The Art of tanning

What is tanning ?

Making leather is a complex age-old process that recycles raw hides that are a by-product from our food industry. Leather is then used to make sustainable, hard-wearing accessories, tools and garments.

Needless to say, manufacturing techniques have changed significantly since ancient times, with some of the biggest developments taking place in Europe at the end of the 19th century. However, production in ‘dye batches’ remains a sophisticated artisanal process in which man continues to play a major role at every step.

While the industry continues to be modernized, the manufacturing process can be divided into seven main steps that remain unchanged :

  1. Raw hide selection
  2. Retanning & dyeing
  3. Setting & drying
  4. Crusting
  5. Finishing or pigmentation
  6. Quality control of finished products
  7. Measuring, packing and shipping

1. Raw hide selection

Large quantities of crust leathers are delivered to the tannery where they are sorted based on their size, thickness and flaws. Hides are selected based on the client’s intended future use for the finished leather. At this stage, each hide is inspected to identify its differences and specific natural characteristics (hand – from soft to firm -, appearance of the grain, durability etc.) in order to use the available stock as effectively as possible. The selections made ensure optimal use of the hides.  

crust - peaux de chevre

The raw hide tells the animal’s story, and everything that has happened to it in its lifetime.  Because of this, only farms that respect animal welfare and follow proper vaccination practices will guarantee the absence of injuries and skin diseases. Well-organised and dignified culling methods will also guarantee that tanners receive high-quality raw hides.

This initial selection and allocation process is key to ensure hides are suitable for to their intended use: full grain leather, suede, corrected grain, nubuck etc.

The experience, skills and ability of the grader to take risks really shines through, but with the utmost humility.

2. Retanning and dyeing

Depending on the type of finished leather ordered, our team develops suitable retanning formulas and chooses the necessary tannins, oils and fats and dyes.

These formulas, calculated based on the wet leather weight, require a strict protocol with set temperatures, varying rotation times, specific pHs etc. 

le retannage - teinture - Alran

The entire process lasts between 12 and 36 hours, depending on the type of leather.

The hides are soaked in drums which are rotated on their axis to ensure slow mixing. The mass of the hides ensures uniform penetration to the core of the fibres of all hides in the batch.

The dyers’ empirical knowledge of their tools and dyes is evident and ensures that the processes and formulas can be replicated.

3. Setting and drying

Once they are removed from the drums, the soaked hides are placed on wooden trestles for 12 hours to allow the water to slowly drip off. The remaining water is then removed mechanically; this is called “mise au vent” or “setting out”.

The hides are still damp, so they are hung in drying rooms or air dried until they are fully dry.

3 - la seche - la tannerie - alran

4. Crusting

Le corroyage - Alran - notre métier

The leather is now described as ‘struck through’ as the dyes have fully penetrated and colour is therefore uniform on the edges. It can now be refined using machines.

Working with dry or damp hides, depending on the desired result, multiple operations can be carried out to enhance the results of tanning: splitting, polishing, shaving, grain boarding, staking, milling, buffing etc.

Each operation uses a specific machine requiring precise expertise to operate and involving repetitive, finely-tuned techniques that must be adapted to each type of leather. The craftsmen showcase skills they have cultivated over many years. Attention to detail, practical experience and consistency guide their work every day.

5. Finishing

Not all types of leather are concerned by this step. For example, aniline leather does not undergo any surface treatment. This ensures that it preserves its soft, natural feel and appearance, with slight colour variations on the surface.

In the case of pigmented leather, its colour will appear more saturated and intense, and the surface finishes will make the leather waterproof and improve its resistance to stains, rubbing, and fading.

Arnal - cuir de chevre - la finition

Finishes are applied either with a spray gun or roller coater. There are numerous options in terms of glossiness, colour and feel.

This stage highlights the experience of our dye experts and their ability to reproduce a colour from the samples received and recreate the same specific shade, batch after batch.

6. Final grading

Before shipping, a final exhaustive inspection of each hide is necessary, based on the specifications for the product.

These verifications ensure that each hide, from each batch, is checked before leaving the workshop and that quality is assessed objectively based on the evaluation criteria for the leather ordered.

le controle final du cuir - alran

Based on these checks, the hides are sorted into grades. The grade proportions per batch determine the average price per square metre.

The finished product grader will assess each hide based on its hand (soft or firm), thickness, colour (compliant or not, with a predefined margin of tolerance) and all of its flaws (marks, bites, scratches and blemishes etc.).

Feedback given to the rest of the team at this point is key. Sharing useful observations with each team member will allow for continual and gradual improvements in future work.

7. Measuring and packing

Each of the hides is scanned by our optical scanner to determine its exact surface area.

The measurement and grade are printed on the flesh side of each hide, visible whether they are packed rolled or flat, making traceability easier for the recipient artisans.    

Finally, the packages are shipped around the world by our transport partners.

The warehouse workers know the materials and packaging process like the back of their hands and demonstrate great rigour. This guarantees that the leather will be protected during the transport process, whether it remains within France or travels further afield.

expedition alran
notre metier - la tannerie - alran - cuir de chevre
notre metier - la tannerie - alran - cuir
notre metier - la tannerie - alran - cuir de chevre - mazamet
Tannerie Arnal - cuir de chevre - megisserie française

Whether you specialise in book binding, leather wrapping, leather goods, boot or shoemaking, we will work closely with you throughout the entire development process.

We assist and guide stylists, pattern makers and workshops at every step.