Leather is a material acquired by tanning the skins of animals (cowhide, calfskin, goatskin, sheepskin, buffalo skin, etc.). Creating leather is a complex and highly elaborates process carried out in various steps.
Leather has been used for the most varied clothing and other items since time immemorial and has spread into ever-growing areas of application and is enjoying ever-growing popularity. Even prehistoric man was able to use primitive methods to prepare animal skins and pelts for his needs, for example, housing or clothing. Tanning is frequently described as the second-oldest profession in the world. Even today, leather remains a permanent feature of our everyday lives. Hundreds of thousands of skins are constantly being transformed into shoes, jackets, couches, purses and car seats. The leather itself originates from Europe, South America, India and even from Africa and other regions.
To stop the organic decomposition and to prevent qualitative damage, the raw materials must be preserved as quickly as possible. This is normally carried out using salt. In regions where distances and existing supply chains permit, the skins are preserved through short-term refrigeration, hence dispensing with salt. In some regions where salt is in scarce supply and the climate permits, the skins and pelts are dried.
To prepare the skin for tanning, it is sent through the so-called “water workshop”, where, among other things, non-leather producing components (hair, subcutaneous tissue, fat and unstructured proteins) are removed. This is carried out chemically in the soak pit, during “liming”, for skin digestion and with mechanical processes (fleshing, splitting and setting). Following this, the resulting “naked skins” are ready for the actual tanning process. Tanning can be carried out using vegetable tanning substances or minerals. In the case of vegetable tanning (bark tanning), oak or spruce bark, extracts from quebracho, chestnut and oak woods, mimosa, sumac and other woods or bark tanning substances are used. In the case of mineral tanning, we distinguish between chrome (chrome tanning) and alum (taw tanning).
The tanning process comprises three phases: the soaking of the collagen, the immersion of the tanning extract and the fixing thereof.