Ask the Expert Question-and-Answer Archive

by Ron Joseph

August, 2002

Color Matching of Paints, Inks and Dyes - Metamerism

Q. A dye is selected for a paint. the dye, dissolved in toluene, is matched to the paint chip. However, the results do not match the painted sample(same solvent, toluene). What are the possible causes? Is it the reason UV degraded the pigment and film? If this is so, how can I add UV resistance to the paint?

A. If you want to match a paint, you need to start with a color standard that is made of paint pigments ... in fact the same pigments that you intend to use in the new paint.

If you use a dye or a color chip that is made of anything other than the pigments that you intend to use in your new paint, you might run into the potential problem known as "metamerism."

Although the standard color might match the new color when viewed under one light source, it might not match in any other light source.

For instance, if you go to a boutique and find a dress, shoes, and other garments that match while you are in the boutique you might find that as soon as you come home and view the same items in sunlight, incandescent or fluorescent light, they no longer match. But as soon as you go back to the boutique and compare them in the boutique lighting, they do match.

Unfortunately, there is nothing that you can do about this. It is a property of colors. Even if you have the SAME paint and apply one sample to one type of substrate and another sample to another type of substrate, you can still experience metamerism, but probably not as dramatic.

The best methods for avoiding the color mismatches are (a) to use a standard color chip that uses the same ingredients as you final paint, (b) make sure that the color chip and the final substrates are the same, and (c) and to make sure that the method by which the paints are applied are the same for both substrates. Other factors also contibute to metamerism, such as the number of pigments in the mixture, the temperature at which you observe the colors, and more.

We often use paper chips when we purchase paint from a hardware store. While this often gives us a fairly good color match, it can be shown that a person with a very discerning eye can probably see the difference in color between the paper chip and the masonry surface on which the paint is finally applied.