Kashering Glass

Can Glass be Kashered?

There are three differing opinions among poskim on the subject of kashering glass, namely: 

Glass doesn’t absorb, and therefore there is no need to kasher a glass utensil. It only has to be washed and wiped clean.  

The opinion on the opposite end of the spectrum is that glass does absorb, and that this absorption is irreversible and cannot be kashered

The middle-ground opinion is that glass, like most other materials, needs to be kashered if it becomes treif, and can in fact be kashered.

The Sephardic custom is to be lenient and follow the first view. Ashkenazim, although they concur with the third view in principle, are stringent in practice and do not kasher glass. Some argue that this stringency only applies to Pesach glassware—that is to say, we never rely on kashering glass to remove chametz—but others are stringent all year round. #462?

https://halacha2go.com?number=462

Practical Halacha: One minute a day. By Horav Yosef Yeshaya Braun, shlita, Mara D'asra and member of the Badatz of Crown Heights.