Oak and spruce bark from younger trees are used, because they contain more tannin. There are around 300 different plant species worldwide, which can be used for tanning. Other plants contain more tannins when they are younger. Many plants used for leather tanning require up to 30 years growth, to allow sufficient amounts of tannins to be produced. The taste of red wine is fundamentally influenced by the type of tannins and their concentration. In food, tannins are perceived as dry, rough and furry. In addition to the plants mentioned above, tannins are also contained in wine, chestnuts, hops, sumac and black and green tea. Tannins are found in varying concentrations in different plants. Plants store these as a defence mechanism to ward off attacks from potential predators whose digestion is adversely affected upon consumption. Vegetable tanning is based on tannins (polyphenols and gallic acid) which are found naturally in plant species. In particular, vegetable tanning agents are better absorbed by leather and therefore fill it better, are therefore heavier and can be better processed into firm leather. Leather can consist of up to 45% tanning agents. Due to their excellent shape retention, vegetable-tanned leather can be moulded, carved and embossed very well. Today only thick and firm leather is vegetable-tanned. Since plant tanning dominated long before chrome tanning, in particular old leather is mostly vegetable-tanned.
In the niche where vegetable tanned leather is superior to other tanning methods, or where leather lovers prefer this natural tanning agent, vegetable tanned leather is strong and will continue to have its place.Ī campaign by the Italian leather industry for vegetable tanned leather ( Vegetable-tanned leather is usually recognized by the brown colouration.
Before chrome tanning, tanning with vegetable tanning agents was the dominant tanning method. The cost and quality advantages of chrome-tanned leather have reduced the proportion of vegetable-tanned leather to a niche. Recently, the more modern and industrialised tanning methods have become common and it can be assumed that nowadays only 10 - 12% of all leather is vegetable-tanned. Since the discovery of Ötzi in the ice of the Alps it is evident that several leather types were prepared for various uses even 5,000 years ago. Ornaments placed on stone coffins reveal that vegetable tanning was around in the 4th millennium BC in Egypt. Tanning with plant substances has existed for over 5,000 years and was, for many centuries, the main tanning method. Also the term " natural leather" is used. The tanning agent is then a vegetable tanning agent. Vegetable tanning refers to leather that is tanned with oak bark, spruce bark, quebracho, tara pods, olive leaves, rhubarb roots, mimosa or coffee bean shells in the pit or in the tanning drum. 6 The light fastness of vegetable-tanned leather.
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