An oven that came in pieces from the artisan’s workshop, and he made hoops for it, when he puts them on [the oven] it is [still] tahor [and then] it is tamei. [If] he removed its hoops, it is tahor. [If] he returned [the hoops] to [the oven] it is tahor. [If] he plastered it with clay it becomes susceptible to tumah, and he need not heat it, since it was already heated.

[If] one cut [the oven into] segments and placed sand between the segments, R’ Eliezer rules [it] tahor, but the Sages rule [it] tamei; this is the oven of the [coiled] serpent. Arabian cauldrons that one digs in the ground and plasters with clay: If the clay can stand on its own, it is tamei, but if not, it is tahor; and this is the oven of Ben Dinai.