Benny Danon from Istanbul, Turkey wrote:
I will ask something about Pyrex kitchen instruments. Is Pyrex considered glass or pottery? If it's non-kosher, can we make it kosher? (Note: I need a Sephardic answer.) Thanks for now. Shabbat Shalom.
Dear Benny Danon,
Sephardic Jews follow the ruling of the Shulchan Aruch which states that glass is non-absorbent. According to this, a glass utensil can never become non-kosher. Similarly, it can never be considered "dairy" or "meat," meaning that you can use it alternately for both milk and meat, cleaning it out well between use.
Pyrex is glass that is reinforced with other materials. This raises the question: Does Pyrex have the same halachic status as glass or not? While there is a dispute about this matter, Rabbi Ovadia Yosef, shlita, rules that Pyrex has the same status as glass. Most sephardic Jews follow this ruling.
(Ashkenazic Jews follow the ruling of the Rema that glass can become non-kosher and cannot be made kosher again.)
- Shulchan Aruch Orach Chaim 451:26
- Yechave Da'at 1:6