Innovation in leather is minimal; after all, it is a natural product. The best leather comes from cattle, preferably from the bull because his skin is nice and tight and even better from a young specimen. Fine pores being the quality criterion. Should you want to breed such a bull purely for his skin then you need a proper diet, good hygiene because excrement impairs the skin’s structure, and smooth fencing. A natural environment with thorny bushes and a lot of insects is inadvisable because this will cause bruised skin which is reflected in the quality of the leather.
After the slaughter the animal is skinned and the skin is soaked. During the soak special ingredients cause the skin to swell. Swelling causes the skin’s structure to open, improving penetration of the tanning agents. At this stage the skin is also referred to as “bare. Meat residue is removed from the skin and used in the cosmetics industry for its collagen. Then the leather is grained; the hair is used in the production of shampoos for its keratin content.
Once swelling has made the skin several centimeters thick, it is split into 2 or more layers in the splitting machine. The top layer with grain is called the grain layer, the bottom layer is called the split.
Now the tanning agents can penetrate the skin and adhere to the skin fibers. Once this process is complete, these agents cannot be removed anymore. The rough skin is now leather, a product that is much less sensitive to temperature and spoiling.
There are several tanning agents, including:
Each tanning agent creates an unique leather type with its unique character and qualities.
Today’s tanning method used most widely is mineral-chrome tanning.
Leather made by the chrome tanning method has a blue-green color and is still wet, which is why it also known as Wet Blue.
Once tanned the leather undergoes neutralizing, follow-up tanning, and greasing steps.
Specific qualities that can be introduced by means of follow-up tanning include:
During dying in the vat the leather gets its color. Then the tanned skin fibers are greased ensuring that once dry the leather fibers can be more easily moved so that the leather receives and retains its smooth grip and feel.
Drying the leather involves more than simply removing moisture. Generally the mote intense the drying process, the harder the leather. Post stretching is used mainly for leather types that must remain smooth, like Nappa leather and leather for upholstery.
Moisturizing or conditioning is followed by coagulating and walking. Coagulating and walking make the leather smooth and supple.
In this intermediate phase the skin is also called crust.
Depending on the intended final use, the leather now gets a coating finish, a semi-aniline finish, or an aniline finish.
Satinizing and Bügeln
During the finish process the leather is subjected to bügeln or satinizing several times. The purpose is to make the finish layers smooth and to make them bond together (create a film) and to seal the leather. During bügeln (ironing in German) a roller is used to roll over the leather at a specific pressure and temperature. The purpose of satinizing is to make the leather smoother and give it a finer tactile structure.
By means of etching the leather can be fitted with a certain surface structure. Examples of etching are the so-called hair grain, resembling the grain structure of the skin. Etchings are mostly used on abraded leather types. Imprinting can also be used to make the skin resemble a different skin type, for instance crocodile or bison skin.
Countries famous for their tanning industry include Italy, Spain, England, France, Turkey, Morocco, India and Pakistan whereby China is a major emerging player. In countries like India, Pakistan and China working conditions are abominable and environmental protection measures minimal. In Europe the tanning industries come under very strict environmental protection regimes which results in a more expensive product. Consequently the number of tanning facilities in the Netherlands has decreased strongly.
The quality of the leather depends on the quality of the skins and the craftsmanship of the tanner.
The skins: sheep grazing fine English meadows will provide better skins than sheep in countries like Syria or Australia where they suffer much more from thorns, insects etc. Italian tanners are capable of making top quality leather from even moderate quality skins. The English tanning industry has lost much ground because they persisted too long in outdated methods. France and Spain produce good quality leather. Sweden produces mainly leather for upholstery. Countries like India, Pakistan and China mainly produce cheap leather, something that proves quite competitive for the traditional leather producing countries.