Slide toggle

Skin

The skin in its original state is difficult to use because it undergoes the process of putrefaction and is sensitive to temperature variations. The tanning has the purpose of safeguarding the skin preserving its main characteristics: resistance, elasticity, impermeability, softness.
The working process can be applied to all the animal skins (mammals, reptiles, amphibians, fishes, birds), obviously the most widespread is the skin of the mammals from which it derives leather and furs.

 

SKIN STRUCTURE

The skin of each species is formed by three main layers: epidermis, dermis, and subcutaneous layer. The epidermis represents 1% of the skin, it is the outermost layer in which the corneas formations are found (hairs, scales, nails and horns) and glandular (sebaceous and sweat). This part is generally discarded by the tanning process.

The dermis constitutes 85% of the thickness of the skin, and is the area affected by the tanning. It is distinguished in two layers, the papillary layer, in contact with the epidermis, is called “flower” is a ¼ of the thickness of the dermis, here the collagen fibers are more compact; the underlying part is the reticular layer called “crust”.
The subcutaneous or adipose state, is 14% of the skin; it is the residual tissue not removed during the skinning phase containing a high quantity of grease. In the initial stages of tanning, this layer is definitively eliminated.
The dermis is the layer that is worked in the tanning process, it is the part that has commercial value. The qualitative level is indicated by the density of the fibrous fabric which determines its resistance and elasticity, by the thickness, the homogeneity and the appearance of the grain.

CUT SECTION

Depending on the thickness, the various areas of the animal’s body are dissected: the “butt” is the thickest part and therefore the most precious, its fibrous structure is more uniform and constitutes the largest surface of the mantle; the “sides” are less thick and the structure is weaker while the “shoulders” have the same thickness as the rump but the fibers are less strong.

Quality is closely linked to provenance, weight and age. Origin is a fundamental element for quality assessment; livestock reared in the mountains provides better skin than livestock raised in the plains, and livestock raised in the free state (semi-wild) also hides skins with higher physical qualities (weight, thickness, density of fibrous tissue) than livestock reared with a stallion ( cattle breeding). The feeding of cattle destined for slaughter, produces a thick but loose skin, while the working cattle leaves the skin with a consistent and tenacious skin. The weight affects the thickness and density of the fibrous tissue of the skin; in the trade all the skins are treated according to their weight.

TYPE OF SKIN

A further classification to determine the quality of the skin can be made based on the breed of the animal:
– Bovine hides or veal skins: ox, cow, bull and calf
The ox, or the castrated male provides heavy leather, while the cow lighter and thinner skin, the bull is obtained a heavy skin and is usually treated with tanning to tannins (vegetable compounds used in tanning to preserve the nature of the skin they give characteristics of uniqueness to the material), the shot, young bovine no longer calf, is characterized by a soft leather often intended for the realization of the uppers, finally the calf has a very fine leather and is entrusted to the most valuable works.

– Goat skins: goat and kid
The quality of this category depends on the grain, which can be fine or coarse; excellent material for every type of leather, it is worked above all with chrome tanning.

– Sheep skin: sheep, mutton and lamb
This group offers a greater supply of leather to the detriment of quality. They are classified according to the type of wool: fine wool, the hides are poor and spongy for a cheap leather lining, half-fine wool, leathers of English origin are wider and thicker for a strong and quality leather, rough wool, leathers with medium size and uniform fabric, they offer superior quality, thick, fine-grained dog hair and provide full leather.

The skin must be pretreated before being tanned by three steps: slaughtering, skinning and storage.
The animal is cut down by limiting its suffering and keeping the value of the leather intact. In general, the animals come from meat-producing companies so the skin must be pretreated in order not to decompose during transport, therefore after the killing and bleeding takes place the skin. Finally we proceed to the conservation phase which involves the dehydration of the skin by introducing salt to prevent rotting and to maintain intact the qualitative characteristics of the skin.