Leather Production Processes

The leather manufacturing process is divided into 3 fundamental sub-processes: preparatory stages, tanning and crusting. All true leathers will undergo these sub-processes.

The preparatory stages are when the hide/skin is prepared for tanning. Preparatory stages may include: preservation, soaking, liming, unhairing, fleshing, splitting, reliming, deliming, bating, degreasing, frizing, bleaching, pickling and depickling.

Tanning is the process converts the protein of the raw hide or skin into a stable material which will not putrefy and is suitable for a wide variety of end applications. The most commonly used tanning material is chromium, which leaves the leather once tanned a pale blue colour (due to the chromium), this product is commonly called “wet blue”.

Crusting is when the hide/skin is thinned, retanned and lubricated. Often a coloring operation is included in the crusting sub-process. The chemicals added during crusting have to be fixed in place. The culmination of the crusting sub-process is the drying and softening operations. Crusting may include the following operations: wetting back, sammying, splitting, shaving, rechroming, neutralisation, retanning, dyeing, fatliquoring, filling, stuffing, stripping, whitening, fixation, setting, drying, conditioning, milling, staking and buffing.

For some leathers a surface coating is applied. Tanners refer to this as finishing. Finishing operations may include: oiling, brushing, padding, impregnation, buffing, spraying, roller coating, curtain coating, polishing, plating, embossing, ironing, ironing/combing(for hair-on) and glazing.

Leather Types

In general, leather is sold in three forms:

Full-Grain leather or Top-Grain refers to hides that have not been sanded, buffed or snuffed(otherwise known as Corrected) in order to remove imperfections on the surface of the hide. Only the hair has been removed from the epidermis. The grain remains in its natural state which will allow the best fiber strength, resulting in greater durability. The natural grain also has natural breathability, resulting in greater comfort for clothing. Full grain leathers can mainly be bought as two finish types: aniline and semi-aniline.

Corrected-Grain leather is any Top-Grain leather that has had its surfaces sanded, buffed or snuffed in order to remove any imperfection on the surface due to insect bites, healed scars or brands. Most Correct leather is used to make Pigmented leather as the solid pigment helps hide the corrections or imperfections. Corrected grain leathers can mainly be bought as two finish types: semi-aniline and pigmented.

Split leather is leather that is created from the fibrous part of the hide left once the Top-Grain of the raw hide has been separated from the hide. During the splitting operation the grain and drop split are separated. Splits can are also used to create Suede.

The International Union of Leather Technologists and Chemist Societies has a full glossary of leather terms that can be found at IULTCS

What is leather?

Leather is a material created through the tanning of hides and skins of, primarily cattlehide. The tanning process converts the putrescible skin into a durable, long-lasting and versatile natural material for various uses.