gas]:[326]

It is highly recommended to have two separate stoves for meat and dairy in order to avoid possible Kashrus complications that can arise when sharing the same stove for cooking both meat and milk.[327] If one is unable to purchase a separate stove top, he is at the very least to purchase separate grates for meat and milk which are to be alternated for the cooking of meat and dairy products.[328] Alternatively, rather than buying two sets of grates, some of the grates should be designated for meat use while the others for dairy use. Alternatively, one can use the grates for one food and place a metal grate cover over the grates when cooking the opposite food. The above is all in accordance to the initial and recommended practice, however, from the letter of the law, it is permitted to use the same grates for cooking both meat and milk, so long as certain guidelines are followed:^[329]

The necessary precautions when using the same grates for meat and milk:[330] If one desires to use the same grates for both meat and milk, one must beware of the following matters:

1. Clean: One must verify prior to each use that there is no residue of food left on the grates [or bottom of the pot].^[331] [Thus, the grate should be cleaned with soap and water. A mere glance does not suffice to detect oil and fat residues. One is not to suffice with simply turning on the flame to burn any residue, as often the flame does not reach all areas of the grates.[332]]
2. Dry: One must verify that both the grates, and the pots being placed on the grates, are completely dry.^[333] [The pot bottom should be dried with a towel if wet, while the grates can be placed on the stove top and dried through turning on the flame, prior to resting the pot on it. It is advisable to leave a towel in close distance from the stove top to use for the drying.]
3. Spillage: The pot is not filled and heated in a way that will cause spillage onto the grates upon it reaching a boil. If in the event of the cooking the food boiled over and spilled towards the grates, hence making them wet, then this follows the same laws as one who cooked with a wet pot or grate, as brought below!
4. One may never place any foods [as opposed to pots] directly on the grates, as the grates themselves are considered Treif and can transfer forbidden taste to the food even without liquid.[334] One may, however, place the food on tinfoil and then rest it on the grate.

Bedieved if one cooked dairy on a meat stove top grate which was dirty or wet or vice versa?[335] If one cooked a dairy pot of food on grates that were visibly dirty from meat, the pot and its content are forbidden unless the food contains 60x versus the meat residue, in which case the food is permitted while the pot must be Koshered.[336] If the grates were clean but wet, or the bottom of the pot was wet, or the pot boiled over onto the grates, then if the grates had not had meat cooked on them in the past 24 hours, the dairy food and pot remains permitted. Furthermore, even if a pot of meat was cooked on the grate within the past 24 hours, the food is permitted if one does not know for certain that meat food spilled on it within the past 24 hours.[337] If, however, one knows for certain that meat spilled on it within the past 24 hours, then even if it is now clean, some Poskim[338] rule the food is forbidden.

Cooking meat and milk on different grates at the same time:[339] Initially, one is to avoid cooking meat and dairy foods next to each other on the same stove top at the same time.[340] Nonetheless, if one did so, everything remains permitted so long as no spillage was witnessed. This applies even if both pots were uncovered and released steam, and applies even if the pots were touching each other [if the pots were dry[341]].[342] When cooking in such a way, extra care must be taken when mixing the food and lifting up the covers, to avoid spillage onto the opposite pot.

The status of the grates and stove top area if used to cook meat and milk: In all cases that the same stove top is used for cooking meat and milk, [irrelevant of whether the same grates are used] the stove top area under the grates is considered not Kosher due to spillage of hot meat and milk. Therefore, one may not place any food there. If food falls onto the stove top while hot, the food is forbidden[343] unless the stove top is clean and has not received spillage within the past 24 hours.[344] Whenever the same grates are used for both meat and milk, per the guidelines set about above, the grates are considered Treif and any hot food that falls on them is forbidden unless the grate is clean and not Ben Yomo of spillage, as stated above regarding the stove top.

Koshering grates: When Koshering grates that became forbidden due to absorbing taste of Kosher meat and then Kosher milk one is only required to perform Hagala to the grates and not Libun Chamor.^[345]  If, however, it absorbed the taste of forbidden mixture of meat and milk, then Libun Chamur is required.[346] [For example, if milk spilled on the grate, was cleaned off, and then meat spilled on the grate, the grate requires Hagala. If, however, the grate was not cleaned off, and a piece of meat fell onto the milk that is on the grate, and the hot grate absorbed from that meat-milk mixture, then it requires Libun Chamor.]

Range/exhaust hood:[347] If one would like to install a range hood above his stove to absorb vapor, then if one plans to use the stove for cooking both meat and dairy products, it is to be installed high enough so by the time any vapor touches it, the vapor is no longer Yad Soledes. If the range hood has already been installed and is not this distance away, then one may not cook both meat and dairy products under it unless the machine is on and working.

Cabinets above stove/oven:[348] It is best to avoid having cabinets above the stove or oven in which food or vessels are stored, as the vapor of the foods that are cooking could potentially contact those foods and vessels. [However, in a time of need, so long as the vapor does not directly hit the food or vessels, it is permitted to be done. In such a case, one is to make sure to keep the cabinets closed during cooking, and to rinse off the pots prior to use.[349]]

Stove [Electric]:

There exist several forms of electric stove tops to which their Halachic status varies. The common denominator between them all, is that they can pose potential Kashrus issues if certain guidelines are not fulfilled, and hence it is recommended to simply designate different burners for meat and milk.[350] Nonetheless, from the letter of the law, one may alternate usages between meat and milk, so long as the corresponding guidelines are followed, as explained next:

Elevated electric coils: An electric stove top which contains elevated coils, and hence has the entire pot of food rest only on the coils [and not the surface of the stove top], may be alternated in use between meat and dairy so long as one turns on the heating element and has it become red hot prior to placing the pot onto it.[351] However, one must verify in such a case that any food residue that fell under the coil is also burnt to ash, as otherwise its steam can prohibit the pot that is resting on the coil. If the food that rests under the coils is not burnt to ash, then one must remove the coils, and clean the area prior to cooking foods on those coils.

Electric Ceramic cook top: An electric ceramic stove top contains surface areas that are not Kosherable through simply turning on the stove.[352] Thus, when using such a stove for cooking both meat and dairy products, the following guidelines must be followed:^[353]

1. Clean: One must verify prior to each use that there is no residue of food left on the stove surface [or bottom of the pot].^[354] [Thus, the surface should be cleaned with soap and water. A mere glance does not suffice to detect oil and fat residues.]
2. Dry: One must verify that both the surface and the pots being placed on the surface are completely dry.^[355] [The pot bottom should be dried with a towel if wet, while the stove surface can be dried through turning it on prior to resting the pot on it.] If the above conditions were not followed-See above regarding gas stove tops!

Electric Glass cooktops: Many Poskim[356] rule that glass material is nonabsorbent and hence one may use a verified pure glass cooktop for cooking both meat and dairy foods so long as the glass is properly cleaned beforehand from any residue. [The surface must be cleaned with soap and water as a mere glance does not suffice to detect oil and fat residues.] There is no need to Kosher it beforehand or make sure the surface area is dry. Practically, Sephardim may be lenient in this matter and even Ashkenazim who are lenient have upon whom to rely.[357] Nonetheless, it is initially proper to abide by the second condition explained above and verify dryness of the surface and pot prior to use.

Induction cooktops: Induction cooktops which heat food through magnetic induction are unable to be Koshered through simply turning them on. They therefore follow the same laws as a ceramic or glass electric cooktop, as explained above. If made of ceramic material, then cleanliness and dryness must be verified before each use if one desires to alternate between cooking meat and milk. If it is made of glass, then it follows the similar glass leniencies explained above.

Tablecloths:[358]

It is forbidden to eat meat on a tablecloth that was used to eat cheese.[359] The same applies vice versa.[360] [This applies even if one cleans the tablecloth well.[361] Likewise, one may not eat both meat and dairy meals on a table that does not have a table cloth. If one desires to eat directly on the table, it should be designated for one use, while the second use is eaten on a tablecloth or tray. In the IDF, tablecloths are not used, and in exchange the meat and dairy meals are all served on personal trays. Nonetheless, some Poskim[362] record that it is always proper to have a tablecloth on the table, and not eat directly from it.]

A long tablecloth:[363] If one has a long tablecloth, he may designate one side to be used for meat and the other side for milk.

If one only eats on plates:[364] Today the custom is to eat on plates and not directly on the tablecloth. Accordingly, from the letter of the law, one is not required to have separate tablecloths for both milk and meat. Nonetheless, the custom is to be stringent. It suffices, however, to simply designate one side of the tablecloth for milk and the other side for meat.

May one use one side of the tablecloth for dairy and the other side for meat?[365] If the tablecloth is made of a durable material which prevents leakage to the other side, one may use one side for meat and the other for dairy.

One used the tablecloth for meat and milk? If a dairy tablecloth was used for meat, or vice versa, it suffices to wash it clean. If hot meat spilled on it, it can be Koshered through washing it with hot water and laundry detergent.[366]

Laundering a tablecloth: A tablecloth made of machine washable material [i.e. cloth versus plastic], may be placed in the wash and afterwards be designated for the opposite use, as explained above regarding Koshering. It is permitted to wash both meat and dairy tablecloths together in the machine.[367]

Thermos:[368]

A thermos which is used for storing hot water or tea retains a Pareve status. If it is used for coffee with milk, it should be treated as dairy and not used for meat meals.[369] One should avoid pouring from the thermos directly onto meat or dairy products in order for it to retain its Pareve status according to all. See the section below on “Water boilers.”

Toaster:[370]

A toaster machine, which is used for toasting only bread retains a Pareve status so long as all the bread placed inside is plain, and clean of milk or dairy products, such as butter.

Bedieved if used with dairy: If one toasted bread with butter in the toaster, the toaster loses its Pareve status and becomes dairy. It may no longer initially be used to toast bread to be eaten with meat.[371]

Trays:[372]

Food trays are to be designated as meaty or dairy, and not be alternated in use between the two.[373] In the event that a meaty tray was used for dairy, or vice versa, it is to simply be washed and cleaned and then returned to its designated use. It should be cleaned with cold water in the sink that corresponds to the currently eaten food.

Trivets:[374]

One is to have a separate set of trivets for meat and dairy foods in order to prevent possible transference of residue onto an opposite pot.  

Water boiler[375]

Initially, water boils are to be designated as Pareve in order so they can be used for both meat and dairy foods.[376]

Time of need: In a time of need, one may use a dairy water boiler for the sake of meat foods, and vice versa, so long as the water boiler has not been used with hot dairy within the past 24 hours. See Chapter 5 Halacha C-D for the full details of this ruling!

Pouring directly onto meat/milk: In order for a water boiler to remain Pareve, one is to avoid pouring it onto meat or dairy unless both the water and the meat/dairy foods are cold. Thus, one is to avoid pouring hot water from a Pareve urn onto a cup that contains milk. One is to rather pour the water into an empty meat/dairy vessel and only then place the meat/dairy into it. This especially applies, and is required, if the water is cold while the meat/milk is hot. However, if both the water and meat/dairy are hot, or the water is hot and the meat/dairy is cold, then one may choose to be lenient so long as it is done from a far enough distance that hot steam from the meat/milk will not contact the Pareve. Bedieved, if one poured from cold water to hot meat/dairy, the remaining water and the water boiler remain Pareve so long as hot steam of the meat/milk did not hit the Pareve, although some are stringent in such a case that it is no longer considered Pareve. See Chapter 8 Halacha 28 for the full details of this subject!

Placing meat or dairy products on it to heat up: A water boiler which had meat or dairy products placed on its cover for the sake of heating up, becomes meaty/dairy unless the meat/dairy was heated on an intervening substance, such as tinfoil, and there was no moisture in-between the tinfoil and cover. In the event that it was placed directly onto the cover, or there was moisture between the cover and tinfoil, then even the water becomes dairy/meaty and is forbidden to be eaten with the opposite food. It goes without saying that one may not heat both meat and dairy products on the same water boiler cover, unless they are covered in tinfoil.

Spillage: If milk or meat gravy splashed onto a Pareve water boiler, the boiler now becomes meaty/dairy unless it is Koshered. See Chapter 8 Halacha 14!

_____________________________________

[1] An example of this philosophy can be found in the IDF Rabbinate Kashrus regulations, which prohibits the cooking or heating of dairy products in the army kitchen. [As an IDF chaplain, I was charged with overseeing the adherence to this regulation in my base, and it was never broken even once under my duty.] Now, everyone agrees that you may cook both meat and dairy in a kitchen so long as there are separate areas and utensils for both foods, and the army is equipped with separate sections and vessels for meat and milk. Why then do they prohibit the cooking or heating of dairy? To avoid potential issues of Kashrus coming up. This army regulation was not innovated as simply a good idea, but rather as a necessity for the reality of army kitchens, as they came to learn after experimenting various Kashrus failures due to the use of hot dairy. The same then applies with all matters of accustomed stringencies and directives, that their purpose is not to establish new binding laws for the populace, but rather as good advice to help avoid the surfacing of issues, as has been seen from past experience.

[2] See Hakashrus 1:1-3

[3] See Hakashrus 2:5; 3:5; Yabia Omer Y.D. 3:4; 4:5

[4] Admur 494:16; 509:11; Michaber 509; [There they rule that one may Kosher through Libun a dairy skewer in order to use it for meat]; Magen Avraham 509:11; Shach Y.D. 95:9 in name of Tur; Shaar Hamelech Yom Tov 4:8; Hakashrus 3:5

Other Opinions: Some Poskim rule that one is to be stringent to avoid Koshering vessels even through Libun for the sake of interchanging between dairy and meat uses, just as we are stringent to avoid Hagala, as will be explained next. [P”M 451 A”A 30; Shearim Hametzuyanim Behalacha 56]

[5] Admur 494:16

[6] Admur 494:16; and 461:1; 451:7 regarding Chametz

[7] Admur 451:13 in gloss; 1^st approach in Shach 121:7; unlike 2^nd approach in Shach ibid, based on ruling of Ramaz, 96 that requires Libun Chamur even by Basar Bechalav if it absorbed meat or dairy directly without liquid

[8] Magen Avraham 509:11 [omitted from Admur ibid]; P”M 452 A”A 13; 509 A”A 11; Kitzur Shulchan Aruch 56:15; Chasam Sofer YD 110; Maharsham 2:241; M”B 451:19; 509:25; Shearim Hametzuyanim 46

Background: In chapter 509 the Michaber and Admur ibid rule that one may Kosher through Libun a dairy skewer in order to use it for meat. As well, the Shach in Yoreh Deah 95:9 brings the Tur who rules that it is permitted. The Magen Avraham [509:11], however, writes that this only applies to Libun, however, regarding Hagala, the world is accustomed to avoiding switching meat and milk vessels through Hagala. The Poskim ibid rule like the Magen Avraham.

