Tanning - Profiling the tannery process.
01 February 2021


Recent regulations on environmental management, pressure from certain NGOs, and the demands of luxury firms led us to look at the leather tanning process from a new point of view.



Only ten years ago, the criteria for selecting a product for a certain process was limited to the technical goodness of the product itself, without considering its ultimate consequences.

Today we must approach the tanning process with a new philosophy. For each product we use, we must ask ourselves: What is its composition? Does it contain substances that could be a cause for concern? How is it related to other substances present in the process? Can it degrade generating undesirable emissions? How much does leather is actually retained how much ends up in the effluent? Does it generate high COD / BOD, persistent, recalcitrant substances or eutrophication? How does it affect the bacterial flora of the effluent plant? What contribution of greenhouse gases do I generate during the treatment? Can I reduce the salinity of the process, or treat the salts generated in my effluent plant? What is your LCA? Once finished, what is its behavior in relation to the manufacturing process of the end product? Once the life cycle of leather has been fulfilled, how will the use of this substance influence the biodegradability and compostability of the finished article?

This paradigm shift imposes on us new rules of the game, partly written in good practices (BATs), partly to be defined.

This paper presents an example of analysis of a riverbank process, considering different points of view: health of the process, environmental impact, and technical characteristics of the finished article.


Animal skin is a natural and biodegradable raw material. The traditional process is an example of sustainability and circularity. The leathers and food residues were manually fleshed, and the fats obtained separated and preserved for successive operations or as lubricants. The soaking and peeling process was traditionally enzymatic from its remote origins: both hair and wool were eliminated with methods that go from "heating" (controlled putrefaction process), to the use of residual enzymes from different types of excrement (that of e canines, for example, had the property of waxing hair and epidermis in a few hours). The skins, after being treated in lime, were delimed in torrents and purged with guano or polina (which contain organic acids that solubilize the lime), and other enzymes (for example pancreatic), which made the skins fluffy.

The tanning methods were based on different available products (from urine, unsaturated oils, the brain, different types of tannins, or rock alum), to then grease them with egg yolk, tallow, degras) and finish them with albumin, casein, with unsaturated oils. There are countless traditional processes that show that skins can be treated naturally, without altering the environmental balance.

For example, the process that was carried out in Entrerríos de Antioquia (Colombia) used

natural products (from guano, to barks and fruits, to carry out the tanning of traditional leather goods.

With this process, durable leathers with a very good tanning quality were obtained.

The process times would not make it possible for industrial production (the tanning needed months to go through), but if we consider it from the point of view of sustainability, little can be said against it.

The use of renewable raw materials (barks, guano, fruits), without the need to use energy sources. All the products used (except the lime) came from a few kilometres away in the local environment.

Enter the Chemical Industry

Traditional processes underwent a great transformation during the 20th century when the chemical industry provided technical solutions to reduce process times and convert tannery into


Much of these substances were derived from petroleum. The use of sulphides in hair removal, the sulphation of tannins, substitution tannins, polymers, chrome tanning auxiliary fur, are all creations of the last century, which notably reduced the production times of the leather, but by increasing the impact on the environment.

Read full work here: http://tecnologiadelcuero.aaqtic.org.ar/perfilar-el-proceso-de-la-curtntación-del-futuro-un-cambio-de-paradigma/

Source: Gustavo Adrián Defeo FSLTC Aaqtic for Indumentariaonline

Original URL (in Spanish)

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