Leather is animal skin that is transformed by tanning in a way that preserves its main properties and prevents decay. The main characteristics of genuine leather are: flexibility, toughness, strength, depending on the tanning process more or less impermeable to water with sufficient air and water vapor permeability (sweat), as well as heat insulation and durability.
In the actual tanning process involves many different processes and working methods are edging, the oldest of the Fettgerbung (chamois), then followed by the vegetable tanning process which is already in the 4th Millennium BC, was known to the Egyptians, and the Alaungerbung. 1880, chrome tanning was added and since 1910 the tanning with synthetic tanning agents.
In simple words, are the main method as follows: in the vegetable tanning, the classic tanning method, the rawhide in mines by using tan is very slow, depending on the strength of leather tanned up to two years. The blaze is produced with water from the vegetable tanning agents. Hauptgerbstoffe the Gerbrinden (oak, spruce, willow, mimosa) are Gerbhölzer (oak, chestnut, quebracho), the Gerbfrüchte (Dividivi, Mayrabolane, Valonea) and then the Gerbblätter (sumac, Gambir).
In order to achieve a simplification for the tanner in the vegetable tanning, were since the end of the 19th Century from the tanning extracts recovered and allowed in connection with use of slowly rotating drums Walk a significant abbreviation of the Gerbdauer.
The principal mineral tanning agent is the chromium salt. The chrome tanning takes place in the rotating tanning drums and lasts, depending on the skin for a short time. The synthetic tanning agents are used both as auxiliaries and Austauschgerbstoffe the chrome and vegetable tanning as well as Alleingerbmittel. After the actual tanning process, the rawhide is processed, ie greased stained, dried, and mistaken in the finishing plants with special Narbeffekten.