Ruskin Design – Introduction To The Tanning & Finishing Process Of Leather


A successful leather re-trim not only depends on the tools, design skills and the production team to delight the owners. It also depends to a large extent on the ability of the designer and trimmer to identify the type and the condition of the leather to be worked with.

Leather is the outer skin of an animal. Which tanning into a flexible sheet has preserved. The process of tanning an animal’s skin was a well-kept secret handed down from father to son. That is until more recent times, when modern manufacturing processes have demanded speedier and faster results.

Leather working is one of the oldest industries known to man. The origin of working leather was probably started shortly after the first cave dwellers set down their plates after their first meal. Man’s ability to adapt to survive by using this waste by-product of his diet, undoubtedly enabled him to develop faster than any other creature on earth.

He used the animal’s skin as a secondary covering to keep him warm. For strapping that enabled him to carry things and still use his hands.  For example a gourd for transferring water using a sling or a weapon adapted to kill his food. It effectively changed the way he lived, in saving him energy that was previously used hunting his prey.

As man developed through the ages, so did the use of leather. From the original use of weaponry of the cave man to what it has evolved into today – a fashion accessory. Whether that be shoes, jackets or handbags or the sofas that we stretch out on at the end of a long day. Or more importantly to us, the suppliers of the finest leather vehicle interiors, oozing quality.

To get a better understanding of this natural product, the expert designer or trimmer must consider all the events in an animal’s life leading up to the point of slaughter.

For example, what country did the animal originate from? Was the climate hot or cold? Was the climate Wet or Dry? Is there evidence Insect infestation or disease? Was there enough natural forage for the beast to graze on? These can all affect the final condition of the hide.

These are all questions that a designer or trimmer needs to know the answers to. The answer to these questions will help decide the suitability of a particular type of leather for the intended use. Professional car trimmers will want the best-graded leather for strength, look and feel of the finished product. The hide from an animal living in a hot climate is subject to more flaws from insect bits etc. Animals that are fenced tend to suffer more skin injuries than free range animals. Animal feed can affect elasticity, durability and longevity. Older animals tend to have more defects in the skin and require more work in the tannery to make it supple.

The Tanning Process

There are two main steps completed during a tanning process. The first is the raw tanning and the second is the finishing.


The tanning process starts when the skins are in their raw state. When they are first delivered to the tannery. The tanner then looks at several aspects of the hide, the overall condition, its size, thickness and the extent of any damage. Once a hide has gone through this selection, it is thoroughly washed and immersed in a chemical vat or bath for a period of time. This process removes all hair from the skin and neutralises any traces of salt. The edges are then trimmed to remove any peripheral damage.

The next stage of the Tanning process is where the hide is cut laterally through to pre-determined thickness. A very accurate machine is employed to cut through this hide to produce on average four sheets or layers, each of equal thickness.

For designer clothes, shoes and accessories. Thinner layers would be used, as it has been known for a hide to split between 12 and 18 times. However it’s usually only 3 or 4 times for furniture and vehicle interiors. It is important for the trimmer to recognise these layers in their finished state. An understanding of where they could or shouldn’t be used in vehicle interiors is very important.

The first layer is the Napa or Grain split, this retains the entire original graining features. These are also the toughest types of leathers. They are the outside of the hide and have obviously been weathered for the duration of the animal’s lifetime. This is why Napa hides are always used in the manufacture of high quality goods. With the least amount of processing required on a Napa hide, the higher its commercial value. The second and third layers are called ‘The Splits’. These Splits are used to produce Suede or corrected Grain pigmented hides.


Having been dyed, the hides are stretched on to frames and rehydrated in humidification chambers. The hides are then allowed to rest for a period of time.

The hides are then re-selected for the intended use of the hide. The lesser quality Napa hides will receive a covering pigment coat. The top quality Napa hides will be used for a natural leather finish.  Featureless splits will become Nubuck or Suede and a choice of grain will be applied to make the surface look uniform.

Leather Type Identification

Not all finished leather is suitable for car interiors.


Aniline Leather is a top quality. It is natural leather in which the actual surface grain markings of the true leather may be visible. Aniline leather has little or no protective treatments applied. Natural leathers can be classified as Natural, Pure and Un-protected.

Usually, they are coloured with a transparent dye. With a variety of clear finishes such as oil, wax, nitrocellulose and urethane protecting coatings to add a finish that allow the natural leather to show through. These do not inhibit the softness or the breathing of the leather.

Due to its porous nature Aniline leather requires different cleaning procedures compared to a protected pigmented leather. This is because it’s prone to sun fading, which makes aniline leather unsuitable for vehicle car interiors.

Identifying the characteristics of Aniline Leather is very easy. Scratches and water drops are used to do this where leathers will darken and dry back to their natural colour.

Pigmented – Protected – Top Coated – Painted Leather

This is the most common type of leather used in vehicle interiors. It takes up a high percentage of the market. This type of leather has an intense colour and a definite pattern (grain). You can see very little natural leather markings through the top coatings. This is because a pigmented leather paint coat is applied to the surface and then sealed with a durable finish. Proper care will ensure the finish will last for years.

Identifying the characteristics – This leather will have uniform colours and grain patterns, will not scratch easy and the water drops will not change the colour of the leather because it does not penetrate through the surface.

Nubuck or Suede

Nubuck is natural Aniline leather that has been surface brushed or buffed on the “grain” side of the leather. This action creates a nap and leaves a texture similar to velvet. Usually Nubuck has a natural finish, but in some cases it may have a light protective coat and a transparent leather dye for colour. This process increases the leather’s surface exposure making it extremely absorbent to body oils and soil, which is difficult to clean effectively, which makes this leather finish also unsuitable for vehicle interiors.

Identifying characteristics – very soft to the touch. Will scratch and scuff very early. Water drops will darken the leather but they will return to the natural colour once it has dried.