653. Removing Hair, Bleaching
Shabbos 9:9
In order to be liable for removing hair with an instrument, one must remove two hairs. If a person removes a gray hair from among dark hairs, then he is liable for removing just one. If the better part of a nail has split, or if strips of skin have started to peel, if they have split upward and are bothering a person, he may remove them by hand but he may not use an implement. If one did remove them with an implement, he would not be liable. If the nail or skin does not bother the person, he is not permitted to remove them even by hand. If the majority of the nail has not split, it is likewise prohibited to remove it by hand, and one who removes it using an implement would be liable.
Shabbos 9:10
If a person bleaches wool, linen, silk or other fabrics that are normally bleached, he is liable. The minimum amount for which one would be liable is enough to make a thread twice the distance from one’s thumb to his forefinger extended, which is equal to four handbreadths.