THE CHALLENGE OF MANUFACTURING LEATHER DYES TODAY

The introduction in July 1994 by the German parliament of an amendment to their Consumer Goods Act, which prohibited certain azo dyes, has h ad consequences world-wide at all levels of the leather industry. The general thrust behind the law has strong support at all levels in the industry but the fine details have caught many unaware of their practi cal implications. The German law makers have found they needed several further amendments to bring even some degree of workability to the le gislation. The test institutes world-wide have discovered an exceeding ly lucrative new business niche in chemical analyses. Those in the lea ther manufacturing chain, from tanners all over the world through to t he German retail shops, have faced frustration. They have been struggl ing to come to grips with the practicalities of a law that was introdu ced without a valid test method to enforce it. At the other end of the chain the azo dye manufacturers have had to subject their products to analytical scrutiny at the parts per million level and have discovere d the limits of analytical methods. The German Act prohibits the use o f certain azo dyes in defined consumer goods that come into repeated c ontact with the skin. The azo dyes affected by this legislation are th ose that after splitting up of the dye molecule at the azo groups rele ase any of the 20 amines listed in the Act. Those involved in developi ng the analytical method quickly discovered it is easy to legally defi ne this splitting up of dye molecules, but in practice much more diffi cult to implement so that only amines from the splitting of the azo gr oup were detected. Dye molecules are happy to split in other ways if t he: reaction conditions are sufficient. Any type of correlation with t he real life in vivo reduction reactions was never considered as the a nalysts struggled within strict time constraints to produce a German s tandard test method. The manufacture of a dye today, taking into accou nt all the constraints of the above legislation, can lead to ''clean'' dyes being labelled as doubtful. The manufacturing process of a dye w ill be followed to show how such a situation could arise. it is clear that there are still areas of greyness in the Act as it stands, but th e rapid expansion of this type of legislation within Europe means that all in the leather industry will have to work with the current politi cal, commercial and analytical compromise situation.