Chapter 257

Chapter 257

The Laws of insulating hot foods


In the previous chapters the laws relevant to leaving food on a flame from before Shabbos and placing it there on Shabbos were discussed. In the following chapter the laws of insulating a food before Shabbos and on Shabbos will be discussed.  Here too the Sages gave certain restrictions as to how one is allowed to insulate from before Shabbos, and on Shabbos.


Insulating food before Shabbos

Halacha 1

Not to insulate with materials that increase heat: One which desires to remove a pot from on top of a Kirah and insulate it in order so it not become cold, it is forbidden for him to insulate it in a material which increases heat, even if one wants to do so from before Shabbos.

The reason for this restriction is because: it is a decree made due to that [if this were to be permitted] then one may come to insulate the pot in ember, which is ashes which has coals mixed into it[1], and then afterwards on Shabbos one [may] forget and stoke the coals.

If one transgressed and insulated in material which adds heat: If one transgressed and insulated [in material which increases heat], [then] even [if this was done] inadvertently [without prior knowledge of the prohibition], [nevertheless] the food is forbidden both to him and to others until after Shabbos.[2] [However this only applies] in a case that the added heat to the food made it condense in a way beneficial to it, or if the food was cold and got heated through this insulation. However if it remained the same temperature as it was originally, and it’s a food [which has been cooked to the point] that further cooking will cause it to condense in a way detrimental to it, then it is permitted [to be eaten on Shabbos], being that there is no benefit being gained from having done the prohibition[3].

May one insulate with a heating material food which further cooking will cause damage? Nevertheless initially it is forbidden to [insulate with material that increases heat] even if further cooking of this food causes it to condense in a way that is detrimental to it[4].

The reason for why it is allowed to leave half cooked food over a fire from before Shabbos, but is not allowed to insulate a food with a material that increases heat: [The above scenario of insulation] is not similar to leaving a pot on a flame over Shabbos, which is permitted to be done when left on top of a Kirah that is not swept or covered as long as the food has been cooked to the point of the food of Ben Drusaiy from before Shabbos, as usually insulation is done for the need of [food which will be eaten] the next day. As one insulates the food and covers it so it not cool down by the next day. Therefore it is more required to be stoked [than food left on a flame], in order so the food not cool off over the entire night. However by leaving food on a flame, usually this is done for the [food to be eaten by the] night meal, as one leaves the pot there without insulation[5], it therefore does not need that much to be stoked  if the food has already cooked to the point of the food of Ben Drusaiy from before Shabbos. [Furthermore] even if one were to leave this food [on the flame until] tomorrow, there is [still] no suspicion that one will come to stoke the coals, as the little bit of stoking that can be done will not be of help for it to stay hot until the next day being that the pot is not insulated. However when the pot is insulated, a little bit of stoking can help [it retain heat until the next day] and therefore we are worried that one may come to stoke the coals if the pot is insulated in ember. [Now although the above suspicion only applies to ember, being that it can be stoked, as opposed to other materials which add heat, nevertheless] the [Sages] decreed [against using] any material that increases heat because of [the suspicion involved with] ember. [Furthermore this prohibition applies] even if one insulates [the pot] for the need of the night [meal], being that the Sages did not make any differentiations in their decree[6].


Insulating completely raw meat right before Shabbos begins: Based on the above reason it is forbidden to insulate even completely raw meat close to Shabbos. As although it is allowed to leave raw meat [over a fire] being that one will [anyways] not think about it until the next day, [and there is thus no suspicion that one may come to stoke the coals at night, and even the next day there is no suspicion] as the meat is able to [become fully] cooked throughout the entire night without stoking, and [even if] the meat will be able to cool off afterwards[7] [nevertheless there is no worry that one may come to stoke the coals to prevent this as] a little stoking will anyways not be effective [to keep it warm for the next day] since the meat is not insulated. However when the meat is insulated, we are worried that perhaps one will stoke it after it is cooked in order to retain its heat, so that it not cool down, and for such a purpose [even]  a little bit of stoking is effective.

Other Opinions:  [However] there are opinions which argue on this and say that even to insulate from before Shabbos in materials which add heat is permitted as long as the food has cooked to the point of the food of Ben Drusaiy [from before Shabbos] or if [the meat] is completely raw literally right before Shabbos, just as it is permitted to leave it on a Kirah which is not swept or covered, as explained in chapter 253.