The reason: If it were to be allowed to Kosher and switch vessels from meat to dairy and vice versa, doing so can lead to confusion as to the status of the vessels and one may come to use a dairy vessel for meat or vice versa. [M”A ibid in name of Hagaon Mipuzna]

[9] Shach Yoreh Deah 89:22 95:9; 121:16; Shut Harosh 20:25; Aruch Hashulchan 89:17; 121:11 that this is a mere stringency and we cannot make up decrees on our own; See Shearim Hametzuyanim 56

[10] Hakashrus ibid

The Sephardic custom: The Sephardic custom is not to be particular against Koshering and switching meat vessels for dairy use and vice versa. [Peri Chadash Y.D. 97:1; Machazik Bracha 509:2; See Yabia Omer Y.D. 3:4; 4:5; Hakashrus ibid]

[11] Sefer Hakashrus 3:5 [p. 83]

[12] Maharsham 2:241; Shearim Hametzuyanim 56

[13] P”M 452 A”A 13

[14] Maharsham 2:241; Darkei Teshuvah 122:49; Shearim Hametzuyanim 56 in name of Maharsham ibid and Daas Kedoshim; Hakashrus ibid

[15] See Halacha D for the significance of the passing of 12 months.

[16] Sheileiy Tziyon Tinyana Y.D. 32; Shevet Hakehasi 1:225; Hakashrus ibid footnote 17

[17] Chasam Sofer ibid; M”B 451:19; See Shraga Hameir 6:22

[18] P”M 509 A”A 11; Maharsham 2:241; M”B 509:25; Beir Moshe 3:105

[19] See Hakashrus ibid

[20] Maharsham 2:241; Daas Kedoshim; Darkeiy Teshuvah 121:59; Shearim Hametzuyanim 56; Tzitz Eliezer 9:38

[21] Beir Moshe 3:105; Rivivos Efraim 5:519; Hakashrus ibid; See Lechem Hapanim Y.D. 121 in name of Shlah

[22] Absorbed meat taste and then dairy taste: By Basar Bechalav, we never require Libun Gamur by a Kosherable vessel that absorbed meat and then absorbed milk [Admur 451:13 in gloss; 1^st approach in Shach 121:7; unlike 2^nd approach in Shach ibid, based on ruling of Ramaz 96, that requires Libun Chamur even by Basar Bechalav.]

Earthenware: Regarding earthenware [and all other non-Kosherable materials], Libun Gamur is required even by Basar Bechalav that became absorbed one after the other. [See Admur 494:16; and 461:1; 451:7 regarding Chametz]

Absorbed the prohibits taste of Basar Bechalav: If the vessel absorbed the taste of a forbidden mixture of meat and milk, then Libun Chamur is required. [See Admur 451:13]

[23] Chacham Tzevi 75, 76 and 80 [regarding Bedieved even with Charif, based on Michaber Y.D. 135 that 12 months suffice for Yayin Nesech vessel, although, Lechatchilah is Machmir], brought in Pischeiy Teshuvah Yorah Deah 122:3 and Shaareiy Teshuvah Orach Chayim 451:1; See Sefer Hakashrus p. 176

[24] Rashba 575; Chaim Sheol 2:38; Panim Meiros 1:31; Teshuvas Rav Akiva Eiger 43; See Pischeiy Teshuvah ibid; P”M 103

[25] Conclusion of Chaim Sheol 2:38 regarding a porcelain vessel bought from a gentile and one is unsure if it was used for non-Kosher that possibly one may be lenient to a Sfek Sfeika; Seemingly, all the more so would this allowance apply by meat and milk, as it is not considered Derech Bishul and hence is a mere Rabbinical prohibition.

[26] Conclusion of Pischeiy Teshuvah and Shaareiy Teshuvah ibid

[27] See Chaim Sheol 2:38 regarding one who is unsure if a new vessel bought from a gentile was previously used for non-Kosher; Admur 451:5 regarding one who is unsure of a vessels Chametz status

The reason: As it is a case of doubt to which we rule stringently. Now, although if the pot is no longer Ben Yomo it is a case of Rabbinical doubt, nevertheless, since this doubt is due to ignorance, it is not considered a doubt at all and one cannot apply the rule of Safek Derabanan Lihakel. [See Michaber Y.D. 98:3, Shach 98:9 and Taz 98:6 regarding Daas Shotim that it is not considered a Safek even by a Rabbinical case] Furthermore, one may come to use the pot with a Davar Charif and the opposite dish, which according to many Poskim makes it Biblically considered like the taste of the pot even when not Ben Yomo. [See Panim Meiros 1:64; P”M 96 M”Z 1 based on Rashba 496; Shivas Tziyon 32; Rav Akiva Eiger, brought in Pischeiy Teshuvah 95:4]

[28] See Rama 95:2

[29] Conclusion of Chaim Sheol 2:38 regarding a porcelain vessel bought from a gentile and one is unsure if it was used for non-Kosher that possibly one may be lenient to a Sfek Sfeika; Seemingly, all the more so would this allowance apply by meat and milk, as it is not considered Derech Bishul and hence is a mere Rabbinical prohibition

[30] Conclusion of Pischeiy Teshuvah and Shaareiy Teshuvah ibid

[31] See the section on “Glass vessels”, and that the main opinion follows as rule the Sephardim that is does not absorb. Hence, in a case of doubt certainly even Ashkenazim may be lenient, as writes Chaim Sheol ibid

[32] See the above Halacha regarding glass, that glass cookware is more stringent than regular glass, and hence it would be proper for Ashkenazim to Kosher it if they are unsure of its status.

[33] Rama 89:4 regarding knives; Aruch Hashulchan 89:16 and Kaf Hachaim 89:79 regarding other vessels; See Darkei Teshuvah 89:54 that one is not to swerve from this custom, and is to specifically mark the dairy vessels, as if one marks the meat vessels it can cause confusion amongst others. See there for other details of this custom; See Sefer Kur Hamivchan Teshuvah 41; Hakashrus 2 footnote 5

[34] If the Pareve utensil soaks in meat or dairy residue for 24 hours, it is no longer considered Pareve. This certainly applies if hot water is poured inside, or one washes the dishes in hot water.

[35] Hakashrus 2:63

[36] See Hakashrus 1:4-8; 2:3

[37] As there is no Halachic issue with a dry meat vessel and a dry dairy vessel being stored within each other.

[38] If the vapor hits the vessel or food while Yad Soledes, then its taste penetrates the vessel and food and can prohibit an opposite form of vessel, and turn Pareve foods into meaty or dairy. If, however, the vapor is not Yad Soledes by the time it hits the vessels or food, then everything remains its status, although the vessels are to be washed prior to use in order to wipe away any less than Yad Soeldes vapor that reached it. See our corresponding Sefer “A Semicha Aid for the Laws of Basar Bechalav” Chapter 92 Halacha 9A

[39] In the IDF, the Kashrus supervisor examines the cutlery prior to each meal to make sure there is no mix-up of vessels.

[40] See Hakashrus 1:34-37; 2:18-24

[41] Covering the pot/pan with tinfoil: It does not suffice to cover a pot or pan with tinfoil and bake or cook in it the opposite food, as if any liquid passes through the tinfoil, everything becomes forbidden. Nonetheless, if in truth one were to ascertain that the pots tinfoil lining remains hermetically sealed without allowing any moisture to pass in between, then technically the meat or dairy food cooked in its opposite type pot would remain permitted. Nevertheless, this is not to be done due to that it is very difficult to ascertain. [Avnei Yashpa 3:72; Hakashrus 1 footnote 67 in name of Rav Elyashiv]

[42] See Hakashrus 1:35

[43] Regarding the Sephardic ruling and custom-See Chapter 4 Halacha 1, although see Poskim in next footnote.

[44] See Shulchan Gavoa 1; Kaf Hachaim 95:4

[45] Implication of Michaber 95:1 and Chulin 111a “One who roasts fish in a meat pot may eat it”; Taz 95:3 “One can learn from here that there is no danger in eating fish that contains the taste of meat through being cooked in a Ben Yomo pot of meat”; Issur Viheter 39:26 “All secretion of taste of meat that is absorbed in a vessel into fish is not Bedieved forbidden due to danger”; Rashal Kol Habasar 9; Kneses Hagedola 116:18; Minchas Yaakov 57:1 concludes “The custom is to be lenient [even initially-Kaf Hachaim 116:20] if the pot is clean”; Peri Megadim 95 M.Z. 3 defends the ruling of the Taz ibid; Lechem Hapanim 116:3; Beis Lechem Yehuda 116:4; Chochmas Adam 68:1; Eidos Biyihosef 2:46; Divrei Hillel 2:32; Daltei Teshuvah 95:5; Ikareiy Hadat Y.D. 14:10; Zechor Leavraham 3:186; Darkei Teshuvah 116:27; Kaf Hachaim 116:20; Sheivet Halevi 6:111 writes it is the custom of the world to be lenient.

The reason: As the danger of eating fish with meat only applies if it contains substance of the meat, and does not apply towards the indirect taste transferred through a pot. [Taz ibid; Issur Viheter ibid]

The proof: As the Gemara Chulin ibid discusses the law of fish that was cooked in a meat pot and whether it may be eaten with dairy, thus proving that regarding Sakana there is no issue. [Issur Viheter ibid, brought in Taz ibid]

[46] Tur 116:2 “Some are stringent to designate vessels for fish” [brought in Chochmas Adam 68:1, Omitted from Michaber 116:2]; Rashal Chulin 7:15, as understood by Minchas Yaakov 57:1, that it is forbidden to eat it [brought in Derisha 116:5; Taz ibid; P”M ibid; However, see P”M ibid who vehemently negates this understanding of Rashal concluding “I wonder at this great Rav , as seemingly he did not look at the words of the Rashal”]; See Issur Viheter ibid who implies that it is only permitted Bedieved

[47] The reason: As the danger of meat and fish applies even by mere taste that is transferred through a pot. Now, although the Gemara and Michaber ibid write that it is permitted to eat fish cooked in a meat pot, that is referring to the laws of meat and milk, as in truth due to Sakana, it is forbidden. [See Rashal ibid; Taz ibid in his initial explanation]

[48] Minchas Yaakov ibid; Chut Hashani 67; Sheivet Haleivi ibid “The custom of the world is to do so”; Halacha Berurah ibid

[49] Sheivet Halevi ibid; Hakashrus 2:1

[50] See Hakashrus 1:9-12

[51] Yad Avraham 88 “Nevertheless, the Jewish people are holy and are accustomed to have separate tables for meat and milk.”; Darkei Teshuvah 88:9-11

The reason: This is done in order to prevent possible mixtures of meat and dairy from occurring. Many counters contain leftover foods either due to placing food directly on it, or having food spill. Often, it is difficult to tell that the counter is truly clean and one may come to place a meat food on dairy leftovers or vice versa. This especially poses an issue if one places hot food on the counter, in which case it will absorb the taste of the leftover meat/milk. [See P”M O.C. 173] Furthermore, even if the counter is clean, if it is used for both meat and milk it will most certainly become Treif, either due to spillage of hot meat and milk onto the counter, or due to leftover meat and milk soaking on it for 24 hours in the moisture that is commonly found on the counter. This will then require one to be very careful to never place hot food directly on the counter, including hot pots, as if one does so and the counter is wet, it can prohibit the pot and food, as explained next. [See Admur 451:58; Hakashrus ibid footnote 14]

[52] The reason: As the counter is most likely Treif due to hot spillage, as explained in the previous footnote, and if one places a hot pot or hot food directly on the counter, even if clean, it can prohibit the pot/food, as explained next. Nonetheless, if in truth the counter is clean and dry, then from the letter of the law it is permitted to place a hot dry pot [not food] onto it directly, as explained next.

[53] See Chapter 8 Halacha 16! Likewise, seemingly the counter also remains Kosher as the cheese is in the place of the Kelipa.

[54] This applies even if the counter was clean and not Ben Yomo. See Chapter 8 Halacha 20C

[55] P”M 92 M.Z. 29; Regarding Ben Yomo versus non-Ben Yomo -See Chapter 8 Halacha 2D and 20C!

The reason: As if there is moisture in-between the two materials, it serves as a conduit to transfer taste and prohibit the food.

[56] See Rama 93:1; Taz 92:29; 97:3; Admur 451:41 and 67; Kneses Hagedola 92:73; Peri Chadash 92:36; Minchas Yaakov 56:22; Lechem Hapanim 92:54; 97:1; Halacha Pesuka 97:1; Beis Lechem Yehuda 92:40; P”M 92 M.Z. 29; 97 M.Z. 1; Sheilas Yaavetz 103; Erech Hashulchan 92:15 that so is opinion of all Achronim; Chochmas Adam 50:2; Zivcheiy Tzedek 92:79; Kaf Hachaim 92:103; 97:29; See Tzemach Tzedek O.C. 43

The reason: As this is similar to two pots touching each other in which we rule that both pots are Kosher, even though both pots contain absorption of taste of the opposite food. [Taz ibid]

[57] Shach 121:11

[58] See Taz 91:2; Rashal Kol Habasar 44

[59] See Rama 105:1; Chapter 8 Halacha 7!

[60] This, however, only applies if the counter has been used in the past for hot meat, or has been washed with hot meat, or has had meat soak in it for 24 hours. Otherwise, the counter remains Kosher and is now dairy.

[61] See Chapter 8 Halacha 18B-C!

