Modern tanning chemistry

The range of chemistries used for tanning leather is reviewed; traditional methods of tanning are explained and the newer processes are described. The areas of tanning include: vegetable tanning with plant polyphenols, mineral tanning with metal salts, in particular chromium(III), oil and aldehyde tannages, synthetic tanning agents and organic tannages based on natural polyphenols or synthetic organic oligomers. The fundamental nature of the tanning reaction and the origin of hydrothermal stability are discussed.