The Final Ruling: In a community that it is the custom to be lenient like this [latter] opinion, one should not protest against them doing so.  However this custom should not be followed in other places. 

More lenient opinions: There are those which are even furthermore lenient that even if the food is not completely raw close to Shabbos, nevertheless, if one removes his mind from it until the next day [meaning he does not plan to eat it until Shabbos day], it is considered as if it is completely raw, and is thus permitted to insulate it [even with material that add heat] for the use of the next day. This applies even though it has not yet reached the point of Ben Drusaiy [from before Shabbos].


The Final Ruling[8]: One may not [initially] rely on this opinion, unless it is already after the fact[9] [in which case one may rely on them] as long as this does not occur on a regular basis.


Insulating food on Shabbos

Halacha 2

Insulating food on Shabbos itself: On Shabbos itself it is forbidden to insulate the hot foods even with material that does not add heat.

The reason: [Now,] although [insulating with material that does not increase heat] is not similar to [insulating with] ember at all, and thus why then is it forbidden? [Nevertheless it is forbidden] due to a decree that perhaps when one comes to remove the pot from the stove, in order to insulate it with material that does not increase heat, he will find that the pot is cold, and he will forget that it is Shabbos and will reheat it on the fire and come to be liable for [the prohibition of] cooking. [Now this suspicion only applies according to those which hold that reheating a cooked food constitutes cooking, however] according to those which say that there is no cooking [prohibition involved] with [reheating] something that was already cooked even if it became cold afterwards, as will be explained in chapter 318, [nevertheless even according to them insulating on Shabbos is forbidden due to a different worry as] we are worried that one may stoke the coals in order reheat it and will thus be liable for [the prohibition] of lighting a fire.

Is it permitted to insulate by Bein Hashmashos[10] on Erev Shabbos?  However by Bein Hashmashos, even though it is questionable if it is considered nighttime [and thus perhaps Shabbos has already begun, nevertheless], one is permitted to insulate [food] in something that does not add heat. [However if the insulation adds heat it is forbidden to insulate with it starting from after sunset.]


The reason for why this is permitted is: because pots are usually still hot by Bein Hashmashos, as close to Bein Hashmashos the pots are removed from the fire and thus [at Bein Hashmashos] there is no need to worry that perhaps the food has cooled off and one will come to reheat it.

Halacha 3

May one insulate on Shabbos food which further cooking will cause it damage: Even food which is completely coked and further cooking will condense it in a way that is damaging to it, is forbidden to be insulated from when it becomes dark [after Bein Hashmashos, by the definitive beginning of Shabbos], even with a material that does not add heat.

Halacha 4

Placing an upside down pot over a hot pot on Shabbos: It is forbidden to place a vessel as a covering over a  hot pot for the purpose of retaining its heat (if the pot is entirely insulated underneath the vessel[11]), unless the vessel is wide enough to the point that its walls do not touch the sides of the pot[12], in which case there is no [prohibition of] insulation being done at all.

Covering the pot in order to guard it: However it is permitted to place a vessel on top of food in order to guard it from mice, or so that it not get dirty from the ashes, as this is not considered insulating for retaining of heat, but is rather is a measure of guarding and [is like] placing a cover on top of a pot.


Different details relevant to insulating on and before Shabbos

Halacha 5       

Which materials are considered to add heat?

The following materials always add heat even when dry: The following are materials which add heat [whether they are wet or dry]: Waste of olives and of sesame seeds [that is left] after their oil has been removed, and fertilizer and salt and lime and sand, whether they are wet or dry [they add heat].

The following add heat only when they are wet: Straw and sediment, which is grape waste [that is left] after their wine have been removed, and Mochin, (which is a general term for any soft material such as cotton and strings [made] of soft wool of an animal, and the scrapes of worn out clothing) and herbs, when these four materials are moist[13] [they add heat], even if they are wet with cold water which fell onto them.

The following materials do not add heat:  However all types of garments and fruits and feathers of all birds and thin residue of flax[14] and sawdust of carpenters, and skins whether they have been processed or not processed, and the fleece of wool[15] do not add heat in any situation.

Halacha 6

Insulating with ash: Ash which does not have coals mixed into them, even if it is hot, do not add heat.

If one insulated in this ash a pot from before Shabbos, and on Shabbos one found mixed in it a few fiery coals surrounding [the pot] or underneath it, then [nevertheless] the food is not forbidden after the fact, being that the insulation was done with a permissible material.

