Leather processing cycle: initial phase

The leather processing cycle is one of the oldest examples of recovery and enhancement of a by-product. In fact, since prehistoric times, man realized that he could use the skin of the animals he hunted to cover himself.
Just as then, the leathers used by the tanning industry are a recovery of the food industry. This involves recycling and finishing a product that would otherwise be disposed of as waste with the consequent environmental cost.

The leather processing cycle can be considered a real art, which involves a series of transformation steps that lead from fresh leather to the finished product. Below and in the next articles, we will try to give you more information, to help you better understand the various stages of processing.

⇒ The initial product is fresh leather which is subjected to the first preservation treatments through drying or salting.

⇒ In this way, the raw leather is obtained on which the treatments that precede the actual tanning begin and prepare the leather to receive the tanning substances. These treatments make it possible to eliminate dirt and any meat residues through the use of special machines and washing with water and specific chemical products. Furthermore, through the use of lime and other chemical solutions, they favor the opening and relaxation of the dermal tissue making it more absorbent. And finally they allow to block the maceration process, through the use of acids and salt, bringing the leather to a PH suitable for the subsequent tanning phase and thus transforming it into pickled leather.

⇒ At this point we enter the tanning phase, which is the step in which the leather irreversibly stabilizes, giving it the typical characteristics of resistance and durability. The types of tanning are distinguished based on the tanning agent used, which can be inorganic (mineral tanning) or organic (tanning with tannins, oil, …). In our case, the leathers we work with have a chrome and therefore inorganic tanning, from which the so-called Wet Blue is obtained.
Chrome tanning is the most used for its ability to create very stable bonds with the collagen structure of the leathers. The type of chromium used in leathers is defined as an essential oligonutrient, which also finds application in other sectors such as steel and fabrics.

But what are the advantages of chrome tanning?

• greater thermal stability

• greater water resistance

• takes less time to process

• the fibers subjected to this treatment show very satisfactory elasticity and tensile strength

• guarantees the highest resistance to hydrolytic attack by acids and bacteria

• possibility of recovering trivalent chromium from exhausted baths

Having reached the Wet Blue phase, we have a material that is no longer putrescible ready for specific transformations based on the type of final product to be made.

Did we stimulate a bit of curiosity?
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