Many of the following statements are controversial and disagree with popular leather care practices.
I've found that some leather care myths are deliberately perpetuated by the industry, especially those on the use of oil based leather conditioners and others are just common errors of judgment. Here is the inside story that the manufacturers of leather care products don't want you to know.
While popularity can sometimes be a reliable barometer, it isn’t always the correct choice for choosing leather care products. Some even make their decision based on new car’s leather fragrance alone. My best advise; research other options and products, test them and then make an objective decision based upon factual information, not hype or brand loyalty.
The most important consideration in leather care is to identify the finish of leather used. Once you’ve correctly identified the leather and / or the applied finish applicable to your vehicle's upholstery, it’s easier to select suitable products / methods (one size fits all is just a vendor's marketing myth)
First you need to identify the material and finishes used; Aniline dyed or Pigmented, Protected or Coated, Alcantara®, Synthetic or Vinyl; BMW and Mercedes Benz use all of these leather finishes for their model range and in some instances a combination. Different types of leather require specific cleaning and care and therefore require a slightly different process. Using an incorrect product could damage the finish; check your 'leather type' before attempting to clean or apply any products to its surface.
Finish leather Cleaning / Care
Unless a Premium Leather option was purchased an 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, then two or three aqueous (water- based) pigmented base coat applications. And then 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 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
Identifying characteristics - this type of surface; it will also have an even shine.
The water-drop absorbency test- water drops will ‘bead’ on the surface
Absorbency rate -Low
(a) Clean - as dirt / grit and subsequent friction cause the finish to wear. Use aqueous (water- based) foam cleaner (Leather Master™ Foam Cleaner) especially on aniline or ventilated seats. Foam encapsulates the dirt so that it can then be wiped away; allow the foam to dwell to ensure the chemicals have time to work. For ingrained soil the best results when cleaning the leather is to use a medium soft bristled brush to agitate the cleaner, this ensures a thorough cleaning
For stubborn dirt use Leather Master™ Strong Cleaner, which can be diluted with distilled water to the required strength; do not apply any liquid cleaning product directly to the surface of finished leather, as it may ‘spot’ clean leaving a faded area? Always apply cleaning products to folded 100% cotton micro fibre towel and then apply using light / medium pressure.
( Hydrated - ( when leather tanner’s talk about conditioning leather they are referring to its moisture content, re-hydration is used to restore or maintain fluid balance (transpiration and evaporation of moisture); not the replenishment or replacement of the fat liquoring, oils and / or waxes.
Water molecules are smaller than the molecules found in polyurethane top coats, so it can permeate the finish in vapour form. This is essential to restore the suppleness and maintain leathers natural flexibility and keeps the leather at its optimum physical performance level, along with softness and strength.
Modern finished leather needs to be kept hydrated with moisture to ensure the leather remains flexible and maintains its soft tactile feel. This is done by regularly wiping the surface with a damp 100% cotton micro fibre towel and by using aqueous (water- based) leather care products. There is no reason to use oil-based leather care products to condition or feed leather hides, check the label if they do then don't use them.
Repetitive heat cycling causes the leather to lose moisture, resulting in the formation of creasing or surface cracks, which may lead to the leather contracting; however the urethane remains stable, which may lead to delamination,
Leather should be hydrated on a regular basis and is somewhat climate dependent. Monthly hydration of leather upholstery in most southern states; Florida, Texas and Arizona, and etc especially during the summer months, would not be out of line
© Protected - is essential as it will protect the surface finish (Leather Master™ - Protection Cream) as a sacrificial layer; this way you are not actually cleaning the Leather's original surface, but cleaning from the surface of the protection. It also makes dirt easier to clean off
Leather Master™ - Protection Cream (a Scotchgard™ type product specifically formulated for lather) the polymers penetrate the surface of finished leather and cross-link to form a durable protective film that is breathable and keeps the leather supple. Being aqueous (water- based) it restores moisture to finished leather and provides a protective sacrificial barrier against all kinds of soiling, water, oil, alcohol-based stains and perspiration marks, so you are cleaning the protective layer
Ultra violet (UV) protection - 303® Aerospace Protectant - is water-based and will provide invaluable protection against photo degradation (fading); especially in a roadster or convertible vehicles. It doesn’t contain silicones, so it won't attract and capture dust. You should apply to a clean surface (it doesn’t contain any cleaning agents)
It will not prevent finished leather hydration (transpiration and evaporation of moisture) as its water-based, although it coats the leather with a micro fine coating; it will not seal it per se.