[62] See Aruch Hashulchan 89:16; Kaf Hachaim 89:79; Admur 451/2; Shach 91/3; Hakashrus 2:1-6; 35-49

[63] The reason: As chinaware and cutlery are also used for hot foods and thus contains absorbed taste which can become absorbed in other foods that they are used with, and hence have the same status as cookware explained above. If the vessel is Ben Yomo, then hot foods placed in it absorb the taste within that vessel. Furthermore, even if the vessel is not Ben Yomo, it is nevertheless initially forbidden to cause non-Ben Yomo taste to get absorbed. Furthermore, even if one places cold food in the vessel, if the food contains liquid and remains there for 24 hours, it absorbs the taste. Now, although after the 24-hour soaking period the taste is certainly not Ben Yomo, it is nevertheless initially forbidden to do so.

[64] The reason: Although it suffices to Kosher a vessel used for only cold Issur through simply rinsing it [Michaber Y.D. 121:1; Admur 451:43 regarding Pesach; Taz 91:3], nonetheless, regarding back and forth use of cold Basar Bechalav there is reason to be stricter, as one may forget to wash the plate prior to its next use, or will wash it with hot water and make it non-Kosher, or have it soak in the sink for 24 hours together with the opposite dishes. This follows the ruling of Michaber 91:2 that whenever washing is required, we suspect one may forget to wash off the substance, and it is hence initially forbidden to be done even if one plans to wash it. Thus, this case is not similar to the case of allowance discussed above to permit the occasional use of non-Kosher plates for Kosher food, as here one plans to reuse the plate for the opposite food, and if one is not accustomed to wash the plate with cold water as soon as one is done eating, there is worry that one may forget and come to transgress. There are many instances in Poskim that we find a stricter approach to meat and milk than to even actual non-Kosher due to the greater possibility of mix-up and confusion. See Shach 89:22 and P”M 89 S.D. 22 regarding cutting cheese with a meat knife that had Neitza performed; See M”A 509:11 regarding Koshering from meat to milk. However, Tzaruch Iyun, as according to this one should also not share glass vessels between meat and milk, and the custom of even Ashkenazim is to be lenient in this, as brought in the section regarding “Glass.” [See Mishneh Halachos 9:168; Yabia Omer Y.D. 4:5 that we do not suspect that one will not clean it well] Nonetheless, practically, by non-glass materials there are other worries relevant, such as that one may come to use it with hot food and thus prohibit the plate and food, and thus the custom is to avoid using the vessels for both meat and dairy and only by glass are we lenient. 

[65] Aruch Hashulchan 89:16 and Kaf Hachaim 89:79 that the dairy set of plates is to be marked in order to distinguish it from the other set and that so is the custom of all Israel.

[66] See Poskim ibid and Rama 89:4 that the custom of Jewry is to make a mark specifically on the dairy utensils; See Darkei Teshuvah 89:54 that one is not to swerve from this custom, and is to specifically mark the dairy vessels, as if one marks the meat vessels it can cause confusion amongst others. See there for other details of this custom; See Sefer Kur Hamivchan Teshuvah 41; Hakashrus 2 footnote 5

[67] Mishneh Halachos ibid regarding plates and cups

The reason: This is different than the ruling by Chametz as As a) Chametz contains many stringencies that we do not apply towards other Issurim. b) Meat and milk are independently Kosher and can only become Biblically forbidden if cooked together. Thus, the issue of using glass plates and cups for both meat and milk is only a Rabbinical prohibition, and by a Rabbinical doubt we are lenient. Furthermore, the use of glass plates and cups is at its best a case of Nat Bar Nat Diheteira. [Mishneh Halachos ibid] c) See Yabia Omer Y.D. 4:5 in great length that we do not suspect that one may come to not clean the vessel properly.

[68] Maharam Shick Yoreh Deah 141 regarding glass cups of Issur; Sdei Chemed ibid 30; Shevilei David Y.D. 121:6 [stringent against using for hot foods by opposite meal]; See all Poskim below regarding Pyrex who rule that by other Issurim we may only be lenient to Kosher the glass, but not to use without Koshering [However, it is unclear if these Poskim would apply their stringency only to glass cookware or even to glass cups]; See M”A 451:48; Minchas Yitzchak 1:86; Chelkas Yaakov 2:163 [not to allow an egg with blood to soak in a glass vessel]; Hakashrus 2:35; 38 footnote 69

[69] See Hakashrus 2:35; 38 footnote 69

[70] See Mishneh Halachos ibid “I heard from one Gadol that when his wife desired to purchase a set of glass cups for meat and a set of glass cups for milk, he protested against her doing so stating that his mother did not keep such a Chumra, and she had a house visited by the Geonei and Tzadikei Hador, and so was practiced in the homes of other Gedolei Yisrael of the previous generation, and hence I do not want to swerve from the custom of my mother’s house.”

[71] Yabia Omer 4:5; Chazon Ovadia Hagala 8

[72] Hakashrus 2 footnote 68 that so is the consensus of the Poskim that the glaze does not prevent the earthenware from absorbing and expelling taste; See Admur 451:75 that a glass coated vessel is judged like glass Lechumra [but not necessarily Lekula]

[73] See previous footnote for why this should not initially be done even though by other Issurim, we do allow even initially for one to use a clean non-Kosher plate for Kosher food on occasion, as explained in Poskim in next footnote.

[74] So rule regarding using a Chametz or non-Kosher vessel: Admur 451:2; 450:13; Shach 91:3; Peri Chadash 91:3; Peri Toar 91:2; Kehilas Yehuda 91:2; Batei Kehuna 1:18; P”M 91 M.Z. 3; Zivcheiy Tzedek 91:5 and 12; Kaf Hachaim 91:5-7, 14

Other opinions: Some Poskim , however, limit this allowance specifically to plates made of Kosherable material [i.e. metal], while plates made of non-Kosherable material [i.e. earthenware; bone, chinaware, pottery] may not initially be used even if they are clean, if they have ever been used with hot non-Kosher foods.  [Peri Chadash 91:3; Peri Toar 91:2; Minchas Yaakov 11:6; Batei Kehuna 1:18 p. 93; Kehilas Yehuda 91:2;  P”M 91 S.D. 3; Erech Hashulchan 91:2; Chochmas Adam 56:2; Zivcheiy Tzedek 91:5; Kaf Hachaim 91:7] Other Poskim  differentiate between plates that have only been used for cold non-Kosher foods, and plates that have been used for also hot non-Kosher foods. If the plate has been used for only cold non-Kosher foods, then it may be used for all Kosher foods, whether moist  or dry. If, however, the plate has been used for hot non-Kosher foods, then it may not be used for moist Kosher foods. [Rama 91:2; Taz 91:3; Although the Rama and Taz do not make it clear regarding whether they are referring to a clean or dirty plate, seemingly, they must be referring to a clean plate, as if the plate is dirty, it makes no difference if it has been used for hot or cold, and either way one may not initially place moist Kosher foods on it. Vetzaruch Iyun!] Practically, we rule like the first opinion that on occasion, it is permitted to place [non-Charif] Kosher foods on top of a clean [and washed] non-Kosher plate even if the food is moist and even if the plate has been used for hot non-Kosher foods in the past. This applies even to earthenware. [Poskim ibid]

[75] See Michaber Y.D. 121:1; Admur 451:43 regarding Pesach; Taz 91:3 regarding vessels that have never been used for hot

[76] Shach 121:11

[77] See Taz 91:2; Rashal Kol Habasar 44

[78] If the meat and milk that became mixed are both liquids, then the mixture is permitted if it contains 60x. If, however it is a solid with a solid/liquid then see regarding mixtures of Yaveish Belach that they are never nullified: Taz 104:1; Shach in Nekudos Hakesef ibid; Admur 442 Kuntres Acharon 15; 466:9-11; Shut Rabbeinu 18; Tzemach Tzedek in Piskeiy Dinim 104 p. 189:b; Shutim Yoreh Deah 70:4; See Piskeiy Admur Yoreh Deah chapter 100

[79] See Rama 105:1; Chapter 8 Halacha 7!

[80] This, however, only applies if the vessel has been used in the past for hot meat, or has been washed with hot meat, or has had meat soak in it for 24 hours. Otherwise, the vessel remains Kosher and is now dairy.

[81] See Chapter 8 Halacha 18B-C!

[82] Thus, if other vessels are not available, one can use a dairy spoon to eat a less than Yad Soledes Pareve soup that is in a clean meat bowl.

[83] See Hakashrus 2:60-63

[84] Rama 88:2; P”M 88 S.D. 6; Beis Yitzchak 88:6; Zivcheiy Tzedek 88:19; Kaf Hachaim 88:22

[85] Shach 88:8; Issur Viheter 1:14; Darkei Moshe 88; Kneses Hagedola 88:7; Peri Chadash 88:7; Lechem Hapanim 88:9; Beis Lechem Yehuda 88:10; Minchas Yaakov 77:24; Beis Yitzchak 88:9; Aruch Hashulchan 88:11; Zivcheiy Tzedek 88:24; Kaf Hachaim 88:27

[86] Aruch Hashulchan 88:11; Kaf Hachaim ibid

[87] Implication of Poskim ibid

The reason: Seemingly, the reason for this is because cup are usually used for cold drinks, and hence would not pose an issue of transfer of taste.

[88] As some Poskim rule a Keli Sheiyni can absorb and if one drinks from it with residue of the opposite food in his mouth it can prohibit the drink and cup, if the cup is Ben Yomo and the residue enters the liquid.

[89] Kneses Hagedola Y.D. 121:25 [that even the Machmirim are only stringent regarding Pesach], recorded in P”M 451 M”Z 31 [see Minchas Yitzchak 1:86]; Kehal Yehuda Y.D. 121 “Regarding other Issurim the custom is not to be stringent at all”; Yad Yehuda Y.D. 69 Aruch 89 Katzar 17; Shevilei David Y.D. 121:6 [lenient to use for cold foods by opposite meal]; Aruch Hashulchan Y.D. 121:2 “So is the widespread custom to buy all forms of glass vessels from gentiles and use them without Koshering.”; Poskim in Darkei Teshuvah Y.D. 121:2; Mishneh Halachos 9:168 “The world is accustomed to use it for meat and milk and since this is the case, leave them be, as if they are not prophets they are the son of prophets.”; Teshuvos Vehanhagos 1:432; Yabia Omer 4:41; Sefer Hakashrus ibid; See supplement regarding Kitchen utensils and appliances in end of Sefer for other opinions

[90] See Mishneh Halachos ibid “I heard from one Gadol that when his wife desired to purchase a set of glass cups for meat and a set of glass cups for milk, he protested against her doing so stating that his mother did not keep such a Chumra, and she had a house visited by the Geonei and Tzadikei Hador, and so was practiced in the homes of other Gedolei Yisrael of the previous generation, and hence I do not want to swerve from the custom of my mother’s house.”

[91] See Hakashrus 2:10-13

[92] See Admur 451:19; 50 and M”B 451:56 regarding crevices in wood vessels and that we avoid Koshering them and the same would apply by cutting boards.

[93] See Admur 451: 50 regarding crevices in wood vessels that from the letter of the law, they are defined as cleanable!

[94] See all Poskim brought next regarding Bedieved, and hence certainly one must initially avoid doing so even in a time of need.

[95] This applies if it has been used to cut hot dairy, or is washed with hot dairy, otherwise it is viewed as Pareve which has now become meaty.

[96] See Chapter 8 Halacha 18B-C regarding a clean Ben Yomo surface and 11B regarding Tatah Gavar if the surface was dirty!

[97] See Taz 91:2; Rashal Kol Habasar 44

[98] See Chapter 5 Halacha 3 in Q&A!

[99] See Chapter 8 Halacha 2C; Practically, everyone agrees that if the food contains 60x any possible residue, then everything is permitted. Vetzaruch Iyun regarding mixtures of Yaveish Belach!

[100] The reason: As Ein Machzakinan Issura, as well as that the soap makes the food be Pagum.

[101] See Hakashrus 1:7

[102] Leaving a meat and dairy utensil together enters one into the issue of Kavush, as the vessels are wet and if they remain in that position for 24 hours while wet, there can be transfer of taste. Nevertheless, Bedieved there is no need to worry of this as a) By the time the 24 hours are up, most likely the vessels will be dry. b) By the time the 24 hours arrive, the vessels are no longer Ben Yomo. Nonetheless, Lechatchilah, it is to be avoided.

[103] In the IDF, the Kashrus supervisor examines the cutlery prior to each meal to make sure there is no mix-up of vessels.

[104] If the Pareve utensil soaks in meat or dairy residue for 24 hours, it is no longer considered Pareve. This certainly applies if hot water is poured inside, or one washes the dishes in hot water.

[105] See Hakashrus 1:71-77; Hakashrus Behalacha p. 141; Article of Rav Yisrael Rozen of Tzomet published in Techumin 11:130; Igros Moshe O.C. 1:104; Y.D. 2:28-29; Y.D. 3:10-11, 13; O.C. 3:58; Beir Moshe 7 Kuntres Elektri 60

[106] Beir Moshe 7 Kuntres Elektri 60; Hakashrus ibid; Hakashrus Behalacha p. 141

[107] See Igros Moshe ibid and Rav Ovadia Yosef in coming footnotes who permit using it one after the other; However, see article of Rav Rosen ibid

[108] See Igros Moshe ibid; Hakashrus 1:73; Kashrus Bamitbach Hamoderni 2:1-6; 3:10-11

The reason: One who washes both meat and dairy dishes simultaneously in a dishwasher potentially prohibits everything there, as the leftover meat and dairy foods, and Ben Yomo status of the vessels, cause a forbidden mixture and cooking of tastes. [Dishwashers typically heat the water to 140 degrees Fahrenheit and the water is heated within the dishwasher itself. However, perhaps the spraying water can be viewed as Iruiy Keli Rishon and hence be permitted according to the Rama, and according to the final ruling, in a case of great loss, as explained in Chapter 8 Halacha 30D. However, see article of Rav Rozen that many dishwashers have the status of a Keli Rishon as they have a heating element inside.] Furthermore, it possibly also transgresses the Biblical prohibition against cooking Basar Bechalav. [See Igros Moshe Y.D. 2:28-29; Hakashrus 1:73; Kashrus Bamitbach Hamoderni 2:1-6; 3:10-11]

Other opinions: Some write that those who are lenient to wash both meat and dairy vessels in the dishwasher simultaneously have upon whom to rely. [Rav Yitzchak Yosef in Otzer Dinim Laisha Ulabat 30:15; Hakashrus 1 footnote 137 in name of Rav Ovadia Yosef, although I could not find his source in the Sefer Hakashrus Behalacha which he references to, and on the contrary, that Sefer writes in the name of Rav Ovadia that one may use it one after the other, and makes no mention of using it simultaneously. Nevertheless, in essence there is some truth to the statement, as according to the Michaber 95:4, if a spoiling agent is added to the water, meat and dairy dishes may be washed simultaneously in a Keli Rishon. Furthermore, perhaps one can judge a dishwasher as Iruiy Keli Rishon rather than Keli Rishon, as the water is sprayed. Vetzaruch Iyun, as many dishwashers have coils within the actual washer which heat the water, and perhaps the cycle which sprays clean hot water without soap to clean the soap off the vessels, loses the above leniency of a spoiling agent even according to the Michaber. See article of Rav Rosen who explains that these Rabbanim who gave their lenient rulings were unaware of how the machine works, and that in today’s machines it is judged as an actual Keli Rishon, as they contain coils inside, and the food does not become Pagum due to the soap, and there is no 60x when the water drains out, and other facts that the Rabbanim were unaware of today.]