Halacha 7

Insulating with stones: It is permitted to insulate with stones from before Shabbos even though they add heat, as it is extremely uncommon to insulate with stones, being that they break the pot, or they ruin the food, and anything that is not common the sages did not decree against. However something that at times is used to insulate in, even though it is not so common, [nevertheless] the Sages decreed not to insulate in it if it adds heat. 

Halacha 8

May one re-insulate on Shabbos a pot that had been insulated before Shabbos?

If one insulated [a pot] from before Shabbos with a material that does not add heat, and it unraveled before Shabbos, whether it unraveled on its own, or if one unraveled it with his hands and one had in mind to go back and re-insulate it before Shabbos or after Shabbos has begun, it is forbidden to re-insulate it once Shabbos has begun [past Bein Hashmashos], as this is considered like one is initially insulating [the pot] on Shabbos [which is forbidden to do], since when Shabbos came in it was not insulated.

However if it was insulated[16] in the beginning of the entrance of (Shabbos[17]) the night, and then afterwards it unraveled, it is permitted to go back and insulate it. This applies whether it unraveled on its own or if one did so with his hands, even if [at the time that he unraveled it] he did not have in mind to go back and insulate it[18]. [Furthermore] even initially one may unravel it and then return and insulate it. 

Similarly if one wants to add [to the insulating material] on Shabbos other materials which do not add heat, he may do so. As well if one wants to remove all of the insulating material [placed before Shabbos] and place other material there in its place, whether the original insulation is hotter than the second one, or if the second insulation is hotter than the first [he may do so]. Even if the pot was only insulated with a sheet, one can remove the sheet and insulate it with a thick blanket.

[However] this only applies if the food was fully cooked, however if it is not fully cooked and is insulated on top of a Kirah (that has in it coals) in the [permitted] ways to be explained [in Halacha 10], then it is forbidden to even add on to the cover, as this addition causes to speed up the cooking due to the coals. 


Halacha 9

Insulating on Shabbos food which has been transferred to a different pot:

It was only made forbidden to insulate on Shabbos with material that does not add heat, when one is insulating the actual pot in which the food was cooked in, as then the decree that one may come to heat it up is applicable. However if one removed the food into another pot, it is permitted to insulate it.

[Furthermore] even if one goes back and returns the food into the original pot, it is permitted  to insulate it (being that the food has already cooled off a little in the walls of the second pot, and the Sages only forbade insulating if the food is [still] hot in the original pot that it was cooked in.)

Insulating cold food on Shabbos: ([Furthermore] if the food cooled off to the point that it is not Yad Soledes, it is permitted to insulate it even while it is still in the original pot.[19]) and certainly it is permitted to insulate completely cold food in order so it not become too cold, or in order to remove its coldness [see note][20]

The above is allowed only with materials that do not add heat: However all the above is only [allowed] when using insulation material that does not add heat, however material which adds heat, is forbidden to insulate with, even completely cold food, and even before Shabbos.


Halacha 10

Insulating before Shabbos with non-heat adding material however on top of material that adds heat:

A box which had a pot insulated inside it with Mochin or other materials which do not add heat, it is forbidden to place it from before Shabbos on top of olive waste. [The reason for this is] as they elevate the heat above them into the Mochin, and the Mochin then add heat into the pot which is insulated within it, and thus it is just like insulating with material that adds heat.

On top of Sesame waste: However it is permitted to place it on sesame seed waste, as they do not elevate the heat above them.

On top of a Kirah: Similarly it is permitted to place it into the Kirah that it was cooked in and insulate it there with material that does not add heat.

Now, although the surface of the Kirah which the pot is standing on is very hot, nevertheless, since the heat of the Kirah is not from it itself, but from the fire [that is in it], and [thus] as time passes it gets colder and colder, [therefore] it is not considered something that adds heat, and is not similar to olive waste and the like of which add heat from their own very substance.


A Kirah is only allowed if it has been swept of coals: Nevertheless [in order to be allowed to do this], the Kirah must be swept of its coals. However if there are coals in it, then even if they have dimmed, it is [nevertheless] forbidden to insulate in it a pot with clothing, or the like which do not add heat, even if it does not touch the coals at all, such as if it is sitting on a metal grid, or is sitting on top of stones.

The reason for this restriction is because: even though the clothing do not add heat due to themselves, nevertheless, due to the coals underneath them which elevate the heat, the clothes [do] add heat to the pot, and the pot is thus [considered] insulated in a material that adds heat.

