Application of diphenols for dyeing

An alternative to the normal dyeing route to achieving colour in leather is to exploit the chemistry of creating the natural skin and hair pigments, melanins. 1,8-dihydroxynaphthalene and other dihydroxynaphthalenes can be oxidised and polymerised to create pigment products by reactions catalysed by laccase, a polyphenol oxidase. They not only create colour, but, if the reactions are conducted in the presence of collagen, the pigments are bound to the collagen by covalent bonds, which confer a tanning effect.