alum

This substance is primarily recognized for its astringent properties, which cause tissues to contract and blood vessels to constrict. In a medical or grooming context, it is used as a styptic to quickly seal small wounds, creating a sharp, stinging sensation upon application. In industrial applications, it serves as a mordant in dyeing, ensuring that pigments bond permanently to fabric. It is also a key agent in water treatment for coagulation, where it helps clump impurities together for easier removal.