The tanning

The tanning is the central work process in leather production and is a targeted refinement technology. That is where hides become leather. The tanning agents are the focus of tanning. These are molecules or chemical compounds that can react with the collagen in such a way that stable cross-links are created. The more such cross-links are created, the more stable the new structure of the leather is. About 25 kg of finished leather are produced from 100 kg of raw hide.

 

There are a variety of types of tanning:

  • Tanning with alum (the oldest type of tanning)
  • Tanning with vegetable tanning agents (bark, wood, leaves, roots)
  • Tanning with animal fats
  • Tanning with aldehydes (smoke tanning)
  • Tanning with mineral salts of chrome, aluminum, zirconium, titanium, iron
  • Tanning with synthetic tanning agents
  • Tanning with polymer tanning agents
  • Tanning with fatty tanning agents (Tran)
  • Tanning with reactive tanning agents
  • Tanning with resin tanning agents

Leather is often referred to as a natural product. Tanning with vegetable tanning agents is recognized as "natural" tanning and tanning with chrome tanning agents as "chemical" tanning. The tanning with vegetable tanning agents is presented as environmentally friendly, while the tanning with chrome tanning agents is regarded as polluting. Such arbitrary classifications do not stand up to objective consideration.

The color of the leather after tanning indicates how the leather was tanned:

  • Mineral tanning agents (chrome, aluminum, zirconium): Lightfast, white-blue-gray, flexible, heat-resistant
  • Vegetable tanning: Not lightfast, brown, dimensionally stable, not heat-resistant
  • Synthetic tanning: Lightfast, white-brown, dimensionally stable, not heat-resistant
  • Fat tanning / chamois tanning: Not lightfast, yellow, very soft, absorbent, sweat-resistant

"HSF only offers chrome-tanned leather (chrome III). The tanning process is faster and more material-saving."


Copyright picture: www.leder-info.de
Source: The Gerber - Professional Leather Production (Gerhard E. Moog)

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