Dye-fibre association

The first synthetic dyes for wool were acid dyes, a class of dye that has since grown into a large, diverse, versatile and widely used group. Acid dyes are sufficiently soluble to allow direct application from an aqueous solution. Some acid dyes may also be used for coloration of other animal fibres, including silk, and also of nylon, which like protein fibres has both amide linkages and amino groups in its structure.