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.