What is tanning?

Transforming the hairy skin of an animal into a product in which you can feel completely comfortable is no simple matter. Tanning is actually a fairly complex chemical process in which tanning materials and tanning auxiliaries are used to inter-link the protein fibers in the hide or skin. This turns the vulnerable, perishable skin into a putrifaction and water resistant , supple material that retains its shape when made into articles, yet conforms to the individual shape of the users e.g., foot.

People have known how to tan hides and skins since the dawn of civilization. However, the job of the tanner or "leather-maker" was not easy. The first problem was removing the hair from the skin. The simplest method was just to let it rot away, and indeed this was the technique used by many tanners for a long time. Other, more progressive tanners used lime for unhairing. This was not exactly ideal, however, as the skins then had to be delimed to remove the lime. Bating was also carried out to soften the skin and this involved treating the skin with animal dung!  - a not altogether pleasant task!

 

Then followed the actual tannage. Enlightened representatives of the early leather-producing, Colleagues who were still somewhat suspicious of chemistry, placed the skins in a pit filled with tannin-containing tree barks, fruits and leaves and left them there for a couple of years. Others immersed the skins in drums of cod oil and then hung them up outside to dry. In view of the resultant "emissions", as we would call them today, it is no wonder that tanners were not the most popular people around. They tended not to live very long, either. Many of them died young as a result of handling obscure toxic substances or from fatal infections contracted in the course of their work.
 
Thanks to modern chemistry, tannage today is a far cry from the smelly trade it was in the Middle Ages. The methods used nowadays are somewhat more sophisticated, e.g. enzymes are used for unhairing. Chemical companies offer a vast range of products that have transformed tanning into a modern, clean and respected trade.

Chrome tannage is by far the most important tanning method used in the production of shoe upper, furniture upholstery and clothing leather, as it is suitable for nearly all types of leather. Chrome-tanned leather has special advantages:

• it has outstanding dyeing properties
• is extremely light fast and has high mechanical strength
• production times are short and tanning material costs low

Old pit tannage also still exists in principle - although in a less aggressive form, of course, and carried out in modern plants. In vegetable tannage, the skins are treated with vegetable, or at least non-mineral, tanning materials by the counter-current process. This yields hard wearing leathers suitable, for example, for shoe soles, saddles and furniture which have to withstand a lot of wear and tear.