Posté le 27/11/2014 à 14:07:24            

How is leather produced?

Leather is produced by transforming animal skin. The younger the animal, the better the
quality of the skin, for it will have been subject to less damage (scratching, parasites, etc.).
Tanners use chemicals and mechanical processes to produce finished leathers with various appearances and properties.

THE STORY OF LEATHER

Leather is mainly obtained from the following animals: cattle, sheep, goats, pigs, horses, reptiles, fishes and birds.

The structure of the hide

 The three types of finishing

Aniline finishing emphasises the natural appearance of the leather surface by coating it with a transparent product: fine-looking aspectrequires to be properly cared for.

Semi-aniline finishing covers the leather
surface with layers of slightly opaque pigments which are themselves covered with a transparent film.

Pigment finishing (pigment coat) covers the leather surface with layers of opaque pigments that colour it. High degree of water and stain resistance. Easy-care material.

Flaying and preservation 

At the slaughterhouse, the hide is separated from the carcass of the animal manually or removed mechanically. This operation is critical and requires skilled labour, so as to preserve the hide’s qualities.

Each hide is classified according to its qualities
and defects. At this stage, it is called a "green hide".

To ensure its preservation, the hide is salted or dried. At this stage, it is called a "raw hide".

 Beamhouse

The soaking process consists in rehydrating salted or dried hides and eliminating preserving agents and impurities. The unhairing and liming processes eliminate, chemically, hairs and the epidermis through scudding or rinsing.

The fleshing process mechanically eliminates fat and flesh residues.

Deliming is the last beamhouse operation: it prepares the skin for tanning by neutralization.

 Tanning

The tanning operation transforms the hide into leather by treating it with tanning agents (tannins) that make it rot-proof.

Tanning agent: chrome tanning salts or vegetable tannins provide the leather with specific qualities..

The leather, that has simply been tanned, is sorted according to its qualities and defects. At this stage, it may already be marketed.

 Dressing and Finishing

The dressing and finishing operations transform tanned leather into finished leather.
Equal thickness is obtained by splitting the leather into two layers: the grain (upper side) and the split (flesh side).

The leather is shaved to adjust the thickness of
the grains and splits more accurately.

Retannage, dyeing and fat liquoring give the leather its colour, feel and softness.

After samming the leather is stretched in the setting-out process.

The leather is dried by circulating hot air in dryers, using paste drying or vacuum drying.

The staking process is designed to soften the dried leather.

Buffing is used to obtain different types of leather: nubuck, suede, or corrected grain.

The leather is finished in one of two operations, either spraying or padding.

Hot plating consists in smoothing the surface of leather by subjecting it to high pressure against a heated and polished plate.

Embossing creates a raised design on a leather surface, imitating the skin of certain animals (e.g. reptiles) or the original appearance of the skin.

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"The story of leather"

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