Ingrain dyes (developed dyes) -
Ingrain dyes are those that are synthesised straight on the fabric. Instances of this type of dyes are azo dyes. In this the fabric is wrapped up in the solution of coupling reagent commonly a phenol or naphthol. After that it is dished in the solution of appropriate diazonium salt. Both react to make the dye whose molecules are adsorbed on the surface of fabric. The ingrain dyeing is chiefly appropriate for cotton fabrics.