Immersion Dyed Aniline Leather

Immersion Dyed Aniline Leather

Research

Correct 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 recommend the same products and techniques be used regardless of the grade or the finish applied or use baffling pseudo scientific techno speak as another marketing ploy; one size fits all is a vendor propagated myth.

All of which makes it difficult to find a definitive, unbiased answer. Using the correct product is important in order to protect your car’s interior. If you keep your cars’ interior clean, you can easily save your car for many years and it can stay in a ‘like-new’ condition, and maintain a better re-sale value. Cleanliness is one of the major things buyers look for when purchasing a vehicle.

Furniture, Motorcycle, Equestrian Automobile leather, are all different types of leather with differing finishes and requires different care. You do need to understand some of the basic chemistry behind the tanning and be able to differentiate between the various finishes applied to automotive leather in able to understand how to renovate, clean or care for them.

There are a few different types of leather and several types of finishes applied to the leather used for vehicles upholstery. There are also a myriad of leather care products available, which need to be used in accordance to the type of and finish used in for your vehicles upholstery.

That is why it is imperative, that if you are concerned about the results you wish to achieve, you must perform a bit of research into finding the products suitable for your requirements.

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.

It had always confounded me that such a simple subject has been made into something so complicated. 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

Materials Technology

Automotive OEM technology is becoming more and more complex requiring educated and skilled technicians to work on them. 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.

Automobile manufacturers have blurred the distinguishing lines on what exactly leather is. Premium leather is the top split of the hide. There are many so-called ‘leathers’ that are actually the bottom split (the fibrous part of the hide) which are covered with a vinyl or urethane coating. Diagnosis is the key, not guess work. Before deciding on what products to use, you need to ascertain the grade of leather and the type of leather finish applied

Be cognizant that the leather and finishes used for automotive upholstery varies from leather industry standard descriptions and although the names are similar the type of leather, pigmentation and finish are often very different. Si it is very important to be able to recognise the various finishes and materials used by OEM’s as they all require different methodologies and products for proper care and maintenance.

Automobile model ranges use different materials for their vehicles interiors; leather upholstery like Aniline Immersion Dyed, Aniline Micro Pigmented, (Urethane) Finished, Artificial leather such as MB-Tex and unfinished materials like Synthetics and Alcantara, and sometimes combinations of products (Alcantara seat inserts on leather seating) as well as various grades of leather hide, full-grain, top-grain and split –grain (which is protected with urethane) all of which require different products and applications methods.

Automobile Interior Environment

The interior environment of an automobile can be extremely demanding on any material used. Temperatures range from hot dry summer days, to freezing nights. Both high and low humidity, even air conditioning that cools, but also dries. Leather's greatest enemies are; sun, heat, body oils, perspiration (that contains urea as well as organic salts and acids) and body heat, which causes acids to become more aggressive and alters the viscosity of oils, allowing them to permeate the leathers finish, and ultra violet radiation, which dries the hide, fades the colour by bleaching, and can cause the leather to fail by drying out the fibres causing the urethane and / or the hide to crack.

Leather Finishes

The leather used for automotive upholstery varies from leather industry standard descriptions and although the names are similar the type of leather, pigmentation and finish are often very different, as is its care. (See the article “Leather Upholstery Type Surface Identification”)

Leather (Fibres) Fibrils

Full-grain leather

Is considered among the best quality leather you can buy. Unlike other types of leather, full-grain leather uses the whole hide rather than layers of the hide. In contrast, top-grain leather, another very desirable product uses the top layers of the animal hide. Using the whole hide makes full-grain leather much thicker, and great for products that require a certain amount of durability.

It can be made from a variety of different animal hides, but most usually is made from cow skin. Leather can undergo complex treatment processes in order to create numerous products. Many of these treatments may result in weaker leather that will not wear as well. This is especially true when the leather is treated with chemicals. Full-grain leather is desirable because of its minimal treatments, breathability and its durability.

