Acid dyes as best for solid-color dyeing of silk. I personally use the reactive dyes on silk because they are so simple and can be done in the washing machine. However, on silk, the reactive dyes do not come out the same colors as on cotton, so it requires experimentation to get what you want. If you want true-to-swatch silk colors and want to experiment with the acid dyes, they require very hot water, either in the washer, or on top of the stove. Acid dyes will also dye nylon.