Leather Furniture - Dyes or Pigments?

I am often asked to explain the difference between aniline dyed leather (unfinished) and protected or pigmented leather (finished) furniture. This post gives you the straight scoop between dyes and pigments as relates to leather furniture.


First, let’s cover some base-line information about leather to help you better understand its properties. Leather is a natural product. It comes from animal skins which have been chemically processed (tanned) to preserve them. A properly tanned hide (or skin) creates strong, flexible leather, resistant to decay.


Most leather upholstery found on furniture and in automobiles is tanned cow hide. Cow hides are about 1/4 to 3/8 inches thick, which is too heavy for general upholstery application. Therefore, hides are split laterally, rendering an upper and lower cut.


The upper portion is the top-grain, or full-grain. The lower portion is the split. This cutting process creates different “faces” to the leather. The outside face of the top- or full-grain shows the natural grain characteristics, but is otherwise smooth, whereas, the underside appears as suede.


There are two basic categories: Finished or Unfinished. Briefly, finished leather is first dyed via immersion in an aniline dye solution, and then the outside face of the hide is coated with a pigmented resin, and then a subsequent clear-coating. Unfinished leather processing stops at the first dyeing process, without any resin coating. Finished leather is protected by the color-coating and clear-coating, and unfinished is unprotected, not having either of these subsequent coatings applied.


The key point is the color you see on a finished leather is from a pigment coating on the leather, whereas unfinished leather color is a dye in the leather. Finished leather is stain and fade resistant but lacks deep richness in color, and tends to be stiffer. Unfinished leather is soft and natural-looking but fades and stains readily. Unfinished leather tends to be more expensive as only the finest, cleanest (fewer unsightly characteristics such as hide scars, branding marks, etc.) hides can qualify as unfinished.


This graphic depicts the difference between finished and unfinished.



Note that all cases (finished and unfinished) the leather is aniline dyed.

You can see that the topical coating can range from thin to thick. If there is a very light color or clear coat on top of aniline-dyed leather, it is often referred to as “semi-aniline.” Semi-aniline leather offers modest protection while retaining much of the aesthetic beauty of unfinished aniline-dyed leather. These are the arrtibutes of finished and unfinished leather furniture.

Finished: The leather has a topical pigment coat applied. One of the most common coatings consists of a soft acrylic color coating under a urethane clear coating (for durability). These resins create a film that bonds to the surface of the leather. Its primary goal is to protect the leather, providing wear, stain, and fade resistance.


Finished leather will resist staining by water- or oil-based agents (if a drop of water is put directly on the leather surface, the water bead remains on the surface, and does not soak in and darken the material). The clear coating determines the final reflective value of the leather surface (ranging from high gloss, to matte). Generally, finished leathers do not have that "buttery soft" leather feel (or hand) associated with raw leather. Also note, finished leathers can be described as aniline-dyed, and still have a topical pigment applied. Finished leathers are much less susceptible to fading


Unfinished: The leather does not have a topical pigment applied, or has a minimal resin coating to retain the hand of raw leather. The color is achieved by immersing hides in aniline dyes that are absorbed into the leather, accentuating the natural beauty of the hide. Because leather's absorption characteristics are not uniform, variations in color are common. The water drop test will result in the drop transferring into the leather, darkening or staining the area. Unfinished leathers are colored using organic aniline dyes which are highly susceptible to fading (caused by UV exposure).


For more detailed information visit http://www.advleather.com/.


Copyright 2009 Kevin Gillan

Leather Colors and Attributes

The phone rings and answered: “Advanced Leather Solutions, how can I help you?”

A common opening response is: “I have a problem. It seems the color of my leather sofa is disappearing. What’s going on and can it be corrected?”

After a few qualifying questions, a conclusion is reached. The leather is suffering from print coat failure.

To understand what that means requires some background knowledge. Most upholstery leather is vat dyed (aniline) and then a pigmented coating is applied to the surface (more on the difference between dyes and pigments in another post). The topical color presented comes from a cocktail of pigment molecules mixed to create a specific rendering (i.e. brown). The pigments are blended in a resin-based chemistry called a “binder.” The result is referred to as the colored “finish.” All of this is then sealed with a clear coat which is the primary protection.

Now, here’s the meat of the matter. The binder and clear coat are chemically engineered with several important attributes:
1. Elasticity -- they have to flex and move as the leather flexes and stretches when sat upon else they will crack.
2. Cohesion – they have to establish a durable, wear-resistant film where each molecule links or “sticks” to its adjacent molecule else the will wear quickly away.
3. Adhesion – they have to adhere permanently to the surface else they will peel up.
4. Chemical Resistance – they should withstand the rigors of an active household else will wash away, sometimes simply with water.
5. Low Profile – they should follow the topographic contour of the leather flowing down the side, across the valley floor and up the other side of the grain pattern on the hide else they will bridge over the grain pattern, obliterating it.

