Chapter 159 – Putting on White Linen and Counting the Clean Days
159.1) A woman who perceives blood during her period of purity should count five pure days, including the day on which she perceived the flow.
159.2) When traveling, if a woman cannot obtain enough water to wash herself, it does not retard the “end of her menstrual period.” She should wipe herself as best she can.
159.3) If the fifth day is a Sabbath or prayer day, the woman should consult an authority to determine her cleanliness.
159.4) A man may instruct his household to insert cotton until twilight to check that the end of a menstrual period has come.
159.5) Some communities ask that a woman postpone the putting on of white linen if her final day is on a Sabbath or a festival.
159.6) During the seven clean days, a woman should examine herself twice daily.
159.7) All examinations should be made with an old white linen cloth or with a soft white woolen cloth, and inserted to a depth that the male organ penetrates.
159.8) Make the examination in the light of day, not in artificial light.
159.9) If she finds a stain, she may consider her menstruation as just ended.
159.10) Exceptions exist for a bride before her wedding. (See source for details, or consult a rabbi.)