Download Safety Data Sheet The basics (Aka Sodium Sulfate) Improves the yield of Fiber Reactive Dye. (Gives more intense color). The benefits Use in place of, and in the same proportions as, plain salt.  The uses Also used as a leveling agent for production dyeing with Leveling class Acid Dyes for wool and silk to get the most even results. The pro tip Approximately 1 1/4 cups per lb, but that can vary based on the density.