Without these attributes the finish will come off, peel up, crack, appear like plastic (vinyl), etc.

Base and Print

To address the issue above, there is one other variable to consider. To present a color that looks natural a layered coloring technique is used. This is called a “base and print.” The base coat (lighter color) uniformly covers all leather surfaces. The print coat (darker color) is then erratically applied without complete coverage creating a mottled coloring affect. The technique gives the illusion of color depth, or a more natural look, resembling how a dye would render in leather.

It the case of the common question mentioned above, the tannery failed with at least two attributes: 1. Adhesion, 2. Chemical Resistance. The clear coat has eroded away and the print coat has been either worn or chemically removed (sometimes with simply water), exposing the base coat. Thus print coat failure ensues exhibiting as lighter color (the base coat) in the problem area. Often the problem is described as fading.

This is a correctable condition. It requires application of the missing print coat and then top-coating with a more durable chemistry so as to avoid the same problem from reoccurring.

As professional leather restoration and repair technicians, we see common threads of weakness in leather furniture. Typically there is a failure at some level in the basic chemical composition of the finish applied at the tannery. With an understanding of the fundamentals, we can generally develop a fix that solves the problem. However, it’s important that the “fix” itself not be problematic.

Here’s the rub. There are people representing themselves as leather repair technicians who have no clue about the fundamentals and cannot distinguish the difference between quality finishes and terrible finishes.

For example, many technicians will use colored finishes that have been engineered for vinyl or plastic. Leather is a very different material as it’s organic, not synthetic. This differential is important. Vinyl colors when applied to leather often crack and peel over time. So, it’s vital to determine if the color chemistry the technician is using is specific to leather. If the technician represents that he/she uses the same color chemistry for both vinyl and leather, then that is a prescription for failure.

To learn more about leather finishes, go to http://www.advleather.com/. Click on the leather care button. There you’ll find a description of the various types of leather and their finishes. You can also call our technical staff at 510-786-6059.

Copyright 2009 Kevin Gillan

How to tell if leather is quality or junk.

As a professional leather technician, this is a frequently asked question: “How can I tell that the leather furniture I am buying is made with quality leather?”

It’s not always easy. The leather may look and feel comfortable in the showroom, but how will it hold up in your home?

The sales-person may tell you that it’s a grade “A” leather or a grade “2000” leather. Or some other nomenclature that sounds impressive. What does it really mean?

In a word -- nothing.

The grading system used by each leather furniture manufacturer to classify the upholstery leather installed on their furniture is not based on any industry-established standard. It’s typically marketing hype. One manufacturer’s “B” grade, is another’s “100” grade, or “1000”, and so on.

Don’t be swayed by some official-sounding label applied to leather upholstery by the furniture sales-person, or the marketing material produced by the manufacturer. Instead, ask the following questions:

1. Is the upholstery leather un-corrected top-grain? - This is leather with the greatest durability. Read the literature offered by the manufacturer. Even then, be wary. Recently a client brought a cushion into our shop from a “hide-a-bed” sofa that the manufacturer’s documentation claimed to be top-grain leather. This manufacturer, who shall remain nameless (but whose initials are JC where the J is consistent with the actress whose last name is Aniston), is misleading consumers in its printed materials. In this client’s case, the leather was a low quality split-hide, which is clearly inferior leather, and clearly not top-grain. To read more about top-grain leather go to http://www.advleather.com/ and click on the Leather Care button.

2. Is the furniture fully upholstered with leather? - Ask if any of the upholstered sections on the piece you are considering have been upholstered in vinyl. There are issues to be considered with leather upholstery when it is mated with a synthetic material like vinyl. The seam line where the leather and vinyl meet is a potential source of problems. The vinyl often fails along that seam line and there is nothing that can be done to correct the problem except re-upholstery. And, that’s an expensive option.

3. Is the upholstery leather protected or unprotected? - Protected leather implies that the leather has a topical, pigmented coating on the surface. This upholstery leather is excellent for high-use environments, such as an active household with children, pets, and so on, where the leather may be exposed to spills, and other household hazards. Unprotected leather implies upholstery leather that is unfinished. That is to say, it has no topical, pigmented coating. This is often called pure aniline-dyed leather. The color presented comes from the dye in the leather. Because there is no protection on the leather’s surface, it is aesthetically vulnerable. It will stain and fade. So, this type of upholstery leather looks gorgeous and feels wonderful, but will not hold up well to the rigors of an active family room, with kids, dogs, etc. The sales-person may make the claim that their unfinished, aniline-dyed leather has been “treated” to resist staining. This may be true, however, the treatment is never permanent or fully effective (anyone familiar with the temporary nature of a “scotch-guard” type treatment will have a good idea what this means). Client after client has complained to me that their “treated” unfinished leather suffered staining within a month or two, or sooner.

