Q. I only have one oven which I use for fleishigs, and occasionally, when I need to bake something dairy, I kasher it. When I am finished, I kasher it again to use for fleishigs. Is this permitted?
A. We have previously seen that a microwave oven should not be kashered back and forth from milchigs to fleishigs, since we are concerned that one may forget the status of the microwave and might inadvertently cook dairy in it after using it for meat. However, Rav Hershel Schachter said that there is reason to be lenient with regard to kashering a conventional oven.
In a conventional oven, the food is always placed in pans and does not directly touch the surfaces of the oven. Additionally, an oven will not fill with steam to the same degree as a microwave. Therefore, according to some opinions, if one did not kasher a fleishigs oven before using it for dairy, the food would be still be permitted. (If one actually did so, they should discuss with a rabbi.)
The Beis Yosef (Yoreh De’ah siman 2) writes that we are not concerned that one will forget to remedy a situation if even in the event that they were to forget, the food would still be permitted. Therefore, Rav Schachter said that since many people do not have the luxury of owning two ovens, they may rely on the lenient opinion in regards to kashering the oven between meat and dairy. Furthermore, Rav Schachter said that one may do the same with their microwave oven if they are careful to always place the food inside a bowl and place a cover on top. This way there is no direct contact with the microwave, and the cover will keep most of the steam contained inside the bowl.
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