Can you kasher pyrex

The Terumat Hadeshen rules in accordance with this opinion regarding Pesach. The Ritva Pesachim 30b s. Li'avid cites the Ra'ah who adopts a middle approach. He rules that while we do believe that glass absorbs taste particles from food, it nevertheless may be Kashered. He reasons that since the laws of Toveling utensils and Kashering utensils are linked by the Torah Bamidbar the rules of these two areas of halacha should be compared. Thus, just as glass is assigned the status of metal in the context of "Toveling" utensils, so too glass is assigned the status of metal in the context of Kashering.

The Rosh, however, rules that one should not Kasher glass, due to concern that one may not Kasher it properly because of fear of breaking. Accordingly, three opinions appear in the Rishonim whether glass may be Kashered.

One opinion is that it cannot be Kashered, a second opinion believes that it may be Kashered, and a third opinion is that it does not even absorb any food particles and thus there is never a need to Kasher glass. This controversy persists in the Shulchan Aruch as well. The Mechaber rules that glass does not absorb and may be used on Pesach without Kashering even if hot Chametz touched it.

Rav Yosef Karo believes that thoroughly washing the glass utensil prepares the item for Passover use. The Rama takes the opposite approach. He rules at least in the context of Pesach that glass can not be Kashered. He notes that this is the commonly accepted practice among Ashkenazim. Indeed, the aforementioned Terumat Hadeshen already notes that this was the accepted practice among Ashkenazim. It should be noted that the Terumat Hadeshen is a major source for the Rama's rulings.

The Mishna Berura cites the Chayei Adam who rules that in case of extraordinary need where one is unable to procure new glasses for Pesach one may Kasher glass. Accordingly, it may is possible that Ashkenazim should remove the glass tray from a microwave oven for Pesach use, because the Ashkenazic tradition is hold that glass cannot be Kashered for Pesach use, barring extraordinary circumstances.

One should ask his Rav for guidance regarding this issue. For a review of the opinions regarding Kashering glass for use on occasions other than Pesach, see this author's article published on the Journal of Halacha and Contemporary Society Fall , pp.

Rav Waldenburg believes that since these materials are not identical to glass, one cannot assume that Rav Karo would rule that they do not absorb food particles. In cases of difficulty, some are maikel to allow libun kal, since the Magen Avrohom said that if one kashered glass it would help bedieved.

Glass lined reactors glass lined steel accordingly may be kashered with hagalah. Although we do not kasher glass, we allow caterers to use hotel glasses. This is because the glasses are clean and are only used with cold drink. Rama Y. Caterers may not wash their own glasses in a treif hotel dishwasher, since this will make their glasses treif, and continued use is considered derech kevah. Some pipes have a sight glass for viewing product. If hot non-kosher product flows through this pipe, can it be kashered?

Heter includes chalav stam provided that the kli being kashered is aino ben yomo. If the bliya was from other issurim, it is subject to the machlokes the Mechaber and Rama, and our minhag is not to kasher lichatchila. Fiberglass is a material made of thin strands of glass that are pressed together to form a board.

Plain fiberglass is highly porous and cannot be kashered. However, fiberglass mixed with resin forms a solid non-porous surface. Study in Israel Explore Judaism Audio. Ask The Rabbi Ask! Search the Database. Possibly Related. Animals, Genetically Altered, Kasherus. Ohr Somayach International is a c3 not-for-profit corporation letter on file EIN and your donation is tax deductable.