4. Is this material bi-cast? – If the answer is yes, prepare yourself for a short life expectancy. Bi-cast, sometimes referred to as PU Leather, is a composite material much like fiberboard or pressed wood isn’t really wood, but rather made from wood fibers. Like fiberboard, it lacks the tensile strength required for regular use. Furthermore, it delaminates (peels), and tears fairly easily. To read more about bi-cast, read the article under the consumer tips section of http://www.advleather.com/.

In the end, as a consumer, you are on your own. Your best option is to arm yourself with as much information as you can before you buy. Then ask the key questions, and be wary of the sales-person who is evasive in his or her answers.

As a further resource, email kevin@advleather.com, or call Advanced Leather Solutions @ 510.786.6059 (USA) to answer questions. You’ll get straight-forward, no nonsense answers.

Copyright 2009 Kevin Gillan

How to clean leather furniture

“How should I clean my leather furniture?” It’s a common question from our clients.

Often, we hear that they have been using saddle soap. After all, it seems like the right thing to use, as certainly saddles are made from leather.

Despite what it seems like, it’s a mistake! You see, leather intended for saddles and leather intended for furniture are processed very differently.

Saddles are made from heavy-duty belt leather which is vegetable tanned to withstand the harsh environment of the out doors. It’s tough, highly durable leather and can stand up to the use of chemically harsh leather cleaners, like saddle soap.

Upholstery leather is processed differently. Using chromium tanning chemistry, the end result is soft, supple leather that is much more sensitive to harsh cleaners like saddle soap.
Think about your own skin. Would you wash your face with a strong household cleaner like 409? Certainly it would clean your face, however the drying and chaffing effect it would have on your skin is not desirable, particularly with repeated use. The same is true for upholstery leather.

The fact is that upholstery leather is acidic. It has a pH of 4.5 – 5. Harsh cleaners are highly alkaline. Consequently a chemical reaction occurs in the leather that breaks down its fibrous structure and stiffens the leather. Therefore it’s important to use leather cleaners that are chemically engineered (pH balanced) specifically for upholstery leather. If you would like more information about appropriate upholstery leather cleaners and conditioners, visit our http://www.advleather.com/ under our consumer products button. Watch this video to see how a quality leather cleaner that is pH balanced to leather works: http://picasaweb.google.com/kpgillan/SG5Demonstration#5050767770458259346

Copyright 2009 Kevin Gillan

The Real Facts about DIY Leather and Vinyl Repair

You’ve seen it on TV - the magical do-it-yourself leather repair kit that eliminates a major tear in any leather surface “in just minutes!” The color is always perfect, and so is the grain-pattern. It’s simply amazing. How can this be? Leather repair and restoration specialists, with many years experience of constant, day-to-day practice may take hours to achieve similar results. But on TV, it happens “in just minutes!”

Now for the reality check. Small problems have turned into big problems --- big problems have turned into utter devastation “in just minutes!” AS professionals see this happen regularly even with customers that are technically astute. Many of them are people who remodel their own homes, restore their own cars, etc. They’re experienced at Do-It-Yourself (DIY) projects and aren’t afraid to tackle a new one. So, the question is: Are the companies selling these Do-It-Yourself leather repair kits on TV misrepresenting the process?

This picture is a case in point. The customer had cat scratch damage on several areas. The customer purchased a repair kit that included several colors and a mixing chart. What you see the customer’s attempt at color matching. Not only is the hue very wrong, but it’s also flat and muddy compared to the rich, bright brown of the original.

The lesson learned here is that despite what TV and website advertisers claim, successful leather repair requires time, attention to detail, and a willingness to forego instant gratification.

The formula or product that will give good, long-lasting results with little or no effort is an illusion. However, that doesn’t mean that do-it-yourself leather repair is impossible. It simply means that the project be approached with realistic expectations and a willingness to follow the appropriate procedures with the right materials and help from experienced technicians.

Repair Process Overview

There are many types of leather. For simplicity sake, our focus here is the most common leather found on furniture and automobiles. Its call finished leather.

There are two types of typical damage to upholstery grade finished leather:
1. Damage that affects the topical color only.
2. Damage that affects the color and the underlying leather fibers.