With full-grain leather, the hides of the animal used are not treated significantly. Instead they have the hair of the animal removed but they are not sanded. This can result in some minor flaws in the leather, but these are most desired because of their exceptional durability and their actual improvement in look and feel (Patina) the longer they are used

The difference between full and high-grade leather is like the difference between a Bentley and a Dodge. They may look similar on the outside, but you'll soon be able to tell which one cost a lot more to process than the other.

‘Aniline’ leather is very rarely used for automobile upholstery as it is not rigorous enough to stand up to the conditions it would be subjected to. Aniline is an immersion dye method not a leather type per se

Leather Tanning

The first stage is the preparation for tanning. The second stage is the actual tanning and other chemical treatment. The third stage, known as re-tanning, which applies agents and dyes to the material to provide the physical strength and properties desired depending on the end product. The fourth and final stage, known as finishing, is used to apply finishing material to the surface

Proper surface care

Is all about knowing the properties of the surface you want to treat and what product contains the correct formulation of ingredients best suited for that surface. Leather finishes are a very chemically complex material, and if the product is incompatible with it in any way, it can exert a damaging effect: finish peeling, finish cracking, color transfer ("crocking"), yellowing, and general degradation are some of the problems that can be caused by the application of an improperly formulated, incompatible leather treatment product.

Immersion Dyed Leather

Quality manufacturers use only full- grain leathers for this process because they are by far the strongest and most supple part of the hide and, therefore, best suited for upholstery. After the top grain leather has been removed it is bathed in a chemical solution which stabilizes the hide and changes it chemical structure so that it will not deteriorate. The tannery extracts the moisture, oils and natural preservatives and removes the hair; at this stage, it's called ‘Wet Blue’. It is more supple and pliable than vegetable-tanned leather and does not discolor or lose shape as drastically in water as vegetable-tanned. It is also known as wet-blue for its color derived from the chromium. More esoteric colors are possible using chrome tanning.

Then they put the wet blue hides into in large, slowly revolving drums with the new oils and preservatives (Fat Liquoring) Aniline dyes in various colors may be added to the drums at this stage, while the hide is absorbent. They are tumbled and during that process, depending on the thickness of the leather, it can take up to 10 hours for the new life giving liquids to penetrate all the way to the middle of the hide. This is the step in the tanning process that has been so improved in recent years. Finally, the leather is pressed in heated presses, hung up to dry at a certain humidity level, sprayed with finishes and sealers and then pressed again.

The tanning procedures used now are permanent and create a product which will last almost indefinitely. Previous methods employed vegetable derived tanning agents and were not as effective in preserving the leather. If correctly done, aniline dyes are permanent and will not rub off or ‘crock’ after the leather is in use. Immersion dyeing should not be confused with pigmentation i.e., adding color to just the surface of the leather.

If the leather has been vat dyed, the leather will be saturated throughout and a color change is almost impossible. Vat-dyed leather looks better much longer since the color shows well after cracks form and wear patterns emerge

Immersion dyed top-grain leather  is used in prestige European automobiles -  Aston Martin, Audi, Bentley, Ferrari, Jaguar, Lotus, Lexus,, Range Rover and Rolls Royce, US - Cadillac and high-end German automobiles such as Audi, BMW, Daimler AG, Mercedes-Benz and Porsche . Some super expensive exotics and luxury vehicles still use this type of leather. But due to its hard to care for nature some vehicle manufacturers are slowly phasing it out in favour of Micro Pigment finished leather

Identifying characteristics – due to the dye process the colour permeates the leather and the dyes are permanent and will not rub off or ‘crock’. The leather is absorbent and has a random shade colours and grain pattern, lightly scratch the surface to see if it reveals a lighter colour.

The water-drop absorbency test- water drops will permeate the surface and darken its colour (temporarily)

Absorbency rate – Medium High

Micro Pigment Finished Leather

Semi-Aniline finished leather is a alternative finishes for aniline leather; using top-grain leather that is immersion dyed and then a micro thin transparent polyurethane covering is added, which may contain pigmentation (colour) and an abrasion resistant additive. This type of finish is sometimes called semi-aniline and is may be offered as Milano, Silk Nappa, Valcona (Audi) Boston, Baseball, Dakota, Montana, (BMW) Chaparral leather and Porsche  interiors.

