We would like to give you just a brief outline of the history of leather and how it is made.
Leather is the oldest material known to man and has been a natural commodity since ancient times. Its origins go right back to primitive man who hunted wild animals for food and then used the hides and skins left over from the animal carcasses to make tents, clothing and footwear. For example, the use of leather clothing have been found in cave paintings dating back to the Palaeolithic period and bone tools that would have been used to prepare the skins have also been excavated. It is known that as long as 9000 years ago, inhabitants in what is now part of Pakistan made many items of leather, e.g. water skins and bags, harnesses, armour and footwear. The Sumerians around 2500 BC also used leather on chariot wheels. The Egyptians made many everyday articles and military equipment from leather, as seen in wall paintings and artefacts found in their tombs. The ancient Greeks and Romans also used leather extensively and it has remained an important material since then.
The Romans were among those who brought the production of leather to Britain where its manufacture increased steadily. By the Middle Ages, leather was produced for many purposes for clothing, footwear, bags, cases, bottles, saddlery, furniture, binding books and for military uses.
How is Leather Made?
Leather is animal skin or hide that has been preserved and transformed through the process known as tanning. This is carried out in tanneries where they recover the hides and skins that are the discarded by-products of the food industry, thus making good use of what would otherwise be a vast disposal problem with associated health risks. Without getting technical here, the whole process involved in making leather is a complex sequence of chemical reactions and mechanical processes, of which tanning itself is the most important stage that preserves and stabilises the material.
Of course, primitive man used raw, untreated skins and hides and these would naturally quickly decay. Eventually, he found ways to preserve the skins, thus turning them into a crude leather. Early methods included drying the skin, rubbing them with animal fats and other substances, and using the smoke from wood fires. He then discovered that skins could be preserved with an infusion of tannin-containing barks, twigs and other parts of various trees and plants – hence the term ‘tanning’. (Perhaps this came about through the fortuitous observation that skins left on a wet forest floor became ‘tanned’ naturally, which would be because of the release of certain chemicals from the decaying vegetation.)
Originally, oak bark was largely used in tanning. However, it was also later found that earth salts containing alum (potassium aluminimum sulphate) could be used as the tanning agent to produce a soft white leather which could then be dyed with natural plant extracts and was therefore used for clothing and footwear. Leather production gradually became a series of processes that also involved the introduction of other chemicals such as lime and sulphuric acid. Latterly, chrome tanning, with the use of chromium salts, was adopted to produce soft, supple and fine leathers for modern footwear and fashion leather, since the traditional vegetable methods produced leathers that were too hard and thick.
Modern Leather Production with Low Environmental Impact
Some tanneries nowadays are able to produce very fine leathers using natural vegetable-based tannin extracts. As well as being the most eco-friendly type of tanning, using fewer chemicals, it also ensures a lower impact on the environment since the leather produced can be recycled easily at the end of its life and many substances used during the tanning process can be recycled and reused in different ways. For example, hair removed from raw hides is transformed into agricultural fertiliser, sludge from the processing plant can be used to make bricks. However, even when other tanning processes are used, the vast majority of countries with tanning industries have stringent environmental regulations to ensure that the technological advances available now are employed to ensure the safety of workers in the industry and to mitigate any potentially adverse environmental effects.
Steps in the Production of Leather
The principal methods in making leather have not changed that much over the years. However, it is a surprisingly complicated and lengthy process, taking up to several weeks, and carried out by tanners are highly trained in what they do.
The basic steps involved include:
- Curing the hides to stop deterioration, e.g. by salting, chilling, freezing
- Soaking in water for hours or days to clean and replace water lost during the curing process
- Painting, Liming and Fleshing to remove wool from sheepskins, outer skin and hair and fleshy tissues, followed by Deliming to gradually neutralise the pH again
- Pickling in weak acid and salt solutions to optimise tanning
- Tanning to convert the protein of the raw hide or skin to prevent decay and for stability against the effects of acids, alkalis, heat, water and bacteria. Tanning materials include minerals, such as chromium salts, aldehyde and oil and vegetable tannins
- Neutralisation to remove residual chemicals and preparing the leather for further processing
- Splitting or Shaving to the desired thickness
- Dyeing, which can be just on the surface or complete penetration
- Fatliquoring to introduce important oils to lubricate and soften the leather
- Drying to 10-20% water content
- Buffing and Brushing to reduce thickness or produce the desired surface
- Finishing to level the colour, control the gloss and provide protection to resistance water, chemicals and abrasion
After this, the leather will be inspected and graded. The exact specifications and procedures used will vary considerably depending on the type of skin and its intended use.
We hope that this gives you some insight into and some appreciation for all the highly skilled work and time involved in bring you the leather garments you wear as well as any other leather items you possess, whether this be footwear, a bag, suitcase or furniture.