Similarly, [if a piece of] cloth that was woven [to the size] of three [fingerbreadths] by three [fingerbreadths] contracted corpse-tumah, and [subsequently] one finished the whole [piece of] cloth, and afterward one thread was removed from the original [cloth], it becomes tahor from corpse-tumah; but it is tamei [due to] contact with a t’mei meis. [If] one thread was removed from the original [cloth], and subsequently one finished the whole [piece of] cloth, it is tahor. Because [the Sages] said: [If a piece measuring] three [fingerbreadths] by three [fingerbreadths] is lessened, it is tahor. But [if] a piece measuring] three [handbreadths] by three [handbreadths] is lessened, even though it is not susceptible to midras tumah, it is [still] susceptible to all other forms of tumah.

[Concerning] a sheet that contracted midras tumah and was [then] made into a curtain, it becomes tahor from midras [tumah], but it is tamei [due to] contact with a midras. R’ Yose said: Why, which midras did this [sheet] touch? Rather [it contracts contact-tumah] only if the zav himself touches it, [rendering] it tamei [on account of] the zav’s touching.