Note: this product does NOT air dry. Use a second dry cloth to finish the application process. Extra buffing with at dry cloth increases bonding, repellence and durability
(d) Patina(softness) - used to improve and maintain the tactile feel and lustre to ensure the finished leather remains soft and supple; apply Leather Master™ Soft Touch (ex Soft Vital) and allow to dry for approx 20 minutes, finally using a clean dry 100% cotton micro fibre towel buff to a matte sheen. This product is NOT a conditioner per se but is used to restore the softness to hard finished leather; place the car in a sunny location and roll down the windows. Allow the car to sit in the sun for one or two hours to warm the surfaces.
The hides used for automobile upholstery are treated with fat liquor and then sealed at the tannery. The only 'conditioning' required for finished leather upholstery is hydration; oil-based products cannot permeate the finish (urethane pigmentation or covering) that is used in 95% plus of modern automobiles, urethane doesn’t require conditioning or rejuvenation.
Modern automotive leather upholstery use a completely different tanning processes and finishing system, utilizing advanced polymers and chemicals (urethane doesn’t require conditioning or rejuvenation) and as a consequence they do not need to be treated with aftercare products containing oils or proteins. Oils and soft plastics (polymers, acrylics and urethanes) are not compatible; repeated application on to finished leather can cause the break-down of cross-linking and binding agents. Oil accelerates the deterioration of urethane over time. After extended use the condition of the finished leathers pigmentation (colour) will be removed by the oil causing the urethane protection to become delaminated.
Always keep in mind that you’re dealing with the finished coating on the leather and not with the leather hide itself
As the materials used are constantly changing we must maintain our knowledge base and utilize the correct products and application methodologies to keep up with emerging technologies. It is very important to be able to recognise the various finishes and materials used as they all require different methodologies and products for proper care and maintenance
I hope this article has helped you to understand a little more about the special leather finish used for your automobiles upholstery and how to care for it correctly.
Note: Apply all finished leather care products with a 100% cotton micro fibre towel
1. “Reference sources and bibliography used for leather articles” - http://www.autopia.o...tml#post1474865
2. “A Brief History of Leather” - http://www.autopia.o...tml#post1463189
3. “Leather Tanning Process” - http://www.autopia.o...tml#post1455796
4. “Leather Fat Liquoring and Conditioning” - http://www.autopia.o...tml#post1462908
5. “Leather Restoration / Renovation” - http://www.autopia.o...tml#post1479003
6. “Types of Leather Used in Automobiles” - http://www.autopia.o...tml#post1474058
7. “Leather Surface Identification” - http://www.autopia.o...tml#post1451654
8. "Various Leather Surface Conditions and Correction" - http://www.autopia.o...correction.html
9. "Leather care products" - http://www.autopia.o...tml#post1465895
10. "Removing Stains from Leather" - http://www.autopia.o...tml#post1468879
11. “Proper Finished Leather Cleaning and Care” - http://www.autopia.o...aning-care.html
12. "Leather Conditioning" - http://www.autopia.o...tml#post1454835
13. "Using Oil-based Leather Care Products" - http://www.autopia.o...tml#post1450942
14. “Aniline Leather; Cleaning and Care” - http://www.autopia.o...tml#post1455011
15. “Perforated (Nappa) Leather; Cleaning and Care” - http://www.autopia.o...tml#post1455017
[Edit: General up-dates 05.19.12]
Edited by TOGWT, 30 July 2012 - 12:40 AM.