[109] Based on different Teshuvos of Igros Moshe ibid, as compiled in article of Rav Rosen; Hakashrus and Kashrus Kehalacha ibid

[110] Rav Moshe in Igros Moshe Y.D. 2:28 writes to have separate dish wracks for meat and milk

[111] Hakashrus 1:74 as such materials are not Kosherable; See Igros Moshe O.C. 3:58 regarding Pesach that it is not Kosherable, however Rav Moshe never made this distinction when using from meat to milk

[112] See Igros Moshe ibid in various Teshuvos on the basis that it is Nat Bar Nat Diheteira [the vessels to the water to the dishwasher] as there is usually 60x versus the residue.

[113] See Yad Avraham ibid

[114] The reason: As there is no Safek here, as we know for sure it was washed with meat dishes in Yad Soledes water in a Keli Rishon. [Dishwashers typically heat the water to 140 degrees Fahrenheit and the water is heated within the dishwasher itself. However, perhaps the spraying water can be viewed as Iruiy Keli Rishon and hence be permitted according to the Rama, and according to the final ruling, in a case of great loss, as explained in Halacha 8. However, see article of Rav Rosen who explains that these Rabbanim who gave their lenient rulings were unaware of how the machine works, and that in today’s machines it is judged as an actual Keli Rishon, as they contain coils inside, and the food does not become Pagum due to the soap, and there is no 60x when the water drains out, and other facts that the Rabbanim were unaware of today.]

[115] Now although a Stam vessel that is being washed is dirty, as explained in Shach 95:1, nevertheless here if one does not know for sure the vessel is dirty one may be lenient as perhaps the leftover residue became spoiled due to the soap or other spoiling agent. Nevertheless, there are Poskim who in truth learn that the vessel is only permitted if one knows for certain that it was clean. [Yad Avraham]

[116] Igros Moshe Y.D. 3:58; Hakashrus 1:77

[117] Igros Moshe ibid

[118] See Igros Moshe ibid that initially the water is to reach boiling point although if not possible, it suffices if it reaches a hotter temperature than usual; See Igros Moshe 3:29 that his son, Reb David, suggested that there is no need for running a cycle of hot water for Hagala, and it suffices for 24 hours to pass, as it is similar to the allowance to Kosher non-Ben Yomo vessels in less than 60x water. Rav Moshe negated this by saying that this is only required when it comes to Koshering, however, when it comes to washing dishes and other food related matters, the Sages decree non-Ben Yomo versus Ben Yomo. [Brought in Hakashrus 1 footnote 145]

[119] Igros Moshe O.C. 3:58; Hakashrus 1:74 as such materials are not Kosherable; Koveitz Mibeis Levi 1:30

[120] Hakashrus 1:55-57

[121] Michaber 95:6

The reason: As people are extra careful with meat and milk to avoid them from coming into contact with each other when they are close together. [Shach 95:23; Taz 95:17; Beis Yosef 95; Peri Chadash 95:22; Kaf Hachaim 95:66]

[122] Rama 95:6

[123] Shach 95:24; Minchas Yaakov ibid; Zivcheiy Tzedek 95:45; Kaf Hachaim 95:67

[124] Peri Chadash 95:23; Zivcheiy Tzedek 95:47; Kaf Hachaim 95:68; See Admur Kuntres Acharon 442:15; Piskeiy Yoreh Deah p. 207

[125] See Hakashrus 1:82-85

[126] See chapter 1 Halacha 2A regarding burning garbage that contains meat and milk and the reasons that it is permitted and the same would apply towards pouring hot meat or milk into the garbage.

[127] Hakashrus 1:84; See also Yad Avraham ibid; However by wild animal meat or poultry, there is no cooking prohibition. As well by cold foods there is no cooking prohibition even if it will become Kavush.

[128] See Admur 451:73; Michaber 451:26; Darkei Teshuvah Y.D. 121; Sdei Chemed Mareches Hei 29; Hakashrus 2:38 footnote 69; 3:52-54; Koveitz Hearos 770 Yud Shevat 5771

[129] 1^st and Stam opinion in Admur ibid; Michaber ibid and final ruling of Beis Yosef 451:26; Michaber Y.D. 135:8 and Taz 135:11 regarding Yayin Nesech; Ravayah 464; Rashba 1:233; Ran 2:9

[130] Admur ibid

[131] Bedieved opinion in Admur ibid and M”A 451:49; See P”M 451 A”A 49 that the M”A ibid holds glass is Kosherable; Or Zarua Pesachim p. 58 [115] in Pirush of Rav Shmuel Miplaish to Piyut of Elokei Haruchos “Glass..if it was used with hot it suffices with Hagala as they are only similar to earthenware regarding Tuma, however regarding Hagala they are like metal.”; See also Shibulei Haleket; Ritva Pesachim in name of Reah

[132] 2^nd opinion in Admur; Rama ibid; Mordechai 574; Semag L.S. 78; Iggur 737 and Hagahos Maimanis 5 in name of Yechiel Miparish; Terumos Hadeshen 1:132

[133] See Darkei Teshuvah Y.D. 121:2

[134] Admur ibid; Rama ibid; Iggur ibid

[135] Kneses Hagedola Y.D. 121:25 [that even the Machmirim are only stringent regarding Pesach], recorded in P”M 451 M”Z 31 [see Minchas Yitzchak 1:86]; Kehal Yehuda Y.D. 121 “Regarding other Issurim the custom is not to be stringent at all”; Yad Yehuda Y.D. 69 Aruch 89 Katzar 17; Shevilei David Y.D. 121:6 [lenient to use for cold foods by opposite meal]; Aruch Hashulchan Y.D. 121:2 “So is the widespread custom to buy all forms of glass vessels from gentiles and use them without Koshering.”; Poskim in Darkei Teshuvah Y.D. 121:2; Mishneh Halachos 9:168 “The world is accustomed to use it for meat and milk and since this is the case, leave them be, as if they are not prophets they are the son of prophets.”; Teshuvos Vehanhagos 1:432; Yabia Omer 4:41; Sefer Hakashrus ibid; See Hakashrus 3:53 that the Ashkenazi custom is to be lenient to Kosher them; See Admur 87:2 regarding a glass potty and in Kuntres Acharon 87:2 “In 451 it is only an initial stringency”; See M”A 451:48 who contrasts the stringency of Chametz to the leniency by Yayin Nesech “Although we are stringent by Chametz, do not compare it to Yayin Nesech, as many leniencies apply by Yayin Nesech and not by Chametz”

[136] Mishneh Halachos ibid regarding plates and cups, however not regarding tempered glass used for cooking [duralex/pyrex], as explained next

The reason: As a) Chametz contains many stringencies that we do not apply towards other Issurim. b) Meat and milk are independently Kosher and can only become Biblically forbidden if cooked together. Thus, the issue of using glass plates and cups for both meat and milk is only a Rabbinical prohibition, and by a Rabbinical doubt we are lenient. Furthermore, the use of glass plates and cups is at its best a case of Nat Bar Nat Diheteira. [Mishneh Halachos ibid] c) See Yabia Omer Y.D. 4:5 in great length that we do not suspect that one may come to not clean the vessel properly.

[137] Maharam Shick Yoreh Deah 141 regarding glass cups of Issur; Sdei Chemed ibid 30; Shevilei David Y.D. 121:6 [stringent against using for hot foods by opposite meal]; See all Poskim below regarding Pyrex who rule that by other Issurim we may only be lenient to Kosher the glass, but not to use without Koshering [However, it is unclear if these Poskim would apply their stringency only to glass cookware or even to glass cups]; See M”A 451:48; Minchas Yitzchak 1:86; Chelkas Yaakov 2:163 [not to allow an egg with blood to soak in a glass vessel]; Hakashrus 2:35; 38 footnote 69

[138] See Hakashrus 2:35; 38 footnote 69

[139] See Mishneh Halachos ibid “I heard from one Gadol that when his wife desired to purchase a set of glass cups for meat and a set of glass cups for milk, he protested against her doing so stating that his mother did not keep such a Chumra, and she had a house visited by the Geonei and Tzadikei Hador, and so was practiced in the homes of other Gedolei Yisrael of the previous generation, and hence I do not want to swerve from the custom of my mother’s house.”

[140] Yabia Omer 4:5; Chazon Ovadia Hagala 8

[141] See Piskeiy Teshuvos 451:54

[142] The reason for differentiation: 1) The glass that was around in the times of the Talmud and Poskim was not heat resistant and hence would never be placed on a fire for cooking. Accordingly, perhaps the leniencies stated in the Poskim regarding glass only applied towards glass that was not used over a fire, while heat resistant glass would be more stringent and require Koshering according to all. 2) In addition, some Poskim raise the fact that in the manufacturing of Pyrex company heat resistant glass, a small percentage of aluminum is added, thus changing the equation of the entire leniency mentioned in Poskim relevant to pure glass. 3) In addition, many Poskim rule that the custom is to prohibit switching usages between meat and milk even if one Koshers the vessel in between as one may come to forget to Kosher it, and the same should apply here, as one may forget to clean the vessel.

[143] Tuv Taam Vedaas 2:25 [regarding glass lamps of Cheilev]; Maharam Shick Yoreh Deah 141; Yaskil Avdi 4:13; Tzitz Eliezer 8:21; 9:26; Shearim Hametzuyanim 126:11; Minchas Yitzchak 1:86; Beis Avi 1:115; Yesod Yeshurun 6:170; Shraga Hameir 7:143; Shevet Halevi 2:43; Mishneh Halachos ibid “Since they cook on the fire Chas Veshalom to be lenient and meat and milk even one after the other”; Siddur Pesach Kehilchaso 9 footnote 27 in name of Rav Elyashiv; Rav Mordechai Eliyahu, brought in Sefer Hakashrus 2:20; ibid footnote 148; See all Poskim regarding Bedieved; Piskeiy Teshuvos 451:54

Bedieved, if glass cookware used with non-Kosher or meat and milk-May the cookware be Koshered? Yes, it may be Koshered through Hagala. [Poskim ibid; Maharam Shick ibid; Minchas Yitzchak ibid; Tzitz Eliezer ibid] See article of Rav Braun in Koveitz Hearos ibid who concludes it cannot be Koshered even by other Issurim.

[144] The reason: 1) As cooking on glass is more severe than the case discussed in the Shulchan Aruch which only involved using glass cups and plates, while here the food is actually cooked in the glass on the fire, and is a question of a Biblical prohibition. [See Poskim ibid; Mishneh Halachos ibid] 2) Alternatively, as Pyrex and Duralex glass contains metal additives to the formula and hence it does not have the same status and leniency as regular metal. [Tzitz Eliezer ibid] 3) As, many Poskim rule that the custom is to prohibit switching usages between meat and milk vessels even if one Koshers the vessel in between as one may come to forget to Kosher it [M”A 509:11], and the same should apply here, as one may forget to clean the vessel. [Rabbanim brought in Yabia Omer Y.D. 4:5; The Yabia Omer discusses [only] this point throughout his Teshuvah, and after analyzing all the opinions, concludes that we do not suspect for it]

[145] Yechaveh Daas 1:6; Yabia Omer Y.D. 4:5 [discusses only the third issue mentioned above, and after analyzing all the opinions, concludes that we do not suspect for it]

[146] Pashut! See Hakashrus 2 footnote 69

[147] Hakashrus 2 footnote 68 that so is the consensus of the Poskim that the glaze does not prevent the earthenware from absorbing and expelling taste; See Admur 451:75 that a glass coated vessel is judged like glass Lechumra [but not necessarily Lekula]

[148] See Hakashrus 1:28

[149] See Hakashrus 2:14-15

[150] It is very difficult to clean a grater, and it hence does not follow the leniency brought regarding knives in a time of need.

[151] As possibly the peeler has been washed with hot water with the meat or dairy dishes, and/or stayed in liquid for 24 hours.

[152] The reason: As people do not usually grate hot Yad Soledes meat/dairy with a grater, and one can assume that there is 60x versus any residue. See Chapter 5 Halacha 3 in Q&A!

[153] See Hakashrus 2:16-17

[154] See Hakashrus 2:25-27

[155] See Admur 451:50 that flour vessels are difficult to clean.

[156] See Admur ibid that the above worry that leftover flour/dough remains is only a stringency.

