Jacquard Acid Dye for Wool, Silk and Other Protein Fibers, 1 Pound Jar, Concentrated Powder, Jet Black 639Formulated Especially For Silk, wool, feathers, nylons, and other protein fibers, Jacquard Acid Dye ensures vibrant, long lasting colors Consistent Professional Results Highly concentrated powdered hot water acid dye delivers level, uniform color during immersion dyeing Exceptional Colorfastness Jacquard Acid Dye, available in various colors, resists bleeding and fading, preserving brilliance with washing Multipurpose Fabric Dye Use for yarn dyeing,