Color is one of those funny things that is extremely difficult to quantify. This is certainly true regarding color of leather furniture. There are loads of variables controlling the color you perceive, from the lighting source to the chemistry construct of the coloring agent (e.g. dye vs. pigment).
Because its so difficult to quantify, most people think in broad terms. Using brown as an example, what version of brown is in your mind's eye? Want to tighten it down further? What does Espresso or Tobacco or simply dark brown mean to you versus the person standing next to you? We all have our own personal version and we're all correct as there is no scientifically established standard, no definitive reference for color definition.
If you are attempting to repair damage on a fine leather sofa, then to conceal the repaired area the color must be exactly matched, else you'll see the difference. The human eye works on detecting contrast. If it's not an exact match, the human eye detects the differential, and draws your brain to its attention. Bingo! You can see the mismatch. Every time you look at the piece, it's what you'll see.
Close enough is not good enough.
Now to dispel a myth. Some color matcher's use a machine (spectrometer). In short, it will get you close, but never exact for a whole host of reasons. Here's the most obvious. The machine is programmed with a specific color chemistry as it's baseline. If the color chemistry you are using isn't the exact color chemistry used to program the device, the machine will interpret incorrectly. If you are painting a wall, you can get away with it, but if your color match requires precision, forget it.
Furthermore, leather furniture often has a mottled coloring technique which presents depth of color as the color variation makes the leather appear more organic. A machine can not read multiple colors simultaneously.
Once again, close enough is not good enough.
Finally there is this intriguing phenomenon known as metamerism. There are multiple versions of this affect, with the most common being the impact of a color your eye records based on the light source. Because perceived color is specific visible light wave-lengths striking your retina, the light source plays a key roll. Incandescent, florescent, halogen, arc vapor, sun all produce differing wave-lenghts. As these wave-lenghts bounce off an object and hit your eye, they influence the color you see. Do a color match under florescent lighting and then view it in sun light and you'll see the difference immediately. For a more complete definition of metamerism check out http://en.wikipedia.org/wiki/Metamerism_(color)
Once again, without the light source being considered, close enough is not good enough.
The professional leather technicians of Advanced Leather Solutions (http://www.advleather.com), color match by eye, in the lighting condition of the leather furniture's location. If that specific light condition can't be recreated, then we opt for sunlight as that provides the broadest spectral reference.
The fail-safe technique we use is very simple. Mix a color that you think you see. Then apply a piece of masking tape to the target leather. With an airbrush or other applicator, color across the leather and over the masking tape. Pull the tape up. If you detect a line, the the color is off and re-mix until you can't detect a line.
That way, you get the color matched perfectly every time.
In our leather technician's training program, it is the subject matter that requires the most time. Coloring matching can be mastered. It takes patience and practice. With experience, a technician gets better and better at it. The most difficult matches involve subtle mottling affects. In this case the technician has to interpret two colors, a base and an overlay print. The interplay of these two colors is what presents as the final color. Our do-it-yourself leather restoration (http://www.DIYLeatherSolutions.com) program success is founded on our technician's creating a custom color mix for a client so the color matches perfectly every time.
We take the guess work out by bringing our experience to the table, because we believe close is not good enough.
As an aside, over a hundred years ago, a painter/scientist named Charles Munsell developed a color quantification system using three variables, hue - value - chroma. His color system comes the closest to a standard and has been used by well-schooled colorists for decades. Check out the Munsell Color Science Labs at the Rochester Institute Of Technology to learn more. - http://mcsl.rit.edu/
Copyright 2009, Kevin Gillan
Showing posts with label leather color. Show all posts
Showing posts with label leather color. Show all posts
Thursday, June 25, 2009
Wednesday, June 24, 2009
Can Leather Colors Rub Off on to Clothing?
One of the most common questions I get asked about a Do It Yourself or professional leather furniture restoration project is: Will the color rub off on my clothes?
It’s a worthy question because there are certain types of coloring agents that will transfer, and others that won’t.
The short answer is that leather dyes transfer, and leather pigments don’t.