[157] Rashal Kol Habasar 8; Kneses Hagedola 89:16; Peri Chadash 89:24; Lechem Hapanim 89:29; Beis Lechem Yehuda 89:20; Birkeiy Yosef 89 Shiyurei Bracha 42; Aruch Hashulchan 89:16; Zivcheiy Tzedek 89:47; Kaf Hachaim 89:75

[158] Hakashrus 2:4

[159] Michaber 89:4; See Hakashrus 2:44

[160] Nekudos Hakesef on Taz 89:6

[161] See Shach 89:22 and P”M 89 S.D. 22

[162] Michaber 89:4; Teshuvah Ramban 172

The reason: As we suspect there is fat leftover on the blade of the knife which will then get onto the cheese. [Nekudas Hakesef 89]

[163] Rama ibid

[164] Rama 89:4

[165] Rama ibid and Taz ibid only permit with Neitza; Admur 451:2 regarding using Chametz knife for Pesach; Michaber Y.D. 121:7 regarding using non-Kosher knife for Kosher

[166] Taz 89:6 “However, regarding cutting bread, only a cleansing of the knife is required” and 89:7 “According to the custom, one may not use the knife to cut cheese even if Neitza is performed, however in my opinion, he may use it to cut bread if it is cleaned”; Implication of Beis Yosef 89 in name of Orchos Chaim in name of Rabbeinu Shimshon; Halacha Pesuka 89; Chochmas Adam 40:14; Aruch Hashulchan 89:16

Serrated knife: See Michaber 121:7 who differentiates between serrated and non-serrated knives and that a non-serrated knife requires sharpening or Libun to be allowed to be used with cold foods; Vetzaruch Iyun on Poskim ibid who make no mention of any differentiation.

[167] See Chapter 96

[168] Meaning even if there is no pressing need to do so. [Taz 89:7]

[169] Taz 89:7

The reason: As the custom of Jewry was only against using the meat knife to cut actual cheese, and not against using it to cut Pareve. [Taz ibid “So appears obvious to me”]

[170] Shach 89:22; Nekudas Hakesef ibid “Even to cut bread to eat with cheese requires Neitza”; Toras Chatas 76:6; P”M 89 S.D. 22; Kneses Hagedola 89:16; Toras Yekusiel; Beis Yitzchak 89:7

Contradiction in Shach: Tzaruch Iyun from Shach 96:6 and 21 where he writes that if a meat knife is clean [and not Ben Yomo-6, although in 22 implies even if it is Ben Yomo] then a Pareve food that was cut with it may be used for dairy even without washing it in the interim, while here the Shach ibid writes that it may not be used! However, in truth, there is no contradiction at all as the entire law here is going on Lechatchilah if one may use a clean meat knife for Pareve that will be used for dairy and on this the Shach rules that it may not. However, Bedieved, everyone agrees that the Pareve food remains permitted to be eaten with dairy so long as the knife was clean. [See Beis David Y.D. 35; Shulchan Gavoa 1; Zivcheiy Tzedek 89:45; Kaf Hachaim 89:68]

[171] Shach 89:22; Nekudas Hakesef ibid; P”M 89 S.D. 22

[172] See Kaf Hachaim in next footnote

[173] P”M 89 M.Z. 7; Kaf Hachaim 89:72 if can’t do Neitza; Kitzur Shulchan Aruch 46:12 rules one may not initially use even a clean knife to cut bread [i.e. Shach], although in a time of need one may be lenient to do so [i.e. Taz]; Hakashrus 10:18 writes that in a time of need one may clean the knife to use it to cut bread. See Hakashrus 10:87 he writes that today we consider a knife to be clean when washed with soap, and thus if the knife is clean, a Pareve food which was cut with that knife may be eaten with the opposite food even if the knife did not have Neitza done. One is not required to wash the Pareve food.

[174] The definition of Neitza: Neitza is the act of stabbing a knife into ten different areas of hard ground. [Michaber 10:3; 121:7; Beis Hillel 89:3; Soles Lamincha in end of Toras Chatas 76:7; Birkeiy Yosef 89 Shiyurei Bracha 41; Zivcheiy Tzedek 89:46; Kaf Hachaim 89:70, unlike Chaguras Shmuel who rules that one time suffices]

[175] Taz 89:6 in his understanding of Rama 89:4; Beis David Y.D. 35; Shulchan Gavoa 1; Zivcheiy Tzedek 89:45; Kaf Hachaim 89:68 and 73; Admur 451:2 regarding using Chametz knife for Pesach on occasion; Michaber Y.D. 121:7 regarding using non-Kosher knife for Kosher on occasion

[176] Serrated knife: See Michaber 121:7 who differentiates between serrated and non-serrated knives and that a non-serrated knife requires sharpening or Libun to be allowed to be used with cold foods; Vetzaruch Iyun on Poskim who make no mention of any differentiation.

[177] Taz 89:7

Other opinions: Some Poskim rule it is even initially permitted to cut cheese with a meat knife that had Neitza performed to it. [Beis David Y.D. 35; Shulchan Gavoa 1; Zivcheiy Tzedek 89:45; Kaf Hachaim 89:68] This applies even according to the custom, as in such a case one is doing an action to Kosher it and the custom is only regarding one who already has purchased a dairy knife and has it available. [Kaf Hachaim 89:74; Vetzaruch Iyun as to his intent]

[178] Implication of Shach 89:22; P”M 89 S.D. 22; Beis Yitzchak 89:30

Understanding of Shach: The Shach 89:22 learns that the allowance of Neitza brought in Rama ibid only refers to the cutting bread. This implies that to cut actual cheese would be forbidden according to the Rama even if Neitza is performed, and so learns Peri Megadim S.D. 89:22 in Shach]

[179] The reason: Although we permit one to use even a Treif knife if Neitza was performed, we are more stringent by meat and milk as we suspect that one may come to use it without performing Neitza. [P”M ibid]

[180] Regarding Charif foods, see chapter 96 Halacha 3 in Q&A!

[181] Rama 89:4; Shach 89:22; Nekudas Hakesef ibid “Even to cut bread to eat with cheese requires Neitza”; Toras Chatas 76:6; Peri Chadash 89:23; Minchas Yaakov 77:18 that so applies even according to Rashal; P”M 89 S.D. 22; Kaf Hachaim 89:71; This certainly applies according to Taz ibid and all Poskim who rule like him that even Neitza is not required

Other opinions: Some Poskim rule it is forbidden to use a meat knife to cut even Pareve foods which he plans to eat with cheese even if Neitza is performed, and even if no other knife is available. [Rashal Kol Habasar 8, brought in Shach and Nekudos Hakesef ibid; However, see Minchas Yaakov ibid]

[182] Shach 89:22; Nekudas Hakesef ibid; P”M 89 S.D. 22

[183] Shach ibid

[184] Taz 89:6 and so rules Chachmas Adam 40:14; unlike the Shach ibid

[185] Meaning even if there is no pressing need to do so. [Taz 89:7]

[186] Taz 89:7

The reason: As the custom of Jewry was only against using the meat knife to cut actual cheese, and not against using it to cut Pareve. [Taz ibid “So appears obvious to me”]

[187] See Kaf Hachaim in next footnote

[188] P”M 89 M.Z. 7; Kaf Hachaim 89:72 if can’t do Neitza; Kitzur Shulchan Aruch 46:12 rules one may not initially use even a clean knife to cut bread [i.e. Shach], although in a time of need one may be lenient to do so [i.e. Taz]; Hakashrus 10:18 writes that in a time of need one may clean the knife to use it to cut bread. See Hakashrus 10:87 he writes that today we consider a knife to be clean when washed with soap, and thus if the knife is clean, a Pareve food which was cut with that knife may be eaten with the opposite food even if knife did not have Neitza done. One is not required to wash the Pareve food.

[189] The following Poskim rule that if Pareve was cut with a clean meat knife, and one desires to eat the Pareve with dairy, rinsing is required: Beis David Y.D. p. 18; Yad Yehuda Aruch 96:4 and 34; Katzar 96:35; Zivcheiy Tzedek 96:40; Kaf Hachaim 96:59; Likewise, the following Poskim rule that if one cut meat using a clean Cheilev knife, nevertheless, washing is required: Chavas Daas 91:2; Erech Hashulchan 91:1; Pischeiy Teshuvah 91:1; Beis Yitzchak ibid; Zivcheiy Tzedek 91:3; Kaf Hachaim 91:3

Other opinions: Some Poskim imply that even rinsing is not required, being that the knife was clean. [Implication of Taz 89:6 and 89:7; Hakashrus 10:87]

[190] Beis David Y.D. 35; Shulchan Gavoa 1; Zivcheiy Tzedek 89:45; Kaf Hachaim 89:68; See Shach 96:6 and 22; See Hakashrus 10:87 that today we consider a knife to be clean when washed with soap, and thus if the knife is clean, a Pareve food which was cut with that knife may be eaten with the opposite food even if knife did not have Neitza done. One is not required to even wash the Pareve food.

[191] See Rama 94:7 regarding meat of a Keli Sheiyni that was cut with a dairy knife that it requires a slight Kelipa to be removed due to the fat that is on the knife. [Vetzaruch Iyun on Rama who agrees to the ruling in 96:5 that if a Pareve food was cut with a dirty meat knife it at most only needs Greida, and not a Kelipa.]; However, the Poskim in next footnote write that Kdei Netila is to be removed. On the other hand, other Poskim rule that if one cut meat using a dirty Cheilev knife, only washing and rubbing is required, and not even Greida or Kelipa. [Chavas Daas 91:2; Erech Hashulchan 91:1; Pischeiy Vetzaruch Teshuvah 91:1; Beis Yitzchak ibid; Zivcheiy Tzedek 91:3; Kaf Hachaim 91:3; See 91:1 where we rule that when cheese and meet contact each other they require a mere washing and the above Poskim explain that when there is Duchka Desakina, rubbing is also required.] Vetzaruch Iyun Gadol on the above two opinions as the Rama rules in 94:7 that even if the meat was hot, but a Keli Sheiyni, only a Kelipa’s worth needs to be removed.! [Greida is less than a Kelipa, while Netila is more than a Kelipa. See Shach 96:21; Kaf Hachaim 91:17] Practically, as evident from all the above sources there is no need to remove a Kdei Netila, and rather at the very most a Kelipa is to be removed. 

[192] Shulchan Gavoa 1; Zivcheiy Tzedek 89:45; Kaf Hachaim 89:69

[193] Shach 94:31; Issur Viheter 58:4; Kreisi 94:23; Halacha Pesuka 94:7; Erech Hashulchan 94:15; Chochmas Adam 47:4; Beis Yitzchak 3:18; Zivcheiy Tzedek 94:53; Kaf Hachaim 94:76; Hakashrus 10:88

[194] See Shulchan Gavoa 1; Zivcheiy Tzedek 89:45; Kaf Hachaim 89:69 “One cleans the knife and returns it to its designated use”

[195] Implication of Shach and Poskim ibid; Erech Hashulchan ibid; Zivcheiy Tzedek 94:53; Kaf Hachaim 94:76; However, See Rama 94:7 regarding meat of a Keli Sheiyni that was cut with a milk knife that the knife requires Neitza, however, seemingly this is because the meat was hot, while if cold the Poskim ibid explain that a mere rinse suffices; See Rashal Kol Habasar 8, brought in Shach 89:22 that Neitza is always required

[196] See Hakashrus 10 footnote 225; See Shach and Taz 10:6 regarding the function of Neitza, although clearly in this case its function is simply for cleanliness; See Rabbeinu Shimshon brought in Beis Yosef 89

[197] See Sefer Hayashar of Rabbeinu Tam 790 “Lav Davka Neitza”; Reah 4a; Semak 213

[198] See Sefer Hagalas Keilim 13 footnote 260 Hakashrus 2:44; See Piskeiy Rabbeinu Yechiel Miparitch 47 that sharpening creates Yad Soledes heat

[199] Pashut, as there is no reason to prohibit the use of a sharpener for both meat and dairy knives. Taste cannot transfer from one vessel to another without heat and liquid, and the act of sharpening does not create Halachic heat, and even if it did two dry vessels do not transfer taste even when hot. Furthermore, the Michaber in 121:7 rules that sharpening a Treif knife is a form of Koshering, and thus if it can Kosher a Treif knife, certainly it can be used for sharpening a meat/dairy knife. No mention is ever made in the Poskim that the sharpener must only be used for one form of Kosher knives! Furthermore, the Beis Yosef 122:9-10 brings in the name of the Mordechai Avoda Zara 832 that people would bring their knives to a gentile sharpener, and if the knife was returned within the hour, the knife is Kosher, and no worry is mentioned regarding the sharpener itself having been used for Treif knives.

[200] As if the blade contains Charif residue, it could cause the meat/dairy taste to get absorbed into the vessel, and then back into the knife. See Chapter 5 Halacha 3 in Q&A regarding a cutting board.

[201] See Hakashrus 1:58-67

[202] Hakashrus 1:58

[203] Hakashrus 1:59

[204] If any of the last three conditions are not fulfilled, then the bowl has absorbed meat or dairy taste and thus initially may not be used with the opposite food just as we do not initially use meat cutlery and chinaware for even cold dairy, lest one come to use it for hot dairy.

[205] As so long as the meat or dairy currently being blended is not Yad Soledes, it cannot absorb from the bowl, and in a time of need we are lenient to allow a meat vessel to be used for cold dairy and vice versa, as explained in the section of “Cutlery and chinaware”

[206] As even according to the Taz, one must perform Neitza to be allowed to use the same blades for meat and milk, which is not possible to be done with the blades. See above regarding knives! Vetzaruch Iyun if one can rely on cleaning it and the pouring hot water.

[207] See above Halacha D regarding knives, and Chapter 8 Halacha 2B that Bedieved we do not require Kelipa if it already disintegrated.

