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Today's Leather Manufacture

Much of the leather manufacturing base has moved away from the UK and Europe, predominantly into Asia.The most common raw material used is that of bovine (cowhide). There are typically over 100 steps in making leather and it is a very labour intensive process. Without going too in depth, we'll concentrate on a two key lessons that are extremely relevant to the cleaning and care of your leather.
 
Lesson 1: Fatliquoring
Starting with the wet-end softening process. Known in the industry as fatliquoring, specific oils are added during the tanning or retanning process to make the leather soft, supple and flexible. Years ago, during the old style of processing, the leather was simply 'stuffed' with oils and fats and they were simply left to just sit in the fibre structure. But over time the oils migrated out of the leather, whether through use or heat (such as automotive leathers exposed to the sun which resulted in the fogging haze on the windows). Consequently, these oils needed to be replaced at regular intervals and so the term of 'feeding leather' grew. And rightly so, because back then the leather really did need to be replenished, otherwise it would become hard, shrink and crack. However, leather manufacturing and the development of chemicals used has come a long way!!!! Nowadays, modern fatliquors are technically advanced using high quality, specially processed natural and synthetic oils that meet very high specifications. These are typically fully reacted to the fibre structure, and as a consequence only minimal amounts can migrate out of the leather. Because of this low migration continually adding creams and lotions to replace lost oils is therefore no longer necessary.
 
Lesson 2: Finishing
The finishing process (where a coating is applied to the leather surface for reasons of colour consistency and technical performance) has also changed dramatically. Colour is applied using pigments. Pigments require a binding system to improve flexibility, fastness and adhesion to the leather. In the past this was achieved by using casein and resins, and these products have poorer physical properties like flexibility and colour fastness. Consequently the finish would open up and form small cracks over time. Also products such as nitrocellulose would be used, and their unstable plasticizers would easily migrate in the heat from sun exposure and again create 'fogging' on the internal surfaces of the windows. As a result of this plasticizer migration the use of leather creams, waxes and oils were needed in aftercare products to try and bring the suppleness back into the leather.

However, once again today’s leathers are finished using sophisticated binder systems that incorporate high performance acrylic and polyurethane resins. These modern systems give the leather an enhanced resistance and as a consequence the leather finish should not crack. After two or three base coat applications the clear top coat is applied. The top coat is the final stage of the finishing process, and is designed to make the leather more resistant to wear and tear and improve general properties. Modern top coats are also heavily crosslinked to add even further durability characteristics. The film is of medium hardness allowing the leather extra flexibility and increased physical properties like colour rub fastness, which in turn improves the overall finish. A wide range of additives can also be added to modify the feel and appearance. The light and heat sensitivity is also much improved.
 
As modern leathers use a completely different finishing system consequently they do not need to be treated with aftercare products containing oils. In our opinion the majority of renovation creams marketed today will remain on the leather surface, and simply attract dirt and dust. This feeling is also shared by many of the Technical Directors of the tanneries around the world!!!

The following link allows you to download a brief technical document regarding this subject:

Automotive Interior Leather Document

Also a lot of other detailing product companies state a lot of marketing which is incorrect. The say that most automotive leather is fully breathable. It's not quite strictly true, and infact it has only a small amount of breathability. The following youtube video dispells that common belief:


 
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