Ask the Experts: Pencil Marks Begone!
by James Toogood
Q. I often sketch in light pencil and then paint over the pencil in watercolor. When the work dries, I usually have no trouble erasing most of the pencil. Recently I bought a set of watercolors in Japan, and when I tried to erase the pencil, I wasn’t able to do so. What do you think is happening?
A. Pencil marks are often a concern to watercolorists, but they need not be for a number of reasons. First, if the value of the color in your painting is darker than your pencil marks, the marks shouldn’t be visible. Pencil marks almost always simply disappear in the finished painting. Still, the more you know about your paints and the pigments in them, the easier it is to get predictable results.
The information you need should be either on the paint tube or the side of the pan of paint. Today, most watercolor manufacturers worldwide provide the pertinent information artists need to make informed choices; however, some of this information may be in the form of a code. The American Society for Testing Materials (ASTM) International has devised a standardized alfa-numeric code for artists’ paints called the color index name, which enables you to determine whether you’re actually getting the color—or pigment—you think you’re getting. Prussian blue, for example, is the manufacturer’s name generally associated with the color index name PB 27. If a manufacturer names a color “Prussian Blue” but lists a color index name other than PB 27 (or doesn’t list any color index name) then the color may not have the qualities you’ve learned to associate with the name “Prussian Blue.” On the other hand, all paints labeled PB 27 have the same pigment, so they’re far more likely to match each other in color and other qualities.
One of PB 27’s characteristics is its high staining quality. High-staining colors are not only hard to lift, but they can sometimes prevent you from erasing the pencil marks under them, essentially locking the pencil mark to the paper. Prussian blue (PB 27) is also transparent, so you may see the pencil mark under a light application of this color. On the other hand, heavier applications of this color tend to be darker than light pencil marks, so you won’t see the pencil on the finished painting.
Heavy applications of almost any watercolor can lock pencil marks to the paper, making the marks difficult or impossible to erase. Usually this is a problem only for colors with a light mass tone. (Mass tone is the appearance of an undiluted color in the pan or right out of the tube.)
Chances are, your Japanese watercolors are high staining, transparent or light in mass tone—or have some combination of these three factors. If your paints list color index names, you can check the characteristics of the pigments.
James Toogood, a signature member of the American Watercolor Society and the National Watercolor Society, teaches at the National Academy Museum and School of Fine Arts, in New York City; the Pennsylvania Academy of the Fine Arts, in Philadelphia; and Perkins Center for the Arts, in Moorestown, New Jersey.