Acid dyes are used to color silk, wool, feathers, other protein fibers nylons, and paper and nothing does it better! Extremely brilliant and colorfast, Acid Dyes are highly concentrated, powdered hot water dyes that produce level, uniform color during immersion dyeing. They exhaust well and wonâ??t bleed or fade with washing. Of all the colorants in the world, acid dyes are known to produce the most luscious colors of all, and is unsurpassed for quality, intensity and consistency.