Koshering Earthenware and Glass for Pesah

While discussing an earthenware vessel in which sacrifices were cooked, the Torah (Vayikra 6:21) and the Gemara (Pesahim 30b) explain that such a vessel can not be cleansed by conventional immersion into a Mikve, and that only breaking the vessel will render the resultant pieces pure. By extension, the Shulhan Aruch (Orah Haim 451:1) says that an earthenware vessel in which hotHametz was cooked throughout the year cannot be koshered by Haga’ala(immersion into boiling water). Although Libun (heating with a flame) would technically work, there is a concern that one would not do it to a satisfactory level out of fear of bursting the vessel. However, placing such a vessel into a kiln, or nowadays, a self-cleaning oven, would render it kosher for Pesah, albeit with the risk of shattering. It should be noted that aforementioned laws apply to both glazed and unglazed earthenware.

Unlike porous earthenware which has the capacity of absorbing residual Hametz, the Shulhan Aruch (Orah Haim 451:26) rules that glass is not absorptive. Therefore, the Sephardic custom, including that of the Moroccan community, is that glass need only be cleaned for use on Pesah.

Summary: Unless one uses the heat of a self-cleaning oven, earthenware vessels cannot be koshered for Pesah. Glass vessels require no special koshering.