Pidyon

What materials can be kashered by hagala? What materials can't?

• Clay or China: Earthenware cannot be kashered.
• Corelle: Some hold that Corelle has the law of glass. Others hold it is cheres (earthenware) and cannot be kashered.
• Corningware: Some hold it has the law of glass. Others hold it is cheres and cannot be kashered.
• Duralex: Some hold it has the law of glass. Others hold it is cheres and cannot be kashered.
• Fiberglass: Fiberglass is considered the same as earthenware and cannot be kashered. It is made of compressed fibers of glass and has microscopic pores similar to clay.
• Glass. Whether or not glass can be kashered by hagala is a subject of debate. (See the Piskei Teshuva on Orach Chaim Simon 451.)
  1. Some hold that hold glass does not absorb and therefore does not need kashering.
  2. Others hold that glass is like metal and can be kashered through hagala.
  3. Others hold that glass is like clay and cannot be kashered.
  Sephardic Jews generally hold like the first opinion, though not with regard to Pesach. I have seen Ashkenazic Jews follow any one of these three opinions. Due to the varying opinions on this matter, it is incumbent on each person to ask the opinion of their rabbi. Also, please note that the halacha regarding kashering glass for Passover use may be different than for general kashering, so again please consult with your rabbi.
• Porcelain is like earthenware cannot be kashered.
• Porcelain Enamel: Some hold it has the law of glass. Others hold it is cheres.
• Plastic: Some hold it has the law of glass. Others hold it is cheres.
• Pyrex: Some hold it has the law of glass. Others hold it is cheres.
• Teflon Coated Pots can be kashered by hagala.
• Teflon Coated Pans: If food was cooked directly on the pan with little or no oil, it must be kashered by libun (direct fire). Since this would ruin the Teflon, you must ask advice of your rabbi. In some cases, hagala can be done.

There are also many other modern man-made materials that generally fall into one of the above categories. Note that there is a fundamental argument in kashrut over all these materials: some say that all materials can be kashered unless the Torah states otherwise while others say that the Torah listed only those materials that are able to be kashered and all others are not. Consult with your rabbi for the proper custom.

Questions to ponder:

• What other hagala guidelines should I follow?
• How do I kasher by libun?