To address each condition, there are two primary components of a leather repair kit. The first is fill material (also referred to as fill or repair compound), which is used to fill any void in the leather created by the damage (cut, burn, gouge, etc.). The second is the surface colored finish. Some sold on TV kits mix the color directly with the fill compound. In the interest of not boring you beyond all reason, let me just say that this is a bad idea on many levels. If you’re the type that absolutely must know then email me (Kevin@ADVLeather.com) and I’ll support my point with specific facts.

Repair Compounds

An internet search under “leather repair kits” will yield site after site that offers do-it-yourself leather repair kits. Usually, it’s something called Leather-“blah”, where “blah” is any descriptive term that implies “As if it never happened – in just minutes!”.

Here’s the rub. Many of these kits are based on chemistries intended for vinyl repair. These sites suggest that their kits are suitable for leather, or vinyl. Let’s look at the facts about what you are buying.

The fill compounds used for vinyl repair are oil-based. Oil impregnation is an underlying chemical basis for vinyl as an upholstery material. The active ingredient that offers wear resistance is a solid (PVC), which is (as you know if you’ve ever held a piece of PVC pipe in your hands) a stiff, hard plastic. This plastic is heated and mixed with oils, which give flexibility to the finished product. This is all fine, if you’re using oil-based fillers on vinyl, where the damaged area of material is chemically similar.

The fact is leather is quite different. It is an organic material and absorbent by nature (imagine a leather chamois that you’d use to dry your car). When you apply oil-based filler to leather, over time the oils migrate into the surrounding leather fibers leaving the PVC solids behind. The fill compound then reverts to its natural state (stiff PVC plastic). Because the oils are no longer present to soften the fill material it stiffens and subsequently cracks when required to flex (i.e. the seating area of a sofa). So, lesson one is to use fill material that has been chemically engineered for leather.

Color Chemistry

Now we come to the color application. This is the part of the repair process where you apply color to conceal the damage including the fill compound, if it were necessary.

There are two components that make up leather or vinyl colored finishes, binder and pigment. The binder is basically a clear film or resin which encapsulates or binds (hence the name) the individual pigment molecules in place. The pigment presents the actual color. In combination, the binder chemistry holds the pigment molecule in place, each over-lapping its neighbor, so that a field of over-lapping pigment molecules is seen as an uninterrupted field of color. This is the same principle represented in any paint medium, from house paint, to car paint, to canvas acrylics, etc.

The chemical engineering behind the binder determines the characteristics of the colored finish. If it is a stiff resin, it will not have good flex properties. If it is a soft, pliable resin, then it will have good flex properties. Since leather is required to flex, then soft resins are key. However, many flexible resins don’t have good chemical or wear-resistance. So it’s a blend of resins each imparting its own physical characteristics for good wear resistance in combination with high flex characteristics. There is a lot more to the story that goes beyond the scope of this article however, the following lists the attributes of good materials used for leather repair and coloring.

1. They should pass the test of time and repeatedly flex over the life of the leather.
2. They should have good chemical resistance (from water, to caustic cleaners, to solvents).
3. They should have a low profile, so the color film follows the fine grain pattern of the leather and not bridge over the valley of the grain.
4. They should have an inviting tactile quality, and not resemble a piece of plastic.
5. The colors should have excellent covering power yet present bright, clear hues.


The Color Match

Now add the art of color matching and you have the ingredients for a repair that is essentially invisible and will last the life of the leather. Color matching is an acquired skill. If you’re off even by a little bit, you can see that the leather has been repaired. For best results, access to color matching professionals would make the DIY repair task so much easier and dramatically improving the probability of an invisible repair.

Let’s take another look at that disaster cat damaged sofa with the terrible color match and what it looks like when repaired and color matched correctly.


So, let’s review. For best performance the colors and fill material are chemically engineered uniquely for leather, not vinyl. And the color is matched correctly.

As leather technicians, our goal is to provide a permanent solution. We need quality materials to do our job. After years of continual improvement and testing in the real world of professional repair and restoration we have created state-of-the-art fillers and colors for our own professional use. We now make them available to you. The components of a DIY ADVLeather.com repair kit are the same fill compounds and colors that we use professionally.

We also offer professional color matching services, placing the burden of getting the color right in the hands of experienced pros.

If you’re willing to invest the time and effort necessary, then the repair you want can be accomplished using the same materials and techniques we’ve used for years and with our help color matching.

To help guide you we include detailed instructions, often via DVD video. And, we’re here if you need technical support. We want the result of do-it-yourself leather repair to be what it looks like on TV, but with a dose of reality. Our goal is to empower consumers with quality materials and techniques, offering the option of resolving leather furniture problems through quality and effective DIY Leather solutions.

Copyright 2009 Kevin Gillan