Shabbat 15

 

In today’s daf (Shabbat 15b) we continue our discussion relating to the enactments made by our early sages concerning the laws of ‘tumah’ – spiritual impurity.

According to Torah law, earthenware is susceptible to ‘tumah’. However, the Torah makes no mention of glassware. Given this, one of the enactments established by our sages was to rule that glassware was also to be considered susceptible to ‘tumah’, with the reason given for this decree that ‘since its very formation is from sand, our rabbis equated it to earthenware’.

However, notwithstanding the decree it is evident from the discussion on Shabbat 15b-16a that numerous sages challenged the assertion that glass should be likened to earthenware. In fact, on Shabbat 16a we find numerous opinions claiming that glassware should be compared to metalware since both can be melted down and then refashioned.

Sadly, while the laws of ‘tumah’ may be less applicable today, this debate continues with respect to kashering glassware – especially for Pesach.

According to those who compare glassware to earthenware, meaning that they treat glassware as something that absorbs but cannot extract (בולע ואינו פולט), then glassware cannot be kashered; whereas if glassware is comparable to metalware, meaning that if we treat it as something that both absorbs and extracts (בולע ופולט), then it can be kashered.

Basing themselves on our Gemara (Shabbat 15b), numerous authorities (R’ Yechiel cited in the Mordechai, Semag as cited in Terumat HaDeshen) claim that glassware should be treated as earthenware and therefore it cannot be kashered. Significantly, this is the Ashkenazic custom as noted by the Rema (OC 451:26).

Other authorities (Or Zarua, Ritva) adopt the view noted on Shabbat 16a (see also Avoda Zara 75b) that glassware should be treated as metalware. Given this, they claim that glassware can be kashered.

However, there is a further view found in Avot D’Rabbi Natan (41:6) and cited by numerous authorities (Tosfot, Rosh, Ra’avia, Ran, Rashba) which claims that glass neither absorbs nor extracts (אינו בולע ואינו פולט). Significantly, this is the view presented by R’ Yosef Karo in the Shulchan Aruch (OC 451:26) and followed by some Sefardim, although it should be noted that not all Sefardim follow this practice such as those who follow the customs of the Ben Ish Chai (see Sh’ut Rav Poalim Vol. 3 No. 29). However, according to R’ Ovadia Yosef (see Halichot Olam Vol. 1 96:9) if such Sefardim live in Israel, they may adopt this more lenient view.

Finally, some poskim treat Pyrex like glassware and assert that it cannot be kashered for Pesach, whereas others rule that Pyrex is unlike glassware and can be kashered. As with all matters of Jewish practice, if you have specific questions it is best to consult with your local orthodox religious guide.