The law if the insulation does not touch the walls of the pot[21]: If the [pot was insulated] in a way that the clothing are not touching the pot, such as if one placed over the pot of food a wider pot which [is wide enough that it] does not touch the sides of the [lower] pot and one then placed the clothing on the [external] pot, in which case it ends up that there is no insulation involved here at all, not even with a material that does not add heat[22], and it is thus permitted to be done. As even though the coals elevate heat above them, this is [Halachicly] meaningless being that the pot is not insulated in anything [and thus since it is not insulated, it does not fall under any insulation prohibition].[23]

Does the above leniency apply even if one places the pot directly on the coals: [The above leniency to allow placing a non-insulated pot into the oven only applies] when the pot is not touching the coals, [such as when it is sitting on an iron chair or on stones which are inside the oven]. However if its sitting on the coals, then even if the pot is completely uncovered [meaning there is not even a pot sitting over it], there are opinions[24] which prohibit this.

Their reason for this prohibition is:  because this is considered like one is insulating with a matter which increases heat, as [here] even the pot is touching the coals, and the coals elevate and add heat into the pot.

Other Opinions: [However] there are opinions which say that as long as the pot is not insulated by its top part it is not [Halachicly] considered insulation, and even if the pot is inside the oven and the opening of the oven above has been covered, [nevertheless] this carries no [Halachic] meaning.

Their reasoning is: because the Sages only prohibited insulating with material that adds heat because of a decree that [if this were to be allowed then] one may come to insulate in embers, therefore [insulating] is not prohibited unless it is done in a way similar [to insulating with] embers, [meaning that just like embers] is moveable and is attached to the walls of the pot [so too all insulation is only prohibited if it is moveable and attached to the walls of the pot]. [Thus being that] the walls of the oven and its opening are not attached to the pot [therefore it is not prohibited to be done]. ([This applies] even if the oven is small and narrow, as it is not possible that there isn’t a little bit of air separating the [walls of the oven from the pot])

The Final Ruling: The custom is like the latter opinion.

Halacha 11

The Shehiyah restrictions which apply when placing the pot directly on the coals: All the [discussion in the previous Halacha of placing a pot directly on the coals] only is relevant if the coals are covered or when the food has been cooked to the point of the food of Ben Drusaiy from before Shabbos, or when one placed a piece of raw meat in a pot literally very close to Shabbos, as if none of the above has been done then according to all opinions it is forbidden [to place the pot in the oven], even if there is no insulation involved at all, as was already explained in chapter 253 [under the laws of Shehiyah].

Do the Shehiyah restrictions apply when placing raw dough and legumes in the oven right before Shabbos? With regards to types of dough and types of legumes which cook quickly, it does not help at all if they are raw close to Shabbos,  (being that they are quick to cook) as was explained in chapter 254 [Halacha 6 and 13].

Halacha 12

The laws of Hatmanah in a case that the oven has been sealed shut with plaster: If the oven is plastered with clay around its covering, then it is permitted [to leave in it] in any scenario, even [if the food is] actually insulated (inside the coals). As [when the oven is sealed] there is no suspicion that one may come to  stoke [the coals], as explained [in chapter 254 Halacha 1]. Therefore it is the custom to seal the opening of the oven with clay. In places that this is not the custom, [they] must verify that there is no [prohibition of] insulation [involved], as well as [in order to also avoid the prohibition of Shehiyah] they need to cook the legumes and types of dough from before Shabbos to the point of the food of least Ben Drusaiy, or [alternatively they can make sure] that the coals be covered. 

Halacha 13

It is a Mitzvah to insulate food on Erev Shabbos so one can eat hot food on Shabbos: It’s a Mitzvah to insulate food for Shabbos in order so one can eat hot food on Shabbos, as [eating hot food] is [part of the mitzvah] of honoring and having enjoyment on Shabbos.

The law by one who hot food is unhealthy for him: However one who eating hot food causes him damage, it is permitted for him to eat [only] cold foods. However one who does not believe in the words of the Sages and prohibits eating hot food on Shabbos, we suspect that perhaps he is a heretic[25].


[1] Embers are the glowing, hot coals made of greatly heated [2] One should immediately remove the food from the insulation. [Shabbos Kehalacha Vol. 2 page 7]

[3] This is the opinion of the Michaber. However see below that we rule that if the food had been cooked to the point of Ben Drusaiy from before Shabbos then we are lenient to allow it to be eaten on Shabbos.

