Is it permissible to use substances like salt in cleaning menstrual blood?
Chapter on what purification is achieved with regarding water
Al-Mughni
Book of Purification
Primary text
It is good practice to use a substance that removes the blood, such as salt or other agents, in the cleaning process. Evidence for this is narrated by Abu Dawud, where the Prophet, peace be upon him, instructed a woman who experienced menstruation to take a vessel of water, add salt to it, and then wash the bloodstain on the saddlebag.
Supporting text
Based on this narration, scholars permit the use of salt in purifying clothing from blood. By extension, using honey for washing clothes if soap ruins them, vinegar if ink stains them, rubbing hands with bran, or using watermelon and broad bean flour for washing hands and other similar substances possessing abrasive or cleansing power are also permissible.