Conventional Oven, Kashering Back and Forth

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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.

This column comes from OU Kosher’s Halacha Yomis dedicated in memory of Rav Chaim Yisroel ben Reb Dov HaLevy Belsky, zt’l, Senior OU Kosher Halachic Consultant (1987-2016). Subscribers can also ask their own questions on Kashrus issues and send them to These questions and their answers may be selected to become one of the Q and A’s on OU Kosher Halacha Yomis.



  1. Honestly the lomdus is pretty weak. It’s as if a conventional oven you are taking the lenient position, yet when presenting the earlier Sheila of microwave you said not to rely on lenient. A microwave in it of it self may never need to be kashered according to many. Only if there are real pieces of food inside, is there a problem. Furthermore, prior steam is a problem more likely in a conventional over where there is בליאה issues vs a microwave that might never be an issue.

  2. A self-cleaning oven is libun gomer, so there should be no problem kashering back and forth, even a million times.

    And, you don’t have to wait m’eis l’eis.

  3. These are abbreviated halacha listings and don’t discuss everything, e.g. ben yomo. Readers who are not familiar with the relevant halochos should realize that this article (and yesterday’s too) aren’t comprehensive.


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