Apply a true leather dye (metal complex or aniline dye) to the surface of leather, and dye transfer will occur. The next time someone sits on the leather they’ll be wearing the dye on their clothing.
Whereas apply a pigmented coloring system and there will be no threat of color transfer.
Dyes
The reason is that dyes are free floating, tiny molecules that migrate. They are not made color fast. The dye cannot be “locked” in place if its simply applied to the surface. With a newly tanned hide, the leather can be processed at a tannery such that there is a minimal potential for dye transfer. This is accomplished through heat. The hides are typically dipped into vats of heated dye. The heat sets the dye to the best possible degree. However, take a damp, white cotton cloth and rub it across tannery processed dyed leather and you’ll pull some of the color. In an after market application of dye, you can't stick a leather sofa into a vat of heated dye. So you can't set the dye. The dye will transfer, and quite easily.
One consumer called me in a panic. She purchased Fiebing's leather dye (green) and applied it to her leather sofa. Two weeks later a little girl spilled juice on the sofa. The juice ran off the sofa on to the carpet, carrying the green dye with it. So, not only was the sofa ruined, but so was the carpet.
Pigments
Pigments on the other hand are carried in a specialized chemistry called a “binder” that locks the pigment molecule in place. Most binders are a resin blend of urethanes and acrylics. The combination of pigment and binder is often referred to as a "leather finish." This coloring chemistry renders a topical film on the leather with appropriate adhesion and cohesion properties and when fully cured does not allow color migration or transfer. The key is using a specific type urethane and acrylic chemistry and then getting the blend ratios correct. So if you are going to mix your own coloring system, you should have a solid understanding of chemistry. Use the wrong binders and the color coating will crack and peel.
If a leather technician says he will “re-dye” your leather, he/she probably doesn’t know the difference between a dye and a pigment. If he/she is really using dyes as a coloring agent, then expect the color to rub off. In most cases, the tech is actually using a pigment based coloring system and is referring to it as a dye.
There are two additional Blog entries that offer greater detail explaining the difference between dyes and pigments. They are entitled “Leather Furniture – Dyes or Pigments” and “Leather Color and Attributes.”
Of course you can learn more at our web-site http://www.advleather.com or http://www.DIYLeatherSolutions.com. You can also call our tech line to get more information about Advanced Leather Solutions, or if you simply have a question, we’ll gladly respond. We can be reached during normal business hours in the US at 510-786-6059. For time zone calculations, we’re located in California.
Copyright 2009, Kevin Gillan
It’s a worthy question because there are certain types of coloring agents that will transfer, and others that won’t.
The short answer is that leather dyes transfer, and leather pigments don’t.
Apply a true leather dye (metal complex or aniline dye) to the surface of leather, and dye transfer will occur. The next time someone sits on the leather they’ll be wearing the dye on their clothing.
Whereas apply a pigmented coloring system and there will be no threat of color transfer.
Dyes
The reason is that dyes are free floating, tiny molecules that migrate. They are not made color fast. The dye cannot be “locked” in place if its simply applied to the surface. With a newly tanned hide, the leather can be processed at a tannery such that there is a minimal potential for dye transfer. This is accomplished through heat. The hides are typically dipped into vats of heated dye. The heat sets the dye to the best possible degree. However, take a damp, white cotton cloth and rub it across tannery processed dyed leather and you’ll pull some of the color. In an after market application of dye, you can't stick a leather sofa into a vat of heated dye. So you can't set the dye. The dye will transfer, and quite easily.
One consumer called me in a panic. She purchased Fiebing's leather dye (green) and applied it to her leather sofa. Two weeks later a little girl spilled juice on the sofa. The juice ran off the sofa on to the carpet, carrying the green dye with it. So, not only was the sofa ruined, but so was the carpet.
