Potassium Alum Sulfate is a pre-mordant for all fiber types. Use 7-10% of weight of dry silk or wool. Protein fibers: Soak clean fiber in warm water for 1 hour, then add to readied mordant pot. Simmer 1 hour (don't boil), remove from heat and soak 2-24 hours, stirring a few times. Rinse and proceed with dyeing.