Image copyright: LCK_Gmelich
|First, the skin must be washed and freed from manure and impurities. Then the skin is "washed". This removes the hair and loosens the collagen structure of the skin.|
The flesh, fat and connective tissue remnants are scraped off. This job is performed by a special "fleshing machine".
In various work steps, the skin is now made receptive for the actual tanning through different processes such as deliming, pickling and pickling.
Only now does the actual tanning take place, i.e. the transformation of the hitherto raw hide into durable leather. Depending on the method (vegetable / mineral / synthetic tanning), the hide is treated with appropriate tanning agents.
In vegetable tanning, for example, tanning agents from oak bark, mimosa or fruits are used. Mineral tanning mainly uses chromium salts or aluminum salts. Today, the tanning process is carried out in large rotating drums or barrels.
The tanned and pressed leather is then subjected to a few final operations. It is split (if it is too thick), nicely dyed and greased. During dyeing in the barrel, soluble dyes bind firmly to the leather structure and thus penetrate the leather completely.
Now the leather must be well dried, after which it will feel quite stiff. To achieve the desired suppleness, the leather is softened by mechanical processing ("milling and studding"). In the past, the leathers were still "softened" by hand, but fortunately today this work is done by special machines and mill drums.
In the last step, the leather is dressed according to its use. In this process, the leather is given some more durable properties, pleasant appearance features and special (fashionable) effects. The leather surface is cleverly corrected so that any damaged areas such as scars are nicely concealed. For example, in the case of defective leathers, a thick additional layer of dye is applied and then the leather structure is applied with an embossing roller (since the original skin structure has disappeared under the dye layer).
Finally, the surface thus "tuned" is fixed with a water and stain repellent protection. Finishing thus includes all measures that make the leather interesting for further industrial processing.