[If] her dough became dimua before she thoroughly mixed [it], [it] is exempt [from challah], for a dimua mixture is exempt [from challah]. But [if the dough became dimua] after she thoroughly mixed [it], it is obligated [in challah].  [If] there arose in [the dough] an uncertainty of tumah before it was thoroughly mixed, it may be made in tumah; but if after she thoroughly mixed [the dough], it must be made in taharah.