Alum Potassium Sulfate
Alum Potassium Sulfate (or potassium aluminum sulfate, also known as potash alum) is the mordant most frequently used by natural dyers for both animal (protein) and plant (cellulose) fibers and fabrics. When dyers simply refer to "alum" this is usually what they are referring to. It improves light and washfastness of all natural dyes and keeps colours clear. It is inexpensive and safe to use (but should not be ingested). This form of alum is refined from bauxite, the raw state of aluminum ore, and is free from other impurities such as iron. Use at 12-20% WOF.