[208] See Piskeiy Teshuvos 451:22; Sefer Hakashrus [Fuchs] 1:47-50 [pp. 48-49]; Nitei Gavriel 80:16; See also Hadarom Choveret 6 Nissan 5722; Kovetz Beis Ahron Yisrael 4:3

How does a microwave cook? A microwave is a rapid cooking element, which can warm and cook food much quicker than traditional cooking methods. Now, how does the microwave achieve its rapid cooking? The microwave does not use the heat of a fire or electricity to cook but rather cooks the food using radiation, or radio electromagnetic waves, which is projected from a vacuum tube and bounced off the metal lined walls of the microwave which penetrate the food from all sides. These waves hasten the movement of the water molecules in the food to atomic levels hence generating heat. [Heat is generated from movement and friction.] This form of cooking cooks the food much quicker than fire or electricity, as the radioactive waves hits the food equally in all areas and furthermore, penetrates the inside of the food molecules hence making the entire mass of the food an equal recipient of the heat. This is unlike fire or electric cooking which heats the external part of the food, and that heat then must travel to the inner part of the food in order to cook it. Likewise, this form of cooking only heats the actual food, as it does not actually send heat to the food but causes the food to heat itself up. Accordingly, all other areas and items of the microwave might remain cold, including the walls and certain plastic or glass containers which cover the food. The only way these items will become hot is if they are in contact with the food itself. The radio waves harmlessly pass through these containers into the food and do not cause any heating within them being they do not contain water molecules or other polar charge component. [See Hakashrus ibid footnote 100; See here for an educational video on how a microwave works. https:::www.youtube.com:watch?v=kp33ZprO0Ck]

[209] Rav Yitzchak Yosef

[210] See all Gedolei HaPoskim mentioned in Hakashrus ibid and Piskeiy Teshuvos ibid, which include Rav Wozner, Rav Elyashiv, Rav Sheinberg, Rav Halbershtam; Nitei Gavriel ibid footnote 26 in name of Rav Neiman of Montreal;

[211] The reason: a) Although the walls of the microwave do not heat, nevertheless the steam and spills of the food inside make the walls absorb the food and hence it must be Koshered. [Piskeiy Teshuvos ibid; See Admur 451:41, Michaber 451:14, and M”B 451:81 that a vessel which absorbed the steam of an Issur requires Hagala] b) As there is a vent duct in the microwave that contains actual steam of food, and that area is not Kosherable. [Rav Neiman ibid

[212] As due to the steam it is similar to baking dairy in a modern-day meat oven, which is similar to cooking dairy food in a non-Ben Yomo meat pot, which prohibits the vessel, and is initially forbidden to be done even though the food remains permitted.

[213] As although the walls don’t heat up the microwave receives steam from the foods and hence must be Koshered.

[214] See Admur 447:10; Rama 92:8; Michaber 108:1; Hakashrus ibid; Nitei Gavriel ibid in name of Rav Neiman

[215] Pischeiy Halacha Kashrus p. 28; Piskeiy Teshuvos ibid footnote 106

[216] See Kovetz Mibeis Levi 3:22-9; Hadarom ibid; Beis Ahron Veyisrael ibid

[217] See Piskeiy Teshuvos 451:22; Sefer Hakashrus [Fuchs] 1:47-50 [pp. 48-49]; Nitei Gavriel 80:16; See also Hadarom Choveret 6 Nissan 5722; Kovetz Beis Ahron Yisrael 4:3

How does a microwave cook? A microwave is a rapid cooking element, which can warm and cook food much quicker than traditional cooking methods. Now, how does the microwave achieve its rapid cooking? The microwave does not use the heat of a fire or electricity to cook but rather cooks the food using radiation, or radio electromagnetic waves, which is projected from a vacuum tube and bounced off the metal lined walls of the microwave which penetrate the food from all sides. These waves hasten the movement of the water molecules in the food to atomic levels hence generating heat. [Heat is generated from movement and friction.] This form of cooking cooks the food much quicker than fire or electricity, as the radioactive waves hits the food equally in all areas and furthermore, penetrates the inside of the food molecules hence making the entire mass of the food an equal recipient of the heat. This is unlike fire or electric cooking which heats the external part of the food, and that heat then must travel to the inner part of the food in order to cook it. Likewise, this form of cooking only heats the actual food, as it does not actually send heat to the food but causes the food to heat itself up. Accordingly, all other areas and items of the microwave might remain cold, including the walls and certain plastic or glass containers which cover the food. The only way these items will become hot is if they are in contact with the food itself. The radio waves harmlessly pass through these containers into the food and do not cause any heating within them being they do not contain water molecules or other polar charge component. [See Hakashrus ibid footnote 100; See here for an educational video on how a microwave works. https:::www.youtube.com:watch?v=kp33ZprO0Ck]

[218] See Piskeiy Teshuvos ibid; Siddur Pesach Kehilchaso that 8:3 that it can only be Koshered through Iruiy Keli Rishon and Even Meluban

[219] The reason: a) Although the walls of the microwave do not heat, nevertheless the steam and spills of the food inside make the walls absorb the food and hence it must be Koshered. Now, it is not possible to Kosher the microwave as one cannot blow torch it, place it in boiling water, and many Poskim rule an item cannot be Koshered through steaming water inside it. [See Shoel Umeishiv Telisa 3:125; Sdei Chemed Mareches Hei 24; Chametz UMatzah 17:12 that it is not possible to Kosher through vapor] It therefore has no viable path for Koshering. A second reason is b) As there is a vent duct in the microwave that contains actual steam of food, and that area is not cleanable or Kosherable. [Rav Neiman ibid]

[220] Teshuvos Vehanhagos 2:212; Yalkut Yosef Pesach p. 360; Piskeiy Teshuvos ibid regarding Shaas Hadechak

[221] The reason: As we rule that it is possible to Kosher an item through steam, and just like the microwave absorbed the food through steam, so too it can be Koshered through steam. [See Peri Chadash 121; P”M  Y.D. 94 M”Z 1; Tevuos Hasadeh 3:3]

[222] See Hakashrus ibis footnote 105 that so ruled Rav Wozner, Rav Shternbuch and Rav Mordechai Eliyahu

[223] Piskeiy Teshuvos ibid writes to leave it on for one hour; Sefer Hakashrus ibid writes [based on Mitbach Kehalacha p. 58 and Techumin 8:21] to enter a half a liter of water and leave the microwave on until it steams out; Rav Yitzchak Yosef says to leave it on for six minutes

[224] Teshuvos Vehanhagos 2:212; Koveitz Mibeis Levi 3:22; 7:25; Yalkut Yosef Pesach p. 360; Piskeiy Teshuvos ibid; Hakashrus ibid

[225] Hakashrus 1:62

[226] See Hakashrus 1:31-33; 38-46

[227] See Hakashrus 1:33

[228] See Igros Moshe 1:40

[229] See Maharsham 3:208; Chelkas Yaakov 2:136; Minchas Yitzchak 5:20; Igros Moshe Y.D .1:40; Yabia Omer 5:7; Teshuvos Vehanhagos 1:430; Koveitz Mibeis Levi 3:21; Hakashrus 1:43;

[230] Admur 494:16

[231] Kinyan Torah 1:24

[232] Hakashrus 1:44; An oven with self cleaning mode reaches a temperature of 900° F and is thus equivalent to Libun Chamur. This helps to perform Libun Chamor to itself, as well as to all Kosherable utensils that are placed in it while on a self-cleaning cycle. An oven with a “Continuous cleaning” cycle does not reach this level of heat and is not equivalent to Libun Chamur.

[233] As if one turns on the oven to Kosher it while there is still residue inside, then it reabsorbs the taste of the residue. See Hakashrus 1 footnote 94. Vetzaruch Iyun.

[234] Teshuvos Vehanhagos ibid; Minchas Yitzchak ibid

[235] See Admur 494:16

[236] Hakashrus ibid as some Poskim say the latter materials are non-Kosherable.

[237] Hakashrus 1:45

[238] Hakashrus 1:38

[239] Erech Hashulchan 92:15; Kaf Hachaim 92:103; 108:19; Darkei Teshuvah 108:39; Hakashrus 1:38

[240] The reason: As the vapor which is released from the residue only becomes absorbed in the external covering, and the internal covering does not absorb from the external one, being there is no moisture in-between, and is similar to two dry pots touching each other. [See Taz 92:29; 97:3]

[241] As otherwise there is suspicion one may place the pot of food on top of the residue and hence forbid the pot. Likewise, the residue releases vapor which becomes absorbed within the single external cover of the food, which is moist with the food/vapor of its own, and can hence penetrate into the food.

[242] Kinyan Torah 1:24

[243] Taz 97:4; Peri Chadash 97:4; Chavas Daas 97:9; Aruch Hashulchan 97:12; Kaf Hachaim 97:34]

The reason: As the fat does not clean off well and requires the oven to be lit in order to burn the fat. [Poskim ibid]

[244] Hakashrus 1:45

[245] See however Chelkas Yaakov 2:136 and Hakashrus 1 footnote 78 that we treat the oven as a cover of a pot which has status of Ben Yomo even after 24 hours.

[246] Rama 92:8 and 108:1

[247] There are two possible ways of understanding the prohibition of Zeiah: 1) Due to Nitzuk Chibur [See Admur 451:41 and Levush 93 who learns that the vapor prohibits due to the law of Nitzuk Chibur] 2) Due to Mamashus [See P”M 92 M.Z. 29 and O.C. 441 A.A. 44 and Yad Yehuda 92:52 who learns that the prohibition of Zeiah is due to Mamashus falling back inside.]

[248] A large oven negates a Zeiah concern as a) It dissipates the Zeiah evenly everywhere, and by the time it reaches the oven roof, there may be no vapor left; b) the oven roof would not get hot to the point of Yad Soledes, and the vapor was below Yad Soledes by the time it hit the oven, thus avoid any issue of Zeiah. This applies even if the oven contains no vents during the cooking or baking.

[249] See Igros Moshe Y.D. 1:40 in length for the Zeiah concerns in our ovens and that they have the same status as a pan placed over two uncovered foods, brought in Rama 108:1; Maharsham 3:208; Minchas Yitzchak 5:20; Chelkas Yaakov 2:136; Kinyan Torah 1:24; Badei Hashulchan 92:166; Darkei Halacha p. 242; See Hakashrus 1:31 footnote 61; 38

The reason: As the roofing is very close to the food and it is hence just like the case of a cover on two pots, or to the cover of a meat pot placed onto a milk pot. Now, this prohibition of Zeiah is either due to Nitzuk Chibur [See Admur 451:41 and Levush 93 who learns that the vapor prohibits due to the law of Nitzuk Chibur] or due to Mamashus [See P”M 92 M.Z. 29 and O.C. 441 A.A. 44 and Yad Yehuda 92:52 who learns that the prohibition of Zeiah is due to Mamashus falling back inside.] Thus, although some Poskim entertain that perhaps our ovens today do not have a Mamashus prohibition, as the vapor will not fall back down [Shut Beis Hayotzer], nevertheless, it would still be forbidden due to Nitzuk Chibur.

[250] 92:8

[251] Rama 92:8

[252] Rama ibid

[253] The reason: As when it is covered the vapor cannot escape and it is thus similar to two dry pots touching each other [of which we rule that they both remain Kosher, as without liquid in between taste cannot spread]. [Rama ibid]

[254] Issur Viheter 31:17; Toras Chatas 56:8; Kaf Hachaim 92:101

[255] As in such a case the dairy vapor becomes absorbed in the bottom of the meat pot, and what difference does it make if the meat pot is covered or not!

[256] Michaber and Rama 92:8; Tur 92 in name of Rosh Kalal 20:26

[257] Rama ibid

[258] Rama ibid “The [meat] food in the pot requires 60x versus the milk in the pan”; However, see Beis Yosef 92:8 in name of Rosh ibid that one needs 60 x 60 of the milk. Vetzaruch Iyun!

[259] The reason: As the vapor from the milk hits the bottom of the meat pot and penetrates into the food. [Michaber ibid] And the vapor of a food is considered like the actual food. [Michaber and Rama 92:8; 123:24; and so is proven from chapter 93 regarding the prohibition of the covers of a pot; Tur 92 in name of Rosh Kalal 20:26; Admur 442:9 “The vapor of Chametz is like actual Chametz”; Tzemach Tzedek O.C. 43; Rav Poalim 3:24 that this is Davar Pashut!] And even the vapor of vapor is considered like the actual food. [Chida in Maras Ayin p. 76; Maharsham 3:60; Rav Poalim ibid, unlike the lenient opinions] Now, this prohibition of Zeiah is either due to Nitzuk Chibur [See Admur 451:41 and Levush 93 who learns that the vapor prohibits due to the law of Nitzuk Chibur] or due to Mamashus [See P”M 92 M.Z. 29 and O.C. 441 A.A. 44 and Yad Yehuda 92:52 who learns that the prohibition of Zeiah is due to Mamashus falling back inside.] Thus, although some Poskim entertain that perhaps our ovens today do not have a Mamashus prohibition, as the vapor will not fall back down [Shut Beis Hayotzer], nevertheless, it would still be forbidden due to Nitzuk Chibur.

How to measure the 60x: One measures 60x versus the entire milk that is in the pot. However, there is no need to measure 60x versus the dairy pot, being that its absorbed taste is Nat Bar Nat Dihetera. However, if the pot contained Issur, then one must measure 60x versus the Issur and the absorbed Issur within the pot. [P”M 92 M.Z. 29; Zivcheiy Tzedek 92:74; Kaf Hachaim 92:97]

[260] P”M 92 M.Z. 29; Zivcheiy Tzedek 92:74; Kaf Hachaim 92:96

The reason: As this is similar to the case where a drop of milk fell on a pot within food level, explained in Halacha 5B. [Poskim ibid]

[261] Peri Toar 92:16; P”M 92 M.Z. 29; Degul Mirivava 92

The reason: As the vapor forbids the meat pot and then returns and forbids the dairy pot.

[262] Peri Haretz 2:14; Erech Hashulchan 92:14 [implies he agrees with Peri Haretz]; Implication of Michaber and Rama ibid and Toras Chatas 56:8 [Kaf Hachaim 92:93] The Kaf Hachaim ibid concludes that one who is lenient does not lose out.

[263] The reason: As the vapor has ability to absorb into a food, but not to absorb, extract and then return to the original food it was sent from. [Poskim ibid]

[264] Peri Toar ibid; Kaf Hachaim 92:93; See Halacha 5A and Michaber 92:6

[265] Rama 92:8; Terumos Hadeshen 2:103; Beis Yosef 92:8

[266] Beis Yosef 92:8; Gloss of Rav Akiva Eiger on 92:8 in name of Mahariy; Pesakim Ukesavim 103; Levush 92; Shut Bach Hachadashos 24; Minchas Yaakov 56:27; P”M 92 M.Z. 29; Erech Hashulchan 92:14; Zivcheiy Tzedek 92:75; Kaf Hachaim 92:97; See, however, Yad Avraham on 92:8 that it has a status of hot that falls on cold in which case we rule that only a Kelipa worth is forbidden.

