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

2 comments:

  1. Hello. I have a black leather purse which is 100% serviceable except the dye has rubbed off. What can i do to restore the color (black) without it rubbing off again? I cannot find another purse like it though i have tried. Please help! Thank you.

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  2. I am so glad I stumbled upon this blog. I was going to dye my leather sofa. It is good quality genuine leather. I want to do it right. Glad I know about pigment vs dying. Thanks.

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