About acid dyes
Acid Dyes are the dye of choice for dyeing all protein fibers, like wool and other animal hair like alpaca, angora, mohair, etc., silk, feathers, and also they dye nylon. They are even used on leather sometimes. These concentrated powdered dyes are used primarily for tub-dyeing yardage or clothing, or tub dyeing or painting on protein yarns & roving. They require very hot water to work properly. The other thing needed (as a fixative) is household white vinegar or a mild powdered acid like Citric Acid.
Acid dyes are very concentrated, react fast, and the results are very permanent for most colors - light and wash fast! The end color depends on the temperature, how much dye you use, how acid the dye-bath is, how long the fabric is in the dye, and how much fabric you have. And as with all dye powders, you should handle them carefully. Common sense and good housekeeping (dust mask, gloves, proper ventilation, etc.) should always be used when handling any dye or chemicals. Keep out of reach of children and pets.