What in the World is a Spectrophotometer?

MOSAIC Group Guest Blogger: Tim Small, retired paint sales professional

Have you ever wanted to match a piece of wallpaper to a paint color? You go to your local paint store or home improvement center and ask them to color match the wallpaper sample. You’ll probably see a sign hanging near the matching machine that reads something to the effect of “Bring us your sample: we can match anything.”

The computer used to help complete the task is called a spectrophotometer. It measures the wavelengths in light. Using a light source, it shines light onto the sample. The sample absorbs the light. A detector then measures how much light is absorbed and converts that data into a formula.

The spectrophotometer is just a point of reference. It gives a formula that is usually close enough for most customers. But sometime it gives you a formula that you ask yourself “Where did that come from?” That’s when the skill, knowledge and eye of the paint salesperson kick in. We all know there are several color combinations to get to that matched color. The general number of colorants used to reach the target color is three.

Now, back to that sign that states “We can match anything.” While that may be true, there are some key factors to remember. The best match is going to come from a sample that is flat and has no texture. A good example is a piece of smooth wallcovering or a paint chip. The more texture the sample has, the harder it is for the computer to get a good reading.

Some of the worst samples are carpet, heavily textured wallcovering, exterior siding and masonry. Why? When the computer shoots a bright light on a smooth sample, there isn’t a problem. On a textured sample the bright light causes shadows and that is what the computer reads, causing it to give you a formula that is way too dark. If the paint person doesn’t know or remember that, then the quart or gallon of paint becomes a mistint.

I can remember matching paint by eye before the color-matching computer became popular many years ago. Sometimes completing a color match could take one to two hours. Today’s customer is on their way in several minutes.

By the way, some of the strangest things customers have brought me to color match have been a child’s water wings, a Frisbee, a plastic train locomotive, and-my favorite-pink bubblegum that had been chewed.