The water-drop absorbency test- water drops will bead

Absorbency rate – Medium

Semi-Aniline finished leather is somewhat absorbent, which means that any spills, body oils etc will eventually soak into the leather hide. It should be routinely cleaned to remove light dirt and dust by using specific aniline leather cleaner that that will clean the surface of the leather, without being absorbed, or force the soil into the leather.

This type of finish is porous (to moisture and oils) but in these cases we would be trying to prevent the absorption of oils into the leather as they can cause an imbalance which would then have to be rectified. Body oils can also cause many problems with leather of this type, as they are acidic, leaving unsightly patches which are expensive to fix.

In addition to regular cleaning to remove abrasive debris and oils, leather requires regular replacement of its moisture (re-hydration) by regular use of a damp 100% cotton micro fibre towel.

Semi-Aniline finished leather is moisture sensitive, so avoid the use of oil or wax-based products as they may negatively affect the evaporation and hydration moisture balance. Aqueous (water- based) products will help to hydrate the leather and maintain necessary moisture

The oils secreted from your skin are slightly acidic and may cause the leathers pigmentation to lose its colour prematurely, taking away the effect of a premium leather interior. Removing these oils is paramount to leather care, but limiting the amount of bare skin you expose to your seats and interior is a great way to prevent discoloration. This type of leather can be renovated with a pigmentation coating 

Removing Stains

•          Surface dirt and dust – use a soft brush, vacuum and then use a clean, damp cloth

•          Spills – use a dry 100% cotton micro fibre towel to absorb liquids, and then wipe clean with a damp 100% cotton micro fibre towel.

•          Stains – use a mild leather cleaner (test on an inconspicuous place before use) using very little pressure and do not ‘scrub’ to remove

•          Water marks - wet the whole panel while the area is still damp and this should then dry evenly. However if the water has dried and permeated the leather leaving a hard edge no amount of cleaning will resolve this.

•          Oil stains – should be removed immediately, if allowed to permeate it will stain. Leather Master Leather Degreaser is applied through a spray. It dissolves the oils and transforms them into a powder that is more absorbent than the leather. This powder is what is wiped off, cleaning and degreasing the leather. Allow the white powder to dry fully. If the powder is drying to a yellow colour, it means that there are still a lot of oils in the leather.

·         For resistant strains specific cleaning product are available, but be aware that certain stains may not be removable, i.e. dye transfer from leather belts and jeans, coffee, penetrated sun tan oil, food sauces, citrus fruit drinks, etc are especially difficult to remove. On this type of leather anything that is allowed to permeate the leather may stain it permanently as it is not possible to clean out of leather.

·         Clean accidental spills right away, do not allow liquid to soak or ‘heat set’ into the leather. It is very important with this type of leather to use a protective aqueous (water- based) type protection product, which will inhibit dirt and body oils etc from being absorbed into the leather in the first place; these can then be cleaned from the surface easily. Micro pigmented leather fades at a faster rate than protected leather, so ultra violet (UV) protection is of paramount importance.

Aniline Leather Care

Simple cleaning, hydration and protection are the three steps that will prolong the life of Micro pigment finished leather. Always pre-test the product on a hidden area. Shake the foam container thoroughly. Spray the product at a distance of 12 inches from the leather to one section at a time, and allow product to remain in place for approximately 15 to 30 seconds.  

Aniline finished leather doesn’t require conditioning or rejuvenation; just keep the surface clean and hydrated.  

1. Cleaning - there are two cleaning-related factors that can cause your leather to wear prematurely.  The first is dirt, and the second is oil, combined they become very abrasive, as dirt / grit and subsequent friction cause the finish to wear

Remove surface dirt and dust, cleaning the seams periodically is important as dirt / grit will abrade the stitching causing them to fail, prise them apart, then use a soft brush, vacuum and then use a foam cleaner, one section at a time, and then finally wipe off with a clean, damp 100% cotton micro fibre towel

The advantage of foam over liquid is the minimum amount of moisture, very important for cleaning absorbent and moisture sensitive leathers.

