Growing Old With Your Paper

Q. Your article on Mary Cassatt (March 2000) mentioned that the blue paper she used for her pastels has faded to a tan or gold hue because the dye wasn’t lightfast. Could this have been caused by the paper’s acid content? In general, is it safe to use pastels on acidic paper or paper labeled “fugitive?”
Douglas A. Fales
Westmount, Quebec

A. The coloring materials used to make many blue, gray and green papers in the 19th century were not lightfast, and their fading over the years has left the paper colorless. But the paper’s fiber was often poor quality, wood-pulp-based cellulose that discolored to brown or gold as it became more acidic with age, so the discoloration of Cassatt’s paper is probably the result of both faded coloring materials and degradation of the cellulose fibers. In fact, this is the case with most damage to 19th-century papers.

Furthermore, a change in the pastel support results in a change in the pastel itself. This is a fragile medium that’s at great risk when the support darkens and embrittles, so choose your paper carefully. Modern acidic papers and papers labeled “fugitive” both may dramatically change the appearance of your pastel paintings by allowing either the color to fade or the paper to darken. Very few colored papers on the market today are lightfast.

It’s easy to test your paper’s lightfastness by placing a small sample in a window with southern exposure for a few months and a second sample in a dark drawer. Compare the two side by side after six months, and again after one year. And don’t forget to test your pastels by the same method. Conservators and pastel manufacturers have recognized that pastels in the high values—those mixed with a lot of white—are especially vulnerable to fading and, unfortunately, some manufacturers also use fugitive dyes in their pastels. Judging your pastels should become easier, though, because the American Society for Testing and Materials is currently testing the lightfastness of pastels in order to develop a lightfastness rating standard.

Mark Gottsegen is an associate professor of art at the University of North Carolina at Greensboro.

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