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Non-Kosher Oven – Kashering

I’m moving into a new house and the oven is included. Is there a way I can make it kosher?

The Aish Rabbi Replies:

Mazal tov on your new purchase first of all!

The basic rule with making non-kosher vessels kosher again is that the same process by which it became non-kosher must be used to make it kosher again. The metal walls of an oven absorbed the taste of non-kosher food via intense heat. The same degree of heat is required to burn out that taste.

If the oven is self-cleaning, then the process is straightforward. The self-cleaning cycle, which brings the oven to 900 F, is considered the equivalent of burning out the oven with fire. It thus burns out the non-kosher in the oven walls and racks – together with destroying any remaining food residue on the oven surface. Thus, all you need to do is wipe out any remaining pieces of food in the oven, put it on self-clean for a full cycle, and it is kosher.

A conventional oven is a bit more questionable. Its hottest temperature, of about 500 F, is not the equivalent of fire, but it does heat the oven to the hottest temperature it was used when it cooked non-kosher. Thus, the following process should be done and is sufficient:

(1) Clean the oven thoroughly with caustic cleaner. (Try to clean it entirely, but if there is a small amount of residue left which does not come off, it is okay.)

(2) Wait 24 hours since the last time it was used.

(3) Turn it on to its hottest temperature for one hour.

This process is sufficient for making the oven itself kosher. The racks, however, which likely absorbed food directly, should be replaced.

(Sources: Sefer Hagalas Kelim p. 446, Kashrus B'Mitbach p. 77, p. 80:17 (34-5), The Laws of Kashrus pp 230-31.)

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