In a case of doubt: If one is unsure whether the steam was Yad Soledes, and the meat pot was cold, everything remains permitted. [Shut Bach ibid; Erech Hashulchan ibid; Rav Akiva Eiger ibid; Poskim ibid]

[267] Issur Viheter 31:16; Kneses Hagedola 92:71-72; P”M 92 M.Z. 29; Zivcheiy Tzedek 92:78; Kaf Hachaim 92:102

[268] P”M 92 M.Z. 29

If the pots became wet with their own condensation: Some Poskim rule that if the pots became wet with their own condensation, nevertheless they remain permitted if they are touching. [P”M ibid based on Toras Chatas 8; See Tzemach Tzedek O.C. 43 for a lengthy discussion on the status of condensation of a pot and the implication is that he too is lenient.]

[269] The reason: As taste cannot transfer from the material of one pot to another [without moisture in between], and we do not suspect that milk and meat may have splashed into each other, as we are not Machzik Issur. Likewise, there is no issue of Reicha to be worried of. [Poskim ibid]

[270] Rama 108:1

[271] See 92:8 regarding a similar case of cooking milk under a meat pot that the Rama rules that only if the vapor that reaches the upper pot is Yad Soledes do we say it becomes forbidden and requires 60x the milk. If however the vapor is not Yad Soledes by the time it reaches the upper pot then everything remains Kosher. Regarding if neither food gives off vapor, such as they are both bread, one Issur and one Heter, then seemingly everything would be permitted. Likewise, if the Heter gives off vapor but not the Issur everything would be permitted. If, however, the Issur gives off vapor then the Heter is forbidden even if the Heter does not give off vapor.

[272] If only one food was covered: See Admur 447:10 and Michaber 108:1 that it suffices for even one of the foods to be covered, however, that is regarding Reicha. However, regarding Zeiah, so long as the vapor of one of the foods hits the other food, it is forbidden, and thus both foods must be covered. Accordingly, if either the meat or milk food is uncovered, then seemingly both foods are forbidden as it is similar to the case of Rama 92:8 where the uncovered milk pot prohibits the even covered meat pot, as the vapor travels towards it. Similarly here, the vapor travels from the meat to the covered milk, and prohibits the covered Heter. Furthermore, even the uncovered food becomes forbidden as perhaps the vapor of the uncovered travels to the covered food, becomes prohibited, and then returns back to the uncovered food and prohibits it. [See Peri Toar 92:16; P”M 92 M.Z. 29; Degul Mirivava 92 regarding that the dairy uncovered pot also becomes forbidden even if the meat pot was covered.] This especially applies according to Admur 451:41 [and Levush 93] who learns that the vapor prohibits due to the law of Nitzuk Chibur, and hence it is as if one poured meat onto a Ben Yomo dairy pot, in which the Rama 95:3 rules it is forbidden. [This is unlike the P”M ibid and O.C. 441 A.A. 44 and Yad Yehuda 92:52 who learns that the prohibition of Zeiah is due to Mamashus falling back inside.] Vetzaruch Iyun from Kaf Hachaim 108:32 who explains that the Zeiah case which prohibits is if both the Heter and Issur are uncovered.

[273] The reason: If the food is doubly wrapped it remains permitted even if the oven is dirty with residue as the vapor only becomes absorbed in the external covering, and the internal covering does not absorb from the external one, being there is no moisture in between, and is similar to two dry pots touching each other. [See Taz 92:29; 97:3]

[274] As if there is leftover meat/milk/Issur, it will release vapor and prohibit even the covered foods!

[275] Taz 92:29; 97:3; Kneses Hagedola 92:73; Peri Chadash 92:36; Minchas Yaakov 56:22; Lechem Hapanim 92:54; 97:1; Halacha Pesuka 97:1; Beis Lechem Yehuda 92:40; P”M 92 M.Z. 29; 97 M.Z. 1; Sheilas Yaavetz 103; Erech Hashulchan 92:15 that so is opinion of all Achronim; Chochmas Adam 50:2; Zivcheiy Tzedek 92:79; Kaf Hachaim 92:103; 97:29; See Admur 451:41 and 67; Tzemach Tzedek O.C. 43

[276] P”M 92 M.Z. 29

The reason: As if there is moisture in-between the two materials, it serves as a conduit to transfer taste and prohibit the food.

[277] The reason: As this is similar to two pots touching each other in which we rule that both pots are Kosher, even though both pots contain absorption of taste of the opposite food. [Taz ibid]

[278] Beis Lechem Yehuda ibid in answer of the question of Nekudos Hakesef 97 against Taz; Minchas Yaakov ibid; Tzemach Tzedek ibid; Poskim ibid; Kaf Hachaim ibid;

[279] Erech Hashulchan 92:15; Kaf Hachaim 92:103

[280] Admur 494:16

[281] The reason for this is because taste cannot leave a vessel without actual touch [of food or liquid], thus since the food is not actually touching the metal roofing therefore no Issur taste which it absorbed is able to dissipate into the Kosher food. [Shach 108:12]

[282] Shach 108:12 in name of Teshuvos Mamimanis

[283] To note that only in this case is it required for the ceiling of the oven to receive vapor from both foods as if the second food which is Heter does not give off vapor, such as if it is bread, then it is impossible for any taste to leave the ceiling and enter back into the food. However in the previous case that both were baked simultaneously, even if only the Issur gives off vapor it is forbidden.

[284] See Rama 92:7 that when the steam of the milk reaches the meat cover it removes the taste from the cover and travels it back down into the Heter.

[285] Vetzaruch Iyun what the law would be in a case that the Heter contained Charif, such as onions and the like.

[286] See Igros Moshe Y.D. 1:40; Maharsham 3:208; Minchas Yitzchak 5:20; Chelkas Yaakov 2:136; Kinyan Torah 1:24; Badei Hashulchan 92:166; Darkei Halacha p. 242

[287] Erech Hashulchan 92:15; Kaf Hachaim 92:103

[288] As if there is leftover meat/milk/Issur, it will release vapor and prohibit even the covered foods!

[289] Hakashrus 2:53-54

[290] See Admur 453:23-24; Darkei Teshuvah 121:60; Piskeiy Teshuvos 451:42

[291] Shevet Hakehasi 2:45; Sefer Hakashrus 2:54 as there is 60x water versus food, and the detergent makes it Pagum.

[292] Hakashrus 2:7-9

[293] As possibly the peeler has been washed with hot water with the meat or dairy dishes, and/or stayed in liquid for 24 hours.

[294] The reason: As people do not usually peel hot meat/dairy with a peeler, and even if they did some Poskim allow to follow Rov Tashmisho, hence in a case that one does not recall using the peeler for peeling hot meat/dairy one may certainly be lenient, especially after 24 hours.

[295] See Hakashrus 2:60-63

[296] See the section regarding “Glass vessels”

[297] See the section of Glass vessels.

[298] See Hakashrus 2:30-31

[299] The reason: This is done in order to avoid getting residue of one food on the opposite dish. Likewise, if one uses hot water, the vessels can become forbidden if there is residue of meat and milk there.

[300] If one allows the residue to soak for 24 hours with the vessels it becomes prohibited due to Kavush.

[301] See Chapter 8 Halacha 30E!

[302] See Hakashrus 1:13-19

[303] Minchas Yitzchak 2:100

The reason: This is due to several reasons: 1) As it is common to pour hot food into the sink, as well to use hot water to wash the dishes. Hence, if the sink would be used for both meat and dairy, the sink and possibly the dishes inside would become Treif. For example, if one pours hot water to wash the meat dishes and then poured hot water to wash the dairy dishes, some Poskim rule that the dairy dishes absorb from the Treif taste absorbed in the sink, and become forbidden. If the sink was not cleaned of meat residue, this is certainly a problem according to those Poskim. [See stringent Poskim in Chapter 8 Halacha 30D] 2) Another issue is regarding meat and dairy foods resting in the sink for 24 hours which would prohibit the sink due to the rule of Kavush, and likewise prohibit any vessels that soaked in it during that time. 3) All this is aside for the possibility of mistakes occurring, such as pouring a hot chicken soup into the sink while the dairy dishes are resting inside, thus prohibiting all the dishes.

[304] See in great length Igros Moshe Y.D. 2:42 for a defense of the custom to use the same sink for washing meat and then washing dairy dishes [separately] and a Halachic analysis on the power of pouring from a Keli Rishon. This response of Rav Moshe was to the prohibiting ruling of Rav Halbershtam who understood that base on the rule of Iruiy Keli Rishon, one may not wash dishes in the same sink; See Yabia Omer 5:33

[305] See Minchas Yitzchak 2:100; Igros Moshe Y.D. 2:42; Hakashrus ibid

[306] As if the hot Yad Soledes Iruiy Keli Rishon water touches the meat sink, it causes the sink to absorb the milk residue that is in the sink insert and prohibits the sink. This then cause issues with being allowed to use the meat sink for hot water washing. See Chapter 8 Halacha 30D! See however Igros Moshe ibid who is lenient in this matter.

[307] Technically, if hot water is not being used, there is no issue with having meat residue in the sink while washing the dairy dishes. However, since it is possible that residue will get stuck to the vessels and will go unnoticed in the cleaning, therefore one is to clean the sink beforehand. Likewise, if one leaves the vessels in the sink for 24 hours together with the meat residue, everything becomes forbidden unless the water contains 60x the residue.

[308] Since the sink is considered Treif due to its use for pouring hot meat and dairy into it, pouring even hot Pareve food onto the sink while dishes are there can cause the forbidden absorbed taste that is in the sink to become absorbed into the dishes. See Chapter 8 Halacha 30D!

[309] If one uses Yad Soledes water it can cause the forbidden absorbed taste that is in the sink to become absorbed into the dishes. See Chapter 8 Halacha 30D!

[310] This is due to the issue of Kavush Kimivushal, as since the sink is Treif due to the dual usages of hot pourings, therefore one may not initially soak food or vessels in it for 24 hours, even though Bedieved everything remains permitted as it is in any event not Ben Yomo by that time.

[311] See Hakashrus 1 footnote 26

[312] See Hakashrus 1:14 footnote 26 regarding a metal sink; Kashrus Bamitbach Hamoderni 6

[313] As by a metal sink, there is the added problem of spread of taste from one sink to the other even without heat on the other side. [See coming footnotes]

[314] The concerns: The concern is that meat/dairy taste will spread through the joint material into the adjacent sink and make it Treif. This can happen if a Keli Rishon hot food [such as a Davar Gush or Iruiy Keli Rishon hot food according to Taz 105:4 and Rashal] was placed into any material sink and caused the other sink to get heated up. Or [according to some Poskim] if a Keli Rishon hot food [or Iruiy Keli Rishon hot food according to Taz and Rashal] was placed into a metal sink, even if it did not cause it to get heated up.

[315] The reason: When hot Keli Rishon meat or milk spills into the sink it penetrates the wall a Kelipa worth and depending on the thickness of the shared wall, can penetrate to the other side of the wall. Furthermore, some Poskim rule Iruiy Keli Rishon can penetrate past a Kelipa and it can hence spread as far as its heat can travel, and by a thin wall, the heat could possibly travel to the other side. [Taz 105:4; Rashal and Perisha according to Rabbeinu Tam, brought in Shach 105:5]

[316] As some Poskim hold that by a metal vessel, taste can travel even to cold areas [See P”M 94 M”Z 1; Kaf Hachaim 94:13 and 18], and hence if a Keli Rishon food falls on the wall of one side [such as a Davar Gush], it can send its taste to the other side, even if it is cold. [1^st opinion in Admur 451:22 and 451:75; Michaber 121:7; Taz 121:7; M”A 451:24; Tur Y.D. 121; Rashba in Toras Habayis Hakatzar 4:4] Furthermore, according to those Poskim who rule that even Iruiy Keli Rishon sends taste past a Kelipa worth [Taz 105:4; Rashal and Perisha according to Rabbeinu Tam, brought in Shach 105:5] possibly, this would apply even if the other side is cold, if the material is made of metal. Accordingly, it is best to be stringent by metal sinks, although those who are lenient have upon whom to rely, which are on those Poskim who rule that taste does not travel without heat, and it is unlikely that by a thick wall the other side will become hot. [2^nd opinion in Admur 451:22; 1^st approach in M”A 441:24; Shach 94:3 and 28; 121:17; Teshuvah Maharam Mitz; Rashal Chulin 41; Peri Chadash 94:3 and 24; 121:15]

[317] The reason: If, in truth the walls are thick, and there is a Kelipa’s worth available for each side, then there is no real concern, as the food in a sink is never an actual Keli Rishon [which can penetrate even past a Kelipa worth] but rather an Iruiy Keli Rishon, which can only penetrate a Kelipa worth irrelevant of how far the heat travels. [Shach 98:13 in name of Toras Chatas Klal 85 in name of Issur Viheter; Shach 105:5] Hence, even if meat and dairy Keli Rishon spills on their perspective side of the shared wall, they remain Kosher, as the meat and dairy taste cannot penetrate more than a Kelipa. Now, although there are Poskim who rule that Iruiy Keli Rishon can penetrate more than a Kelipa worth [Taz 105:4; Rashal and Perisha according to Rabbeinu Tam, brought in Shach 105:5], and certainly by a Davar Gush many Poskim rule it always retains its status as a Keli Rishon, nevertheless, by a non-metal vessel the taste can only travel up until the areas that are Yad Soledes, and it is unlikely by a thick wall that the other side will become hot to the point of Yad Soledes.

