The Secret of Vegetable Tanning Isn't (Just) Tannin

A legend has been passed down through the tanning industry: thousands of years ago, in prehistoric times, an animal ended its life in a rainwater pool surrounded by a chestnut forest. That water, infused with substances we now call tannins, naturally found in bark and wood, worked its first miracle: it managed to stop the deterioration process of the animal’s hide. This is how vegetable tanning was born, and it remains today the most natural method for treating leather, making it sensitive to the passage of time while preserving durability and resistance.

Tannins are found within the fibres of wood, bark and pods. The most commonly used in tanning are chestnut, mimosa, tara and quebracho, which are blended according to recipes that form the foundation of each tannery’s original products. Yet, as Giorgio Tempesti of Conceria Tempesti, a company specialising in vegetable tanning for 80 years, explains, this is not the only element that makes leather unique.

«One of the fundamental stages that makes our company unique is fatliquoring, which is essential in vegetable tanning.» There is the traditional fatliquoring process used for classic vegetable-tanned leather, carried out with beef tallow and other animal-derived oils. This method remains the closest to a 100% natural tanning process and allows the creation of a material that develops unique characteristics over time.

It is leather with a memory: it carries the marks of those who wear and experience it, changing according to the environmental conditions it encounters and the way it is used by its owner. However, in recent years, vegetable tanning has developed new formulations capable of achieving even higher performance levels.

«Classic vegetable leather treated with animal oils remains one of our cornerstones, but we also have a range of products treated with more modern formulations, allowing us to expand our colour palette with lighter and cooler shades, while also improving the adhesion of finishing treatments.»

The defining characteristic of vegetable tanning, its uniqueness, remains unchanged—and the fatliquoring stage plays an important role in creating it.

«Oil is absorbed differently by the various parts of the hide, and over time everything naturally becomes more uniform. Vegetable tanning is not mathematics: two plus two does not always equal four, because every leather is different and therefore reacts differently to the same process, making it truly unique and impossible to replicate.»