Colored Pencil Lightfastness: An Easy Test

Let’s talk about an easy test for colored pencil lightfastness.

If you’re a fine artist—if you’re producing artwork for sale—the longevity of your art is very important. You want the artwork your collectors and clients purchase to last a long time. Nothing is more abhorrent to you than the thought that your work will fade in a few short years.

One way to make sure your artwork has a long life and looks good for years is to use the best materials available. Paper that’s proven to hold up under use and time.

Colored pencils that are high quality and lightfast.

Yes, archival papers and high quality pencils are going to cost you more, but they will be worth it in the long run—especially when compared against the possibility of having to refund a buyer for faded artwork or having to do a work over.

I’ve already written briefly about choosing paper for colored pencil work and plan to write more fully on that topic in the near future. So our topic for today is colored pencils.

Namely, about lightfastness and a simple test you can do to find out how lightfast your pencils are.

What is Lightfastness?

Lightfastness is a measurement of a pigment’s ability to resist fading or discoloration under normal circumstances. A pigment that is lightfast doesn’t fade.

The American Standard Test Measure (ASTM) rates pigments from one to five and is generally displayed in Roman Numerals (I, II, et cetera). The lower the number, the more lightfast a color is.

Oil paints display a lightfast rating on the tube. Most colored pencils do not show a lightfast rating on the pencils or even on the containers because each color has a different rating.

Other countries use other rating methods. For example, in the United Kingdom, the Blue Wool Test is used and pigments are rated from 1 to 8, with the higher numbers being the most permanent.

Colored Pencil Lightfastness

The general rule of thumb is that the higher quality pencil, the more lightfast. That’s not universal, however. Some colors manufactured to the highest artistic standards are not very lightfast. Pinks and purples are notorious for fading fairly quickly no matter what brand of pencil you use.

Many manufacturers provide color charts that indicate the lightfastness of each color they produce. Many others provide that information online, though you may have to search long and hard to find it.

Conducting Your Own Colored Pencil Lightfastness Test

So does that mean you’re at the mercy of the manufacturer?

No. There is a way to test lightfastness on your own. Here’s how I do it.

Step 1

Make a color chart for each of the colors you want to test. It doesn’t need to be neat or tidy (though it may be). Nor does it need to be complex, though you can make it as complex as you wish.

I layer color quickly and with medium or heavier pressure. As you can see from the sample shown here, my strokes are long and scribbled. My interest is in getting patches of uniform color, so I don’t worry about neatness, value, or anything else.

Label each color.

I also label the top of the sheet with the brand of pencil, the type (in this case Koh-I-Nor Progresso woodless), and the date I made the sheet.

Step 2

I covered the center part of the sheet with another sheet of paper. I’m going to put this sheet in a sunny place for a while and I want to hide part of each color swatch from the sun.

But you can also cut the sheet so that each color is cut in half, giving you two complete sets. One set is exposed to the sun, the other set is kept in a drawer or some other place where light cannot reach it.

Step 3

Wait.

At least four weeks.

Some of the colors may start to fade more quickly than that, but to get a good idea of how long-term exposure to light affects all the colors, I leave test sheets in sunny windows for at least four weeks.

I don’t play nice, either. I put test sheets like this in south facing windows where they get direct sun most of the time. It’s a good way to see how well colors perform under terrible conditions.

Step 4

After four weeks, compare the colors exposed to direct light to those not exposed to direct light. Those colors that show no change are lightfast and unlikely to fade.

For those colors that did fade—and some of them will—note how much they faded. If they faded just a little bit, you may decide to continue to use them. Keep that chart handy so you can refer to it while you draw and so you’ll know when and how you may need to compensate for those colors.

If a color faded a lot, it’s probably wise to stop using it.

Here’s my test sheet after 30 days.

Light Blue and Paris blue showed clear signs of fading. Much to my surprise, the pinks and purples showed little or no signs of fading after 30 days.

Ten Months Later

August 18, 2017

I took the test sheet out of the window, removed the protective cover,  and here’s what I saw.

Carmine and Light Blue faded badly. I will not be using them for future drawings.

Pink and Scarlet Lake faded, but not very much.

The other colors show no sign of fading.

The take away is that although these pencils come in only 24 colors, most of them are very lightfast. At least the sixteen colors I tested are reliable.

A Test For All Colored Pencil Lightfastness

This test works with all brands and grades of pencils. You can even do side-by-side comparisons of similar colors from different brands. If you use more than one brand of pencil, knowing how the colors perform relative to one another is valuable information.

Especially if the manufacturers use different methods of testing or reporting lightfastness.

For my money, even if manufacturers thoroughly test their products and report the results, doing my own, real-life tests is worth the time and effort.

You may find it’s worth your time and effort, too.

Got a question? Ask Carrie!