The status of glass:[1]

The three opinions: 1) Some Poskim[2] rule that glass is a hard and smooth material which cannot absorb the taste of foods and thus does not require Kashering 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.[3]] 2) Other Poskim[4], however, rule that glass has the same status as other metal vessels which absorb taste and must hence be Kashered prior to use from meat to milk or Chametz to Pesach. 3) Other Poskim[5], however, rule that glass has the same status as earthenware, and not only does it absorb taste of food, but can never be Kashered. 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-Chametz/Pesach: Practically, the custom amongst Ashkenazi Jewry is not to Kasher for Pesach any glass vessels which have absorbed Chametz.[6] However, Bedieved, if the vessel was used for hot Pesach foods, then if it was Kashered beforehand, the food remains permitted.[7] Furthermore, in certain cases the food remains permitted even if the vessel was not Kashered beforehand.[8] [Sephardim, however, are lenient to allow using Chametz glass vessels for Pesach even without Hagala, so long as the glass has been washed and cleaned well.[9]]

The final ruling-Other Issurim/Meat & Milk [Glass plates, cups, bowls]:[10] Although the Ashkenazi custom is to be stringent like the latter approach to not use Chametz glass vessels for Pesach even with Kashering, regarding other Issurim during the year, the Ashkenazi custom is to be lenient like the Sefaradim and use them even without Kashering.[11] Thus, the custom is to purchase old glass vessels from gentiles and use them after simply washing them clean, without Kashering.[12] Likewise, glass plates, bowls, and cups may be used 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.[13] Nevertheless, some Poskim[14] are stringent and rule that Ashkenazim are to be stringent with glass vessels just like on Pesach, and not switch their use between meat and dairy. 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.[15]

Glass cookware-Heat resistant glass such as Pyrex/Dulerex:[16] 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.[17] Some Poskim[18] rule it is more strict than regular glass and is forbidden to be used on Pesach and is forbidden to be used for cooking or baking of both meat and milk, and it must thus be designated for one food.[19] Likewise, the non-Kosher glass cookware of a gentile is forbidden to be used unless it is Kashered.[20] Other Poskim[21], however, rule it has the same status as all glass and may hence be used by Sefaradim 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.

Wine glasses-Glass vessels of a gentile used to drink and store Yayin Nesech:[22] It is permitted on occasion[23] to drink non-wine beverages from clean wine glasses, and other clean wine vessels, of a gentile without Kashering them in between even if they were used to drink and store Yayin Nesech. This applies even for Ashkenazim.[24] [This applies even if one lent the wine glasses to a gentile.[25] Thus, one may use wine glasses of a non-Kosher bar, hotel lobby, or restaurant to drink, so long as they are cleaned well beforehand.] However, it is forbidden to drink wine from a glass vessel of a Gentile that was used to drink or store wine, until it is Kashered through Shichshuch, which is accomplished by rinsing it well three times with water [even cold].[26] Likewise, if one desires to use the vessel on a permanent basis, then it is required to be rinsed well three times with [even cold] water prior to its use even for use of non-wine beverages.[27]

 

Summary: Ashkenazim: The Ashkenazi custom is not to use any Chametz glass vessels on Pesach even if they are Kashered. 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 Kashered. 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 Sefaradi 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 Sefaradi 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: Many Poskim[28] rule that glass material does not absorb, and hence if a clean glass Ben Yomo meat pot cover was used for cooking milk, one only requires 60x versus the non-glass material that is on the pot [i.e. the metal rim, or screw for the handle]. If the cover was dirty with meat food then one requires 60x versus the food, but not versus the glass material. Practically, the Sefaradim are lenient and it is possible that even Ashkenazim may be lenient in this matter, upon discussing with a Rav.[29] Certainly if the cover was not Ben Yomo the food is permitted, even in the communities who are stringent to give a non Ben Yomo cover the same status as Ben Yomo.

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

[2] 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

[3] Admur ibid

[4] 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 Kasherable; 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 Hagalah they are like metal.”; See also Shibulei Haleket; Ritva Pesachim in name of Reah

[5] 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

[6] Admur ibid; Rama ibid; Iggur ibid; Aruch Hashulchan Y.D. 120:25

[7] Admur ibid; M”A 451:49; M”B 451:155; See however Taz 451:30 who is lenient even if the vessel was not Kashered at all, as explained in P”M 451 A”A 49

Time of need: Some Poskim rule that in a time of need, if there are no other cups or vessels available, one may be lenient to Kasher the vessel with Hagalah or Miluy Veiruiy. [Chayeh Adam; M”B 451:156 and Shaar Hatziyon 451:201]

