משנה על נגעים 2:4

There are [laws] that apply to white hair that do not apply to quick flesh, while others apply to quick flesh and not to white hair. White hair causes uncleanness in a boil and in a burn, whether growing together or dispersed, and whether encompassed or unencompassed. There are [laws] that apply to quick flesh, for quick flesh causes uncleanness in scalp baldness and in forehead baldness, whether it was turned or was not turned, it prevents the cleanness of one who is turned all white, and causes uncleanness whatever its color, and these do not apply to white hair.

One who touches the upper beam, the lower beam, the harnesses, the sley, the thread that is drawn over purple material, or a spool which is not to be shot back, remains clean. If he touches the woof, the standing warp, the double thread that is drawn over purple material or a spool which is to be shot back, he becomes unclean. If one touches the wool that is on the distaff, or on the spool, he remains clean. If he touches the spinner: Before it was uncovered he is unclean, After it was uncovered he remains clean.