The Reaction of Wool Keratin with Tetrazonium Cations

A novel dyeing method is described in which wool can be treated with salts formed by tetrazotising benzidine, o-dianisidine and 4,4′-diaminostilbene. Evidence is provided that the salts react with aromatic nuclei present in certain amino acids that form part of the keratinous molecular structure of wool, to form in situ azo dyes. Details of the process and a number of potential practical advantages are discussed