[8] Bedieved: If one placed hot Pesach food in a glass Chametz vessel, then if the vessel was most commonly used for cold Chametz that did not soak in it for periods of 24 hours, while hot Chametz and soaking Chametz for 24 hours was its minority usage, the food remains Kosher [if the vessel was not Ben Yomo]. If, however, the vessel was majority used for hot Chametz foods, or for soaking cold Chametz for past 24 hours, then the Pesach food may not be eaten, if the vessel did not have Hagala or Iruiy Vemiluiy done to it. If the vessel was Kashered, then the food remains Kosher in all cases. [Admur ibid; M”A 451:49; M”B 451:155; See however Taz 451:30 who is lenient even if the vessel was not Kashered at all, as explained in P”M 451 A”A 49] If the hot Pesach food was poured from a Keli Sheiyni onto the vessel, then seemingly the food likewise remains permitted, even if the vessel was majority used for hot Chametz, and even if the vessel was not Kashered. Vetzaruch Iyun. If the vessel is not Ben Yomo at the time of use, some Poskim are lenient in a case of great loss. [M”B 451:155]

[9] Beis Yosef 451:36 that so is the ruling and custom; As so rules Michaber ibid; Yechaveh Daas 1:12; Yabia Omer Y.D. 4:5; Yaskil Avdi 5 Y.D. 13; 8:33; However, some Sefaradim are stringent to Kasher the vessel. [Rav Poalim 3:29 that so is custom of Bagdad; Sefer Hakashrus ibid footnote 147 that many are accustomed to soak for three days] Others are stringent not to use it at all as rules the Rama. [Sdei Chemed Mareches Hei 29]

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

[11] 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 Kashering.”; 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.”; See Hakashrus 3:53 that the Ashkenazi custom is to be lenient to Kasher them; See Admur 87:2 regarding a glass potty and in Kuntrus Achron 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”;

[12] Aruch Hashulchan ibid

[13] 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]

[14] 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 Kasher the glass, but not to use without Kashering [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]

[15] 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 Geodlei Yisrael of the previous generation, and hence I do not want to swerve from the custom of my mother’s house.”

[16] See Piskeiy Teshuvos 451:54

[17] 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 Kashering 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 Kashers the vessel in between as one may come to forget to Kasher it, and the same should apply here, as one may forget to clean the vessel.

[18] Tuv Taam Vedaas 2:25 [regarding glass lamps of Cheilev]; Mahram 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 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 Kashered? Yes, it may be Kashered through Hagalah. [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 Kashered even by other Issurim.

[19] 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 Kashers the vessel in between as one may come to forget to Kasher 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]

[20] Poskim ibid

Other opinions: See article of Rav Braun in Koveitz Hearos ibid who concludes Ashkenazim are stringent even by other Issurim that it cannot be used even in Kashered.

[21] 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]

[22] Michaber Y.D. 135:1 [Not a problem by any vessel unless wine is stored in it for a while]; 135:8 [By glass is not a problem even if stored in it]

[23] See Shach 137:16 on Michaber 137:4 that even if one plans to use it for non-wine beverages, it may not be used “Derech Keva” until it is properly Kashered, as rules Rama 121:5 regarding all non-Kosher vessels, and the proper Kashering for a glass vessel is Shichshuch, as rules Michaber 135:1; See Imrei Eish Y.D. 44; Darkei Teshuvah 137:11

The reason it is only permitted on occassion: As the one may come to use the cup with wine, which will absorb the taste of the Yayin Nesech and become forbidden. [See Shach 137:15-16]

Other opinions: Some Poskim rule that one may drink non-wine beverages from the cup on an even permanent basis without Kasheirng it beforehand. [Kneses Hagedola 137:23; Chochmas Adam 81:12; See Imrei Eish Y.D. 44; Darkei Teshuvah 137:11]

[24] M”A 451:48 “Although we are stringent by Chametz, do not compare it to Yayin Nesech, as many leniencies apply by Yayin Nesech”; Rama ibid omits writing any gloss on this statement of Michaber ibid, and so is implied from Shach 135:23 and Taz 135:11 who both comment on this ruling and explain that glass is smooth and does not absorb.

[25] See Michaber and Rama 136:1 that vessels designated for wine require a Chosem and otherwise need to be Kashered; However, see Shach 136:3 that the entire stringency here is because it’s as if he entered it for storage, and hence since by glass we are lenient even if it is entered for storage, therefore it does not need to be Kashered.

[26] Michaber Y.D. 135:1 that Shichshuch is required, and 135:11 that Shichshuch requires rinsing of three times, and 137:4 from where it is evident that this applies only when one desires to drink wine from it

[27] See Shach 137:16 on Michaber 137:4 that even if one plans to use it for non-wine beverages, it may not be used “Derech Keva” until it is properly Kashered, as rules Rama 121:5 regarding all non-Kosher vessels, and the proper Kashering for a glass vessel is Shichshuch, as rules Michaber 135:1; See Imrei Eish Y.D. 44; Darkei Teshuvah 137:11

The reason: As one may come to use the cup with wine, which will absorb the taste of the Yayin Nesech and become forbidden. [See Shach 137:15-16]

Other opinions: Some Poskim rule that one may drink non-wine beverages from the cup on an even permanent basis without Kasheirng it beforehand. [Kneses Hagedola 137:23; Chochmas Adam 81:12; See Imrei Eish Y.D. 44; Darkei Teshuvah 137:11]

[28] See Chapter ?? Halacha ?? for the full details of glass material!

[29] See Chapter ?? Halacha ?? for the debate amongst the Poskim as how to rule in a case that the glass is on the fire.

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