This is the mordant to use for protein fibers such as silk and wool, and is the traditional mordant used worldwide since antiquity. Alum is refined from bauxite and is a transparent crystal, resembling salt. We supply a food grade alum that is free of iron and other impurities.
You can use between 10-20% alum on the weight of fiber. 250 grams will mordant about 2500 grams (5.5 lbs) at 10%
Check out our How To Mordant instructions for detailed information on preparing your fibers for natural dyeing.