Halacha for Wednesday 16 Tammuz 5780 July 8 2020

The Laws of Glassware and Pyrex Regarding the Prohibition of Milk and Meat Mixtures-Continued

In the previous Halacha we have written that according to Maran Ha’Shulchan Aruch, glassware does not absorb any flavor from foods placed in it and thus, there is no prohibition to use a glass vessel for meat and then after it is washed well, to use it for dairy (although the Rama does rule stringently that glass shares the same law as pottery; this is indeed the prevalent custom among many Ashkenazi Jews).

Maran Rabbeinu Ovadia Yosef zt”l ruled in his works and Torah lectures in accordance with the opinion of Maran Ha’Shulchan Aruch that glassware does not require Hag’ala and it may be used for both meat and dairy. There were those who challenged the ruling of Maran zt”l by claiming that although Maran Ha’Shulchan Aruch rules that glass does not absorb, nevertheless, the glass produced today is different than the glass that existed in previous generations. They supported this claim with an experiment which showed that a used glass weighed slightly more than a new glass and they claimed that this was a result of the fact that the glass absorbed some of the liquid stored in it in addition to other such proofs that glassware absorbs.

Nevertheless, nothing has really changed, for Rabbeinu Nissim writes that although glassware does absorb, however, since its absorption is much less than other forms of dishes, this is not enough of a reason to prohibit using it for both meat and dairy. Thus, all of the above experiments proving that glass does absorb are meaningless, for the absorption is so miniscule that it is insufficient to create a prohibition.

Maran Rabbeinu Ovadia Yosef zt”l writes that just as it is permissible to use glass dishes for both meat and dairy or for both Chametz and Pesach according to the Sephardic custom, the same leniency applies to dishes made of “Pyrex” which is heat-resistant, for this material is also considered glass and does not absorb. He writes furthermore that even according to the Ashkenazi custom that glassware shares the same law as pottery and cannot be koshered even through Hag’ala, nevertheless, Pyrex and other heat-resistant glassware (such as “Corelle”) may be koshered by means of Hag’ala, for the reason why the Poskim write that glass cannot be koshered through Hag’ala is only because of the concern that one would not perform the koshering process correctly out of fear that vessel will explode because of the intense heat of the boiling water and not because they are like pottery which cannot release the flavor it has absorbed through Hag’ala. However, there is no such concern regarding heat-resistant glass and even according to the Ashkenazi custom, such dishes may be used for meat and then dairy when Hag’ala is performed in between them. This is indeed the opinion of Hagaon Rabbeinu Yosef Shalom Elyashiv zt”l. The Responsa Tzitz Eliezer rules that there is room for leniency in this regard when Hag’ala is performed three times. According to the Sephardic custom, however, a thorough washing is sufficient, as we have explained.

Ask the Rabbi


8 Halachot Most Popular

The Customary Order of Rosh Hashanah

It is customary to eat certain symbolic foods during the two nights of Rosh Hashanah which signify good fortune for the entire upcoming year. It is therefore customary to eat black-eyed peas, pumpkin, leek, spinach, dates, pomegranates, apples dipped in honey, and meat of a sheep’s head on the......

Read Halacha

The Blessings on Thunder and Lightning

One who sees lightning recites the blessing, “Baruch Ata Hashem Elokeinu Melech Ha’Olam Oseh Ma’aseh Bereshit.” One who hears thunder recites the blessing, “Baruch Ata Hashem Elokeinu Melech Ha’Olam She’Kocho Ugvurato Maleh Olam.” Until When Can On......

Read Halacha

The Laws of Mentioning “Mashiv Ha’Ruach”

We Begin Reciting “Mashiv Ha’Ruach” “Mashiv Ha’Ruach U’Morid Ha’Geshem” is a praise we recite to Hashem during the winter months within the “Mechayeh Ha’Metim” blessing of the Amidah as is printed in all Siddurim. We begin recitin......

Read Halacha

Speaking Between Washing One’s Hands and the “Hamotzi” Blessing

Question: Is one permitted to speak between washing one’s hands and reciting the Hamotzi blessing? Answer: The Gemara in Masechet Berachot (42a) states: “Immediately following hand-washing, one must recite the blessing.” The Rishonim disagree as to the explanation of this Gemara......

Read Halacha


“Double Bread”

In the previous Halacha, we have explained the laws of Seuda Shelishit and would also like to discuss the laws of women regarding Seuda Shelishit. However, since this issue is connected to the laws of women and “double bread” on Shabbat, let us first discuss the basic laws of “doub......

Read Halacha

Chol Ha’Mo’ed

The days between the first and seventh days (outside of Israel between the second and eighth days) of the Pesach holiday and the days between the first day of Sukkot and the holiday of Shemini Atzeret (outside of Israel between the second day of Sukkot and Shemini Atzeret) are called “Chol Ha&......

Read Halacha

One Who Hears Thunder at Night

Question: If one hears thunder at night while sleeping, may one recite the blessing on thunder without washing his hands? Also, must one recite a blessing on lightning every time one sees it or is once a day sufficient? Answer: In the previous Halacha we have established that one who sees lightni......

Read Halacha

Using Frozen Bread for “Double Bread”

We have already discussed that there is a Mitzvah to recite the Hamotzi blessing during the Shabbat meals on “double bread,” i.e. two loaves of bread. It is fairly common that one does not have two loaves of bread for this Mitzvah and would like to join a frozen loaf of bread from the fr......

Read Halacha