VEGETABLE TANNED LEATHER
Tanning is the process of transforming raw hides to leather. The traditional environment-friendly method which has been practiced for thousands of years to carry out this process is called vegetable tanning. It's called so because natural extracts from trees (tannins) are used in this method. The tannins are the active ingredients responsible for the transformation of the hide into a resistant material.
In Italy, vegetable tanned leather is mainly produced in the Tuscan Leather District particularly in Santa Croce Sull'Arno between Firenze and Pisa across the Arno river.
The Genuine Italian Vegetable Tanned Leather Consortium has 20 artisan tanneries sharing the same standards of production and they all operate in Tuscany region. The Consortium acts as the guarantor of the Tuscan production excellence throughout the world. It created the quality trademark “Pelle Conciata al Vegetale in Toscana” (Tuscan Vegetable-Tanned Leather) which guarantees the quality and origin of the leather and enables the traceability of both the tannery supplying leather and the manufacturer of the finished product.
Map source: vemaps.com
Arno River - Florence
Vegetable tanning is carried out as follows:
1- Preparing (Pre-Tanning)
Curing: Hide is soaked into water and salt to stop decomposition and bacteria growth.
Liming: Hide is then soaked into lime in wooden drums to purify the hide from unwanted elements such as hair, tissue and fat.
2- Vegetable Tanning
This is the process in which hide is immersed into a solution of water and vegetable tannins of different concentrations. Tanning can either be done using:
Tanks: The hides are placed into the tanks filled with the tanning solution. The process is complete in 30 to 60 days.
Drums: Rotating containers filled with the tanning solution in which the raw hides are soaked. The rotation allows for a quicker absorption of the tannins, hence reducing the tanning time from two months to few days.
At this stage, hide has become leather with new physical properties. The leather is allowed to dry for few days.
It's then dyed by artisans, creating flower patterns called " fiore" into the grain during the process. Lastly, the leather is left to dry and then finished with additional colouring, oils, and waxes to enhance durability and colour concentration.
The formulas of selection of tannins and their concentration, dyeing and finishing, to obtain the desired result, are all closely guarded trade secrets that vary from a tannery to another.
Vegetable tanned leather is thus a natural product with superior artisan quality and durability and shall last longer than a lifetime if it's properly cared for. Over time, due to exposure to the world's elements such as air, moisture, heat, light, and body oils, this leather will develop a unique patina, becoming darker and softer and giving an antique effect. It is the mark and manifestation of the natural ageing process of the highest quality leather.
On the other side, there is another method of tanning hides which is chemical tanning. In this method, hide is tanned mainly using chrome. The process takes only one day and produces thinner and softer leather than the leather obtained from vegetable tanning.
Chemical tanned leather is unlikely to have the same longevity of vegetable tanned leather.
This method has a negative impact on the environment since dumping chrome toxify rivers and lands. However, new methods are developed which make use of chemicals that are less harmful to the environment.