Cheres - Glassware Status

QUESTION: May glass utensils be used interchangeably with both milchigs and fleishigs, and may a non-kosher glass utensil be used without kashering?

ANSWER: In a previous Halacha Yomis, we discussed a disagreement between the Shulchan Aruch and Rema about using chametz glass utensils on Pesach. Shulchan Aruch permits using glass utensil on Pesach even without kashering, while the Rema writes that the custom in Ashkenaz was not to use chametz glass utensils on Pesach even if kashered with hagalah. Is this custom only a chumra of Pesach, or does this apply all year as well?

There are three opinions in the poskim about glass year-round that absorbed non-kosher or dairy and meat.

Some poskim assume that the position expressed by the Rema in Hilchos Pesach that glass absorbs and cannot be kashered, applies year-round as well. This is the position of the Taz in OC 87:2. It is forbidden to daven or recite berachos in front of an earthenware commode, even if it is clean and does not have a bad smell. Shulchan Aruch (OC 87:1) writes that this does not apply if the commode is made of glass, since glass does not absorb. However, the Taz writes that since the Rema in Hilchos Pesach ruled that glass absorbs, a glass commode has the same status as one made of earthenware, and even hagalah would be ineffective. Clearly, the Taz understood that the ruling of Rema was not limited to Pesach but applies to all areas of halacha. Rav Belsky zt”l followed the Taz. He maintained that since the Rema did not specify that his ruling is limited to Hilchos Pesach, one must assume it was meant in all areas of halacha, as per the Taz, with the exception of yayin nesech, for which we find many other leniencies. Nevertheless, Rav Belsky agreed that when there are other mitigating factors one may kasher glass for year-round use (not for Pesach), since even the Rema agreed that bidi’eved kashering works for glass (as per Magen Avrohom, 451:49 who quotes the Rema’s work, Darkei Moshe).

Other poskim hold that the Rema only ruled that glass absorbs and cannot be kashered for Pesach, but year-round, glass does not absorb non-kosher or meat and dairy. The Pri Megadim (MZ 451:31) cites the opinion of the Knesses Hagedolah that we are only strict regarding glass for Pesach, but not in other cases. The Minchas Yaakov (85:12) as well writes that there is a seeming contradiction as to whether glass absorbs, since in Hilchos Yayin Nesech the Rema does not require kashering glass holding tanks that stored non-kosher wine. He suggests that Rema was only strict regarding Pesach. Igros Moshe (OC 5:32) seemingly accepted the opinion of the Minchas Yaakov.

A third position is a compromise: For year-round, glass absorbs but it can be kashered. This is the ruling of Dayan Weis in Minchas Yitzchok (1:86, 4)

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The Gerald & Karin Feldhamer OU Kosher Halacha Yomis is dedicated to the memory of Rav Yisroel Belsky, zt"l, who served as halachic consultant for OU Kosher for more than 28 years; many of the responses in Halacha Yomis are based on the rulings of Rabbi Belsky. Subscribe to the Halacha Yomis daily email here.