A Microwave Oven Used for Non-Kosher Food

My housekeeper warmed up her non-kosher lunch in my microwave oven. Can it be kashered?

The inside of a microwave oven is mostly made of plastic and glass. The walls of the microwave are plastic, but the turntable and window are made of glass; in addition, some microwaves have metal racks. While most poskim hold that plastic can be kashered for year round use, with regard to glass Rama (Orach Chaim 451:26) writes that the minhag (custom) of Ashkenazim is not to kasher glass. There is discussion as to whether Rama’s stringency against kashering glass was limited to Passover or was intended to apply all year round as well. Rav Belsky, zt”l held that regarding oven doors one may be lenient, provided the food did not directly touch the glass. However, if the non-kosher food was placed directly on the glass turntable without the separation of a plate or container, the glass plate should be replaced (or double covered in plastic wrap).

The exact process of kashering a microwave will be discussed in the next Halacha Yomis.