How exactly does the skin tanning process develop?


The tanning industry is one of the most appreciated Made in Italy excellences all over the world. Tanning is the processing that exploits the skin, usually of animals raised for food such as cattle, sheep, pigs, making it softer, pleasant to the touch and resistant. At present, tanning is a process carried out by medium and large companies, which can ensure a final product of quality at an affordable cost, thanks also to technological developments that have automated part of the processing.

The entire process is necessary not only for aesthetic purposes, but also to ensure that the skin, given its organic nature, does not undergo decomposition and can maintain its characteristics for a long time.

How the tanning of the leather takes place

Not all processes take place in the same way and the production line to be used is chosen based on what is the desired end product. In general, the entire tanning is divisible into three large phases, each of which is composed of various intermediate processes.

The three main phases are: Riviera processing, Tanning, Finishing.

Separating the skin of the animal, it is kept avoiding rotting and then sent to the tannery where the Rinverdimento takes place: with this method is replenished the natural moisture of the skin, lost during the storage and shipping period.

Calcinaio (name derived from the use of lime hydroxide) is the process that prepares the leather for the absorption of tanning agents and the Depilation provides for the removal of hair, both occur chemically and are followed (in the case of very thick skins) form the rift, which divides the skin into multiple layers through a mechanical action. 

The Scarnitura then takes care of removing the residues of excess fat and the subcutaneous tissues left after the skin of the animal, this process ends the Riviera Processing.

The Descaling removes the lime that has remained attached to the fibers of the skin and, thanks to the acids used in the process, lowers the pH, thus counteracting the increase deriving from the lime hydroxide. Maceration completes the work, relaxing the fibers so as to prepare them for the absorption of tanning substances. Piclaggio uses acids that further reduce pH to 4 and block decomposition.

Finally, the actual tanning can be done using trivalent chromium or vegetable substances (a sector in which the Tuscan Tanning Pole is among the most appreciated) and aims to make the leather more resistant, flexible, waterproof and breathable.

The leather is then pressed to remove excess water and is reconnected again to give the desired degree of softness, often to it are added dyes to dye the leather. The way in which tanning and retanning take place are among the main factors that determine the final quality. Thanks to the addition of oils and fats, we then proceed to Fattening, which serves to preserve the softness of the leather for a long time and makes it more hydrophobic and resistant.

Given the high water content, the leather must then be dried and, a revolt removed excess moisture, it will appear dry and rigid. To avoid this it is passed inside rollers by the wavy surface that “massage” and stretch the fibers, softening them: this process, called Palissonatura, is particularly suitable for leather that will be used for accessories, gloves, belts, whose processing also requires a certain degree of flexibility.Finally, the skin is ground with abrasive rollers to remove any residue from the inside and get effects like Nabuk. This step also allows you to remove some imperfections, filling the flower and then deburring the surface.

The last steps are those of the Finishing, which consists of a painting that can take place by spraying with airbrushes, by spreading a layer of paint or dabbing the skin, often by hand, with a sponge soaked in paint. Different types of finishing result in different aesthetic results. Finally, a step under the rollers can create special effects such as leopard print or python, applying an adhesive paper to the leather surface.

Finally, trimming (cutting) and surface and thickness measurement complete the entire tanning process.

A valuable result

This series of complicated chemical reactions and mechanical processes is able to give nobility to products that, in fact, are often nothing more than slaughtering waste. The methods used today are the result of centuries of technological development that has meant an incredible increase in the quality of the final product, which allows the creation of pieces of craftsmanship of spectacular quality. Leather manufacturing is a historical sector of Made in Italy and a source of pride all over the world, cities like Florence are its undisputed homeland. Although long and complicated, sometimes bloody, leather tanning has now reached very high production levels and allows you to use those that would otherwise be wasted resources, giving raw leather a future made luxury and exclusivity.