 Use foam cleaner, which should be given dwell time and then gentle agitation with a medium stiff bristled brush to get the product into the materials surface, the low moisture content of foam can then be easily rinsed and the surface dried. Remove excess product and debris with a clean, damp 100% cotton micro fibre towel. If the foam is allowed to dry the soil will be re-deposited to the surface. Check the results and repeat process as necessary

For heavily soiled areas use a foam cleaner (Leather Master™ Foam Cleaner) that contains a surfactant that will lift dirt and soil, allow react time to do its work and then use a soft brush to agitate and loosen the dirt (Swissvax Leather Brush) especially on light coloured leathers; this enables the cleaning of the micro pores and creases and lifts the dirt out and reveal any further work that needs doing (dye transfer, stains, etc)

2. Hydration – 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.

Moisture balance is a sine qua non (an indispensable and essential action) in leather care.  Leather naturally absorbs and retains moisture vapour, meaning it’s also susceptible to losing the moisture necessary to keep it pliant and soft. One of major attribute is its ability for transpiration (allowing the movement of moisture back and forth (evaporation and hydration), which it does even better than wool.

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 it delaminating.

A regular wipe down with a damp towel on a regular basis is all you need to condition and / or hydrate finished leather, and  by using aqueous (water- based) products that do not contain oils and/or waxes, check the label if they do then don't use them. Leather should be hydrated on a regular basis and is somewhat climate dependent.

Patina - Leather Master™ Soft Touch - is not a conditioner per se but a water-based product used for revitalizing and restoring the tactile feel of older leathers and also to improve the feel of stiff leathers

3. Protection - is essential as it will protect the surface finish, without hindering transpiration, while acting 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, allowing transpiration 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

Swisswax Leather Glaze -drastically reduces signs of wear and ensures that new leather remains new and in mint factory condition. A colorless protective layer, which drastically reduces any signs of wear on the driver’s seats, side bolsters, steering wheels and shift knobs are places where the leather undergoes the most noticeable wear - even on new cars. It noticeably reduces surface friction and gives added protection from jeans discolorations

3a. Ultra violet (UV) protection - 303® Aerospace Protectant will provide invaluable ultra violet (UV) protection  against photo degradation (fading); especially in a roadster or convertible vehicle, steering wheel and dashboards

Is water-based and will provide invaluable ultra violet (UV) radiation protection against photo degradation  (fading) protection; 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 it’s 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

Maintenance:

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

Leather Master™ Soft Touch - apply and allow to dry for approx 20 minutes, finally using a clean dry 100% cotton micro fibre towel buff to a matte sheen.

I hope this article has helped you to understand that little bit more about the leather finish in your vehicles upholstery and how to care for it correctly

Associated Articles

1.        “Reference sources and bibliography used for leather articles” - http://www.autopia.org/forum/autopia-detailing-wiki/138755-reference-sources-bibliography-used-leather-articles.html#post1474865

2.        “Leather Articles Hyperlinks” http://www.autopia.org/forum/autopia-detailing-wiki/141973-leather-articles-hyperlinks.html

3.        “Aniline Leather (Micro pigment) Cleaning and Care” http://www.autopia.org/forum/autopia-detailing-wiki/137167-aniline-leather%3B-cleaning-care.html#post1455011

I would like to think that these articles become an asset to anyone who is new to detailing and to professionals alike, as well as industry experts who seek to advance their knowledge.

I hope the above article was informative. By having some understanding of the ‘What’ and ‘Why’ as well as the ‘How’ along with a little science to help you understand how the chemicals we use react, you can achieve the results you desire.

I would appreciate it if you would share this article as it helps other detailers further their knowledge.

Questions and/ or constructive comments are always appreciated.

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