An oven that contracted tumah, how is it rendered tahor? One divides it into three [sections] and scrapes off the [clay] coating down to the ground. R’ Meir says: It is not necessary to scrape off the [clay] coating nor [is it necessary to divide it] down to the ground; rather, one reduces it from within [to less than] four handbreadths. R’ Shimon says: And it must be moved. [If] one divided it into two [sections], one large and one small, the larger [section] is tamei and the smaller [section] is tahor. [If] one divided it into three [sections], [such that] one [section] was as large as [the other] two, the larger one is tamei and the two smaller ones are tahor.

[If] one cut [the oven into] segments along its width, [each segment that is] less than four handbreadths is tahor. [If] one plastered it with clay, it becomes susceptible to tumah from when he heats it enough to bake sponge cakes in it. [If] one distanced the [clay] coating from it and placed sand or pebbles between them, of such [an oven] they said: A niddah and a woman who is tahor may bake in it and it is tahor.