The steps in transforming cow skins into leather briefly are as follows:

Trimming – scraggy pieces of skin are cut off and used for glue making or other purposes.

Soaking – removes salt and other solids, and to restore moisture lost when the skins are first dried.

Fleshing - the flesh side of the wet skins are scraped to remove any remaining traces of flesh or fat.

DeHairing – the skins are soaked in a solution and the grain side scraped to remove any hair or hair roots from the follicles. The most common solution used is lime, but other methods are sometimes used.

Bating and Pickling – this is the process of neutralising the lime by the use of enzymes to prepare the skins for tanning.

Tanning – is the process of preserving the skins by soaking them in a bath for a period of time. Tanning is carried out by using either vegetable chemicals derived from the bark of certain trees or by the use of chromium salts. Chromium tanning is by far the most widely used method around the world, since it is much quicker than vegetable tanning.

Splitting and Shaving - the outer surface of the animal’s hide is separated from the lower layers by slicing it with a long knife as the hide is fed through a series of rollers, and the resultant layers then shaved to a uniform thickness.

Re-tanning and Dyeing - after splitting skins generally are re-tanned and simultaneously coloured. Aniline dyes (transparent dyes made from extracts of coal tar) in various colours may be added to the tanning drums at this stage, while the hide is absorbent. If correctly done, aniline dyes are permanent and will not rub off or “crock” after the leather is in use. Dyeing should not be confused with pigmentation or adding colour to the surface of the skin.

Conditioning or fatliquoring - is the process of replacing natural oils that have been unavoidably removed in the earlier steps, and make the leather suppler. This is an important step in tanning leather because without these natural oils, the hides will not have the same strength and flexibility.

Drying – moisture is removed from the hides by a number of methods including vacuum drying or air drying. During the drying process, the hide is stretched to remove wrinkles and create an even surface. Once the leather has been stretched and dried, it is returned to a soft, supple state by tumbling in a large drum and/or working by hand.

Finishing - After drying, leathers can be finished in a number of ways depending on the quality of the leather, the intended final use of the leather, and the desired look and feel of the finished product.

Some of the most common methods of finishing leather are:

Machine finishing - may be any one or more of a number of processes to give the desired colour or texture to the end product.

Leather may be embossed with an artificial grain to resemble the skin of a totally different animal or reptile, or to restore a full grain look to the leather. An even colouration is achieved by a series of finish coats applied by a spraying machine. When the desired colour has been achieved, a clear protective coating is applied to resist moisture and stains. The sheen of this coating can be adjusted to give a high gloss, satin or matte surface. Machine finishing is one of the least expensive and most common methods used to finish upholstery leather. It provides as durable and lasting a finish as any finishing method available.

Hand finishing and antiquing - is the same process as machine finishing except the final colour application is rubbed into the leather by hand. This technique is used to bring out the natural markings in the hide, such as healed scars and barbed wire nicks, and gives the leather a highlighting which can’t be achieved by machine spraying. Hand antiqued leathers are generally more expensive than machine sprayed.

back to Our Fine Fabrics and Leathers