Barncancerfondens Julknapp 2017

VEGETABLE TANNING

The Process

The old expression of "putting something through the mill" originates from the tanning industry
when our predecessors used tanning acids made from oak bark.
We still tan leather like our forefathers did, since this gives the best results.
Producing leather in a way that is safe for the environment is more time consuming than normal tanning.
But what does a slightly longer process matter when the aim is quality?

We produce unique Tärnsjö leather.


STEP
1/10

At Tärnsjö Garveri we use the best raw materials available: Hides from Swedish animals. Thanks to good animal keeping these have less insect damage and enable us to dress the most beautiful leather. The hides are wet-salted and packed on pallets when they arrive from companies specializing in processing raw hides.


STEP
2/10

First, the hides must be stripped. This is done by liming, which is one of the most important processes in leather manufacturing. This stage determines whether the product is to be soft and supple upholstery leather or stiff strap leather. Liming takes two days and is carried out in rotating drums.


STEP
3/10

The limed hide is then taken through the fleshing machine, which removes all traces of fiber. At the same time skilled craftsmen trim the hide from parts of the hide that they can tell won´t qualify for premium leather. They also mark every individual hide with a unique number to make them traceable back to their origin farm. This is to ensure premium quality on our raw material.


STEP
4/10

After the liming the hides are very alkaline. To lower the pH to 8 the hides are treated with a special enzyme, Parkreas, which also dissolves certain albumins and makes the hide pliable. Then the tanning process itself begins and is completed in a few days in our efficient tanning mills.  


The combination of tanning agents has been developed through innumerable experiments by our highly qualified chemists. Each type of leather has its own unique mix.


STEP
5/10

When the tanning process is finished the now wet and heavy hides are first pressed to remove water and flatten the hide. The hide then is shaved down to its desired thickness using another high precision machine.


This is a delicate process of meeting the customer demand. To make sure the hides are shaved to desired thickness the craftsmen continuously do measuring by hand on different places off the hide.


STEP
6/10

Liming and tanning has removed all natural fat from the hide and this has to be replaced. Various methods are used according to the type of leather. Some leathers are treated with fat in a heated fatting mill, while others are aniline dyed and then fatted with water-soluble fats.


STEP
7/10

The leather is now dried in different ways. Some types are dried with hot air, while others are stretched on frames in order to be completely smooth. Upholstery leathers are then processed in a rotating mill by tumbling against each other in order to achieve the desired softness.


STEP
8/10

Experienced sorters examine the leather and trim the hides. This is a delicate process of judging the allover aesthetics of the entire hide in order to place it in different categories of leather and it´s worth. These categories range from 2nd grade, to Prima.


All hides meet the standards of our company to even get this far in the process.


STEP
9/10

The finish of the leather enhances the tolerance and improves the texture. According to customer demand the hides are finished with protective layers and water based colors.


Some hides are also minted at it´s surface if there is a desired aesthetic asked for by the client.


STEP
10/10

The finished leather is measured with an optic measuring devise. The measurement used is Sq.Ft (Ft2). The measuring process is often called the financial heart of the tannery since it determines the amount of leather in each grading that are available for sale. Using various tanning techniques, we create many types of leather differing in thickness, pliability, smoothness and structure.


Our goal is to have an even balance of every grade and type in stock to meet customer demand at any time.