A distinction is made between plant-tanned and chrome-tanned leather.
Plant tanned leather
This is the name given to leather that is tanned exclusively with vegetable substances.
Nowadays, only 10-12% of all leather is produced with plant tanning.
Oak and spruce bark, rhubarb roots, tara pods, olive leaves or chestnuts are used to tann the leather. The tanning agents of these plant species are called tannins.
With plant tanning, it can take 20-30 months for the hides to go through the entire process. Tanning with vegetable based products is more expensive than tanning with chromium. To tann a single hide you need up to 30 kg of bark or 20 kg of fruit or 90 kg of oak wood For this purpose, the hides are stored in pits or barrels, during which the tanning agent concentration is gradually increased.
Advantages of plant-tanned leather over chrome-tanned leather:
- less environmental impact during production
- no pollutant emission to humans, therefore also suitable for allergy sufferers
Chrome tanned leather
About 85 % of the worldwide leather demand is tanned with chrome salts. The advantage to vegetable tanned leather is that it has twice the tensile strength. It is also more lightweight, because chromium salts do not saturate the hide. The tanning process is also faster and more economical.
Chrome tanned leather usually does not cause allergic reactions. Only 0.5 of the population has a chromium allergy and should consider vegetable tanned leather.
Chromium tanning produces waste materials, but in modern tanneries these can be minimized up to 97 %.
Advantages of chrome tanned leather over vegetable tanned leather:
- Twice the tensile strength.
- Lighter and softer leather
- More cost-effective in manufacturing, therefore cheaper
In the next posts we will report on other interesting aspects of leather, for example exciting new leather types among vegetable leathers, especially rhubarb and olive leather. There will also be interviews with leather manufacturers who work sustainably. So stay tuned!