Pigments
Pigments on the other hand are carried in a specialized chemistry called a “binder” that locks the pigment molecule in place. Most binders are a resin blend of urethanes and acrylics. The combination of pigment and binder is often referred to as a "leather finish." This coloring chemistry renders a topical film on the leather with appropriate adhesion and cohesion properties and when fully cured does not allow color migration or transfer. The key is using a specific type urethane and acrylic chemistry and then getting the blend ratios correct. So if you are going to mix your own coloring system, you should have a solid understanding of chemistry. Use the wrong binders and the color coating will crack and peel.
If a leather technician says he will “re-dye” your leather, he/she probably doesn’t know the difference between a dye and a pigment. If he/she is really using dyes as a coloring agent, then expect the color to rub off. In most cases, the tech is actually using a pigment based coloring system and is referring to it as a dye.
There are two additional Blog entries that offer greater detail explaining the difference between dyes and pigments. They are entitled “Leather Furniture – Dyes or Pigments” and “Leather Color and Attributes.”
Of course you can learn more at our web-site http://www.advleather.com or http://www.DIYLeatherSolutions.com. You can also call our tech line to get more information about Advanced Leather Solutions, or if you simply have a question, we’ll gladly respond. We can be reached during normal business hours in the US at 510-786-6059. For time zone calculations, we’re located in California.
Copyright 2009, Kevin Gillan
Monday, June 1, 2009
A DIYLeatherSolutions client's experience
The following is a direct quote from an e-mail received from a client who recently finished his Do-It-Yourself leather furniture color restoration project.
"I have completed the restoration of my leather couch and love seat. Thank you for providing such a high quality product and excellent costumer service.
Here is my experience briefly recapped:
ALS (Advanced Leather Solutions) did an excellent job of identifying all my material needs and “nailed” the color match for both the base and print colors.
Your DVD and written instructions were comprehensive and nearly all the help I needed to complete the project.
For the two issues that arose that I needed further explanation, Kevin provided a detailed description of what I needed to do and why. He also encouraged me to seek the help of ALS anytime the need arose.
The actual restoration is a job. It is not simple, but is far from complex. I am a very novice do-it-yourselfer, and I was able to complete the project in a reasonable amount of time and with results exceeding my expectations.
As you may recall, most of my issues were cosmetic. The dye in the three year old pieces of furniture failed and they had become aesthetically unappealing. We have a 4 year old boy and a 4 month old baby, so replacing the furniture was not really an option, especially since the leather was in good shape.
The couch looks new (actually the finish is more attractive than the original) and every problem has been resolved (including a few cat scratches).
We are delighted with the results and our decision to take on this project. The high quality products and costumer service you provided are the reason we succeeded. My skills are very modest, but because of what you did for us, the outcome was near perfect.
Thank you for all your help.
Regards,
T. M."
"I have completed the restoration of my leather couch and love seat. Thank you for providing such a high quality product and excellent costumer service.
Here is my experience briefly recapped:
ALS (Advanced Leather Solutions) did an excellent job of identifying all my material needs and “nailed” the color match for both the base and print colors.
Your DVD and written instructions were comprehensive and nearly all the help I needed to complete the project.
For the two issues that arose that I needed further explanation, Kevin provided a detailed description of what I needed to do and why. He also encouraged me to seek the help of ALS anytime the need arose.
The actual restoration is a job. It is not simple, but is far from complex. I am a very novice do-it-yourselfer, and I was able to complete the project in a reasonable amount of time and with results exceeding my expectations.
As you may recall, most of my issues were cosmetic. The dye in the three year old pieces of furniture failed and they had become aesthetically unappealing. We have a 4 year old boy and a 4 month old baby, so replacing the furniture was not really an option, especially since the leather was in good shape.
The couch looks new (actually the finish is more attractive than the original) and every problem has been resolved (including a few cat scratches).
We are delighted with the results and our decision to take on this project. The high quality products and costumer service you provided are the reason we succeeded. My skills are very modest, but because of what you did for us, the outcome was near perfect.
Thank you for all your help.
Regards,
T. M."
To learn how you can have a similar experience with your worn, faded, stained leather furniture, check out this: http://www.DIYLeatherSolutions.com
Thursday, March 19, 2009
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
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
Monday, March 16, 2009
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
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
Subscribe to:
Posts (Atom)