[4] The reason for this is explained in the Mahadurah Basra to be that a person would rather have his food be hot and condensed even in a damaging way, then to be not condensed but cold, and thus the same suspicion applies here too.

[5] Back then, before gas ovens, fuel had to be constantly added by hand in order for the flame to continue. Thus being that on Shabbos no more fuel may be added, one is only left with whatever amount of fuel was placed before Shabbos. Thus food which is needed for the next day’s meal will usually be insulated, as otherwise, even if left on the fire from before Shabbos it will become cold by the next day. However food needed for the night meal will retain heat without needing insulation. Thus the Alter Rebbe is explaining that being that the laws of Shehiyah only refer to leaving a non-insulated food on top of the fire, therefore it can be assumed that the food is needed for the night meal.

[6] Meaning that although based on the above explanation the suspicion only applies when one insulates with ember food to be eaten the next day, nevertheless insulating for the night is also prohibited, as once the sages decreed against insulation with materials that add heat, they made the decree inclusive to all scenarios, even those which technically do not have reason to be decreed against.

[7] Meaning even though that after it has fully cooked throughout the night, since it may cool down by the time the day meal arrives, there is thus room to suspect that one will come to stoke the coals so the food stay warm. Thus the Alter Rebbe explains that we do not suspect for this being that stoking will not help at all in this regard if the meat is not insulated.

[8] Regarding if this ruling includes also the previous mentioned cases of if the food was completely raw and the like, see Q&A 4 and the footnotes there.

[9] Meaning that if he has already insulated food for Shabbos day in material which adds heat, then one may be lenient to eat this food on Shabbos. To note that according to the Michaber all the above is forbidden even after the fact.

[10] Bein Hashmashos, in accordance to the final ruling and custom, is the time between sunset and the definitive beginning of night. The time of night definitively begins when one can begin to see three medium stars. Before these stars can be seen, it is questionable whether the in between time period is considered part of night or part of the previous day.

[11] Meaning that the vessel completely covers the pot, both on its top and its sides, as is the case when one places a large pot over a smaller pot that the smaller pot fits entirely into the large pot.

[12] Meaning there is space between the walls of the smaller pot and the walls of the large pot which is sitting over it.

[13] The Mishneh Berurah however learns that only if the following materials are wet from their own moisture do they add heat. However if they simply get wet, then they do not add heat.

[14] When flax is pressed there are small pieces of residue which fall from it.

[15] This refers to the entire sheet of wool as it is when it is first cut from the animal, before pieces of it are broken off to process. [see Rashi Shabbos 48a]

[16] Based on the definition of insulation for material that does not add heat. A pot is only considered to have been insulated from before Shabbos if its cover was insulated, whether or not its sides were insulated.

[17] The question here is regarding Bein Hashmashos. Meaning if the insulation unraveled by Bein Hashmashos what law do we give it. Seemingly this is the novelty in the additional words “Shabbos” that the Alter Rebbe is saying that once Shabbos has begun, which is after sunset, then if it was insulated and unraveled one may reinsulate it on Shabbos. 

[18] Seemingly this includes even if one specifically had in mind to not reinsulate it, and then changed his mind, that he is allowed to do it. So rules the Aruch Hashulchan and is implied from the Tehila Lidavid. [Shabbos Kehalacha vol. 2 page 63-64

[19] The Mishneh Berurah however and others rule that one should only be lenient to insulate food which is still hot but not Yad Soledes, within the original pot, if it is a pressing situation. Rav Farkash rules likewise being that even the Alter Rebbe placed this ruling of the Magen Avraham in parentheses. [Shabbos Kehalacha Vol. 2 page 53

[20] However if the material adds heat to the food, even if it is not defined as a material that adds heat, it is forbidden. [Shabbos Kehalacha Vol. 2 page 54-55]

[21] See also Chapter 253 Halacha 10 where this subject was already discussed in somewhat greater length, and gives more light onto the subject and the two opinions which are repeated in the Halacha here.

[22] Meaning that this type of insulation is not even considered a minor form of insulation, which is insulation with material that does not add heat.

[23] Thus one may as well place a wide board or metal over the top of the pot and then cover it with clothing, as the clothing do not touch the side of the pot.

[24] Michaber

[25] As the apostate Tzedoki clan which did not believe in the Oral Torah held that one may never eat hot food on Shabbos. Thus we suspect that one who follows this is part of this clan of heresy.

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