[318] The reason: Taste of meat or dairy can only transfer from the meat side to the dairy side, or vice versa, if the material of the sink reaches a heat of Yad Soledes [by non-metal materials] and is the status of a Keli Rishon. Accordingly, an attached dual sink is permitted to be used for several reasons: a) As stated above, a sinks hottest usage is Iruiy Keli Rishon and almost never Keli Rishon, it hence will never travel more than a Kelipa’s distance, irrelevant of how far the heat travels. [Shach 98:13 in name of Toras Chatas Klal 85 in name of Issur Viheter; Shach 105:5] Accordingly, since the hot meat and milk will be spilled only into their respective sinks, it will not spread into the adjacent sink, even if the adjacent sink somehow became hot due to it. B) Even if the usage is Keli Rishon, which can travel more than a Kelipa, and even if we would rule like the Poskim who rule that Iruiy Keli Rishon can penetrate more than a Kelipa worth [Taz 105:4; Rashal and Perisha according to Rabbeinu Tam, brought in Shach 105:5], it is still not an issue by non-metal sinks, as by non-metal material, taste can only travel with heat, and since the hot meat/milk in one sink will never be hot enough to heat up the opposite sink, taste of meat/milk will never travel between them. It is highly unlikely that the attached part of the sinks will ever reach Yad Soledes due to hot meat or milk of the other side, and certainly it would not make the actual meat or dairy sink hot enough to travel its taste to it. If, however, in truth the food would heat up the opposite sink, then even by non-metal materials it could spread its taste to the hot areas. [P”M 94 M”Z 1; Kaf Hachaim 94:13 and 18]

[319] Even if the sink is made of metal with a usage of a Keli Rishon, the main ruling is that we do not say Cham Miktzaso Cham Kulo even by metal [1^st opinion in Michaber 94:1; Rama 94:1], and many Poskim rule this applies even regarding absorbing taste and not just regarding expelling the taste [2^nd opinion in Admur 451:22; 1^st approach in M”A 441:24; Shach 94:3 and 28; 121:17; Teshuvah Maharam Mitz; Rashal Chulin 41; Peri Chadash 94:3 and 24; 121:15]. However, according to those Poskim who rule that even those who do not hold of the rule of Cham Miktzaso Cham Kulo, it does absorb fully into metal even when cold [1^st opinion in Admur 451:22 and 451:75; Michaber 121:7; Taz 121:7; M”A 451:24; Tur Y.D. 121; Rashba in Toras Habayis Hakatzar 4:4], then in truth taste could spread from one side to another, and according to those Poskim who rule Iruiy Keli Rishon spreads even past a Kelipa [Taz 105:4; Rashal and Perisha according to Rabbeinu Tam, brought in Shach 105:5], this would apply even if one pours hot metal or milk into his sink. Accordingly, it is best to be stringent by metal. However, those who are lenient certainly have upon whom to rely as a) It is highly unlikely that one sink will become hot due to the heat in another sink and b) We do not use actual Keli Rishon in a sink and hence even according to the opinion who holds that metal can spread taste even by cold, would not hold this to be the case regarding Iruiy Keli Rishon as the main opinion follows that Iruiy Keli Rishon does not spread more than a Kelipa.

[320] See Hakashrus 2:55-59

[321] Rama 88:2; Taz 95:19 in name of Rashal; Kneses Hagedola 88:8; Kisei Eliyahu 88:5; Birkeiy Yosef 88 Shiyurei Bracha 9; Zivcheiy Tzedek 88:25; See Kaf Hachaim 88:29-33

[322] Igros Moshe Yoreh Deah 1:38; Rivivos Ephraim 5:514

[323] The reason: being that at times one dips the shaker into the food, and at times hot vapor from the food enters the shaker. This especially applies in a home with children. It is understood that if one sees that the salt made contact with the meat or dairy food that it may not be used with the opposite food unless it is cleaned in-between.

[324] See Hakashrus 2:21; Kashrut Veshabbat Bamitbach Hamoderni [Printed by Hamachon Letechnalogy Lehalacha in Yerushalayim] pp. 29-105; Hakashrus Kehalacha p. 172; 340

[325] The reason: As steam is considered a form of cooking and turns the pot into a Keli Rishon just like a fire. [See Shut Maharsha 1:92; Sdei Chemed 5:24; Darkei Teshuvah 121:16; Igros Moshe Y.D .60; Seridei Eish 2:35] Now, the pot which contains meat food sends meat taste throughout the pillar of steam, and turns the boiler, as well as the steam/water, to a meat status. If this water/steam is then used to cook dairy, it is as if one took the gravy of a chicken soup and entered it into milk.

[326] See Hakashrus 1:20-30

[327] The potential complications: See the conditions listed below of which a lack of adherence to those conditions can prohibit the pot and its contents.

[328] See Erech Hashulchan 92:15 and Kaf Hachaim 92:103 that it is proper to initially avoid cooking dairy on a meat surface even if the surface area is dry and clean, if the matter is not necessary; Chochmas Adam 74:4; Kesav Sofer Y.D. 54; Teshuvos Vehanhagos 2:387; Hakashrus 1:20

[329] See Rama 93:1; Admur 451:41 and 67; Taz 92:29; 97:3; Kneses Hagedola 92:73; Peri Chadash 92:36; Minchas Yaakov 56:22; Lechem Hapanim 92:54; 97:1; Halacha Pesuka 97:1; Beis Lechem Yehuda 92:40; P”M 92 M.Z. 29; 97 M.Z. 1; Sheilas Yaavetz 1:103 and 113; Erech Hashulchan 92:15 that so is opinion of all Achronim; Chavos Daas 92; Chochmas Adam 45:19 and 50:2; Zivcheiy Tzedek 92:79; M”B 451:34; Kaf Hachaim 92:103; 97:29; See Tzemach Tzedek O.C. 43; Hakashrus 1:20; Pischeiy Halacha 1:30; Igros Moshe Yoreh Deah 1:40 and 2:59

The reason: a) We do not suspect that milk and meat may have splashed onto the grate, as we are not Machzik Issur. b) Even if it did splash, taste cannot transfer between two materials unless there is heat and moisture in-between. Thus if one abides by the conditions which verify cleanliness and dryness when placing the pot on the grates, there is no issue with the fact that one is cooking dairy on grates that are Treif or meaty. [Poskim ibid]

[330] See Igros Moshe Y.D. 2:59 who allows using the same grates and does not mention any conditions, as he assumes as writes the M”B ibid that we don’t suspect for spillage, and even if spillage occurred it gets burnt, and the grate gets Koshered through the fire. Vetzaruch Iyun as the M”B statement was said regarding the grates of previous times, in which the coals completely surrounded the grates, however, today the fire does not reach all areas and hence certainly must be cleaned and dry.

[331] See Beis David O.C. Pesach 208; Zechor Leavraham Y.D. 2; Zivcheiy Tzedek 87:48; Kaf Hachaim 87:65

[332] See M”B ibid that we can assume that the fire has burnt off all the residue. This was said regarding the grates of previous times, in which the coals completely surrounded the grates. However, by today’s gas stoves, this is not the case. Vetzaruch Iyun from Igros Moshe Y.D. 2:59 who extends the allowance even to today’s stoves!

[333] The reason: As if they are wet, the forbidden taste that is absorbed within the grates can enter the food.

[334] See Beis David O.C. Pesach 208; Zechor Leavraham Y.D. 2; Zivcheiy Tzedek 87:48; Kaf Hachaim 87:65; Chapter 8 Halacha 18!

[335] See Hakashrus 1 footnote 51

[336] See Shach 92:32; Kneses Hagedola 92:85; Peri Chadash 92:29; Lechem Hapanim 92:47; Beis Lechem Yehuda 92:35; Minchas Yaakov 56:20; Kreisi 92:26; P”M 92 S.D. 32, M.Z. 25; Biur Hagr”a 92:35; Chochmas Adam 45:14; Zivcheiy Tzedek 92:55; Kaf Hachaim 92:80

[337] The reason: As Ein Machzikin Issura, and hence if one did not see any spillage we do not assume that it occurred. [See Chochmas Adam 45:15; Zivcheiy Tzedek 92:60; Kaf Hachaim 92:84]

[338] See Rama 95:3 regarding pouring from a Ben Yomo meat pot to Ben Yomo dairy pot. Vetzaruch Iyun if the Michaber ibid who is lenient in that case would be lenient here as well

[339] See Hakashrus 1:26-27

[340] See Rama 92:8; Admur 451:65-67; Erech Hashulchan 92:15; Kaf Hachaim 92:103

[341] P”M 92 M.Z. 29

[342] The reason: As taste cannot transfer from the material of one pot to another [without moisture in between], and we do not suspect that milk and meat may have splashed into each other, as we are not Machzik Issur. Likewise, there is no issue of Reicha to be worried of. [Poskim ibid]

[343] If the area that the food fell on contains hot residue or is Ben Yomo, then it requires 60x versus the residue. If the residue is cold but the food is hot, then only a Kelipa is required. See next footnote for sources.

[344] See Chapter 8 Halacha 18 regarding if the stove top was clean and Chapter 8 Halacha 11 regarding if it was dirty.

[345] Admur 451:13 in gloss; 1^st approach in Shach 121:7; unlike 2^nd approach in Shach ibid based on ruling of Ramaz 96 that requires Libun Chamur even by Basar Bechalav.

Earthenware: Regarding earthenware [and all other non-Kosherable materials], Libun Gamur is required even by Basar Bechalav that became absorbed one after the other. [See Admur 494:16; and 461:1; 451:7 regarding Chametz]

[346] Admur 451:24 regarding grates that absorbed Chametz; 451:13 that this applies even by Basar Bechalav if it absorbed the prohibited mixture; Rav Wozner in Kuntres Mibeis Levi 1:29 regarding Chametz

Other opinions: Some Poskim rule that grates only require Libun Kal. [M”B 451:34; Igros Moshe 1:124; Piskeiy Teshuvos ibid]

[347] Hakashrus 1:29

[348] See Hakashrus 1:30

[349] If the vapor hits the vessel or food while Yad Soledes, then its taste penetrates the vessel and food and can prohibit an opposite form of vessel, and turn Pareve foods into meaty or dairy. If, however, the vapor is not Yad Soledes by the time it hits the vessels or food, then everything remains its status, although the vessels are to be washed prior to use in order to wipe away any less than Yad Soledes vapor that reached it. See our corresponding Sefer “A Semicha Aid for the Laws of Basar Bechalav” Chapter 92 Halacha 9A

[350] The potential complications: See the conditions listed below of which a lack of adherence to those conditions can prohibit the pot and its contents.

[351] The red-hot heating of the element is equivalent to Libun Gamur, and hence the coil is officially considered as if it were Koshered. There is thus no need to worry of placing a wet pot onto the coil. Likewise, any food residue that is on the coil becomes burnt off upon turning it on.

[352] Although the actual coil area of the ceramic stove is fully Kosherable by simply turning it on [i.e. Libun Gamur], nonetheless the surrounding areas that do not become red hot, are not Kosherable. At times the circumference of the pot is larger than that of the red coil, and hence ends up touching the non-Kosher area. In addition, at times the coil itself does not become fully red and contains unheated pockets.

[353] See Rama 93:1; Admur 451:41 and 67; Taz 92:29; 97:3; Kneses Hagedola 92:73; Peri Chadash 92:36; Minchas Yaakov 56:22; Lechem Hapanim 92:54; 97:1; Halacha Pesuka 97:1; Beis Lechem Yehuda 92:40; P”M 92 M.Z. 29; 97 M.Z. 1; Sheilas Yaavetz 1:103 and 113; Erech Hashulchan 92:15 that so is opinion of all Achronim; Chavos Daas 92; Chochmas Adam 45:19 and 50:2; Zivcheiy Tzedek 92:79; M”B 451:34; Kaf Hachaim 92:103; 97:29; See Tzemach Tzedek O.C. 43; Hakashrus 1:20; Pischeiy Halacha 1:30; Igros Moshe Yoreh Deah 1:40 and 59

The reason: As taste cannot transfer between two materials unless there is heat and moisture in-between. [Poskim ibid]

[354] See Beis David O.C. Pesach 208; Zechor Leavraham Y.D. 2; Zivcheiy Tzedek 87:48; Kaf Hachaim 87:65

[355] The reason: As if they are wet, the forbidden taste that is absorbed within the grates can enter the food.

[356] See the section on “Glass vessels” for all the opinions on this matter!

[357] The reason: As in addition to the fact that many Poskim hold glass is unobservant, some Poskim rule that moisture between two Ben Yomo vessels does not prohibit the vessel [see Michaber 95:3] thus seemingly there is greater room for even Ashkenazim to be lenient in this case.

[358] Michaber 89:4; Teshuvas Ramban 172; Hakashrus 2:50-54

[359] Michaber ibid

The reason: As we suspect that perhaps some meat or cheese has remained stuck to the tablecloth and will now enter one’s food. [Yad Avraham 89]

[360] Rama 89:4

[361] As it is common for food and oily substances to get stuck on tablecloths and get overlooked.

[362] See Kitzur SHU”A 42:2

[363] Yad Avraham 89 that so is evident from the ruling that two people may eat milk and meat on the same table if there is a reminder between them; Darkei Teshuvah 89:48; See M”A 173:1 in name of Bach 173

[364] Radbaz 2:721; Pischeiy Teshuvah 89:8; Kaf Hachaim 89:67

[365] Radbaz ibid; Pischeiy Teshuvah ibid; Hakashrus 10:20

[366] Admur 453:23-24; Darkei Teshuvah 121:60; Piskeiy Teshuvos 451:42

[367] Shevet Hakehasi 2:45; Sefer Hakashrus 2:54 as there is 60x water versus food, and the detergent makes it Pagum.

[368] Hakashrus 2:47-48

[369] As some Poskim rule a Keli Sheiyni can absorb, as well as that the milk may remain there for 24 hours and become Kavush. This is in addition to the fact that thermoses are difficult to clean, and hence even according to the Poskim who are lenient regarding glass, would agree here that one must be stringent. [See Hakashrus ibid]

[370] Hakashrus 1:51-54

[371] This applies even after 24 hours, as toasters are very difficult to clean and may contain dairy residue.

[372] See Hakashrus 2:49

[373] The reason: As it is common to place food directly on the tray, and it is thus similar to the law regarding tablecloths, that one is to have separate tablecloths for dairy and meat. [Michaber 89:4]

[374] See Hakashrus 1:28

[375] See Hakashrus 1:68-70

[376] See Shulchan Gavoa 1; Kaf Hachaim 95:4

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