Leather used for Automobile Upholstery

[togwt]

Information regarding the care of leather is scarce, often contradictory, misleading, or simply wrong. Misinformation can lead to inadvertent damage to your vehicles leather upholstery; my goal is to present clear, concise, accurate information.



There is a great deal of conflicting information on leather care being put out by leather experts themselves who use baffling pseudo scientific techno speak as another marketing ploy, which makes it difficult to find a definitive, unbiased answer. It had always confounded me that such a simple subject has been made into something so complicated.



After various meetings and discussions with leather tanners, their research and development teams, chemists and fat liquoring formulators and many leather care product manufacturers I’ve gained an understanding of this versatile material on both a practical and scientific level.



I have always thought that the more facts and information you have at hand the easier it is to judge what information you are being given. After all, how can you fully understand and properly use any product unless you have all the facts? In the final analysis; it’s your vehicle, your hard earned money and your choice



Leather Hides



Leather is the fibrous corium or structural part of animal skins as shown above in microscopic cross-section. For a material that is so versatile, stylish and practical you could be fooled into thinking it is an extremely complicated material...far from it.



There are basically just three main materials from which hides and skins are made: water 60-65%, protein 25-30% oil and fats 5-10%. The protein is mainly collagen (found in many cosmetics) and it is this collagen that is transformed into leather by the tanning process.



Raw leather hides have four main parts - an epidermis, grain, corium and flesh



Two of these layers, the epidermis (which is a thin protective layer of cells during the life of an animal) and the flesh are removed during tanning by a process called liming.



This leaves just the grain and the corium, the parts that are used for automotive leather upholstery .The grain layer is made of elastin protein fibres. The grain carries many distinctive marks such as insect bites, growth marks and wound scars giving the leather a unique appearance.



The corium is packed with collagen protein of the most abundant proteins in tissues such as skin, bone, ligament and tendon where it occurs predominantly in the form of large elongated fibres called fibrils that are arranged in larger bundles and interwoven to give the structure great strength, and its structure varies quite a bit depending on the age, breed and lifestyle of the animal. It also provides excellent elasticity and durability.



In the tanning process these fibres and impregnated with collagens and polymers that are designed to hold them together and keep them supple. Much of the suppleness of leather comes from its moisture content. After tanning the skin is protected with a thin pigmented (colour) urethane and then a clear abrasion resistant topcoat.



The thickness of the corium increases with age which is why calfskins are thinner, smoother and softer than the hides of mature animals. Hides from cows are smoother, thinner and softer than the hides of mature male bull hides which are thick, tough, course grained and very strong.



When corium fibrils lose moisture they shrink, when they are hydrated with water moisture they swell. The best way to care for finished leather and to keep wrinkles to a minimum is to keep the leather properly hydrated and avoid, as much as possible, these shrinking and swelling cycles. Keeping leather hydrated only requires a regular wipe down with a damp cotton towel



Finished Leather



It is somewhat of a pity any finish at all has to be put on leather as in its fully tanned but unfinished state it feels and looks superb. Unfortunately though in that condition it is absorbent, can be affected by strong light and is prone to attracting soil and becomes very dirty



Unless a Premium Leather option was purchased Isocyanate based ethyl carbamate (urethane) finished leather upholstery is used by 95% as OEM in modern automobiles. It comprises a multi stratum acrylic and polyurethane resin binder system covering over the leather hide; the top strata are the surface pigmentation (colour) and an abrasion resistant urethane is used to improve flexibility, fastness and adhesion to the leather. It absorbs water vapour but it doesn`t readily absorb liquid, so rain will not harm it and a damp cloth can be used to keep it clean.



Two or three aqueous (water- based) pigmented base coat are applied and then finally a clear aqueous (water- based) top coat is applied as the final stage of the finishing process, which usually includes additives to give it a soft feel (patina) and abrasion resistance, as well as a limited amount of ‘slide’ to assist in entering and exiting the vehicle



It also has micro-pores that allow transpiration (evaporation and hydration; the passage of water vapour through a membrane or pore) they are not sealed per se. Oils are not compatible with water-based pigmented urethane coatings and their molecules are too large to permeate, so they remain on the surface to be removed by clothing



Real leather has a recognizable fragrance that is missing from polyurethane and plastic. Simple cleaning and protection steps that will prolong the life of finished leather;urethane doesn’t require conditioning or rejuvenation



Modern tanning and coating processes leave leather dynamic and self-regulating with regard to the moisture content therein. Repetitive heat cycling causes the leather to lose moisture, resulting in the formation of creasing or surface cracks, which further leads to the leather shrinking; however the urethane remains stable, which may lead to delamination.



Associated Articles



1. “Reference sources and bibliography used for leather articles� – http://www.autopia.org/forum/autopia...ml#post1474865



2. “Leather Articles Hyperlinks� http://www.autopia.org/forum/autopia...yperlinks.html

[stanleyg]

Thanks for the information.It is imperative that we have a complete information for the leather being used for automobile upholstery. In this piece of information, you have presented a clear picture of how to take care of the leather for the automobile upholstery and how to maintain it so that it lasts for the upcoming years.

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car upholstery

[togwt]

I appreciate your thoughts and the rare ‘thank you’ for the information provided.

It’s a shame that it comes disguised as SPAM