Tanning hides has an environmental role that is often overlooked. And yet it enables a by-product of the food industry to be recovered and made into something special instead of ending up as another waste product for disposal.
An age-old art
Leather-making is one of the most ancient of human activities: indeed, we have always used the animals that we have hunted and bred to obtain clothing or shelter. In the early days, though, temperature posed a problem, as the hides tended to rot in the heat and stiffen in the cold. A way of preserving them was needed. Fats began to be used, most probably, to lend greater strength and flexibility. Smoking and tanning with aldehyde – derived from the fumes of burned foliage – certainly developed into widely used techniques, but it soon became clear that the best results were achieved with curing. Over time, the procedure became increasingly sophisticated, and different techniques developed in different places: alum tanning, for example, became established in volcanic areas, while vegetable tanning with tannin took root near oak woodlands.
From the middle ages to modern times
During the 8th century, under Moorish rule, the Spaniards developed leather production, which became famous throughout Europe as cordovan. Leather-working skill, however, was not the exclusive prerogative of the western world: in “The Million”, Marco Polo recounted how the Mongols used flasks, blankets, masks and caps made of leather, often finely decorated. Later, around the 12th century, the depilatory effect of quicklime brought such an improvement in the tanning process that no major changes ensued until the next century. Nonetheless, two innovations worth mentioning, which speeded up the process considerably and were applied in industrial production too, were the use of chromium salts and the replacement of the traditional vats with rotating drums, besides the discovery of new types of tannins.