Q. I paint intermittently with watercolors and experiment with different brands of paper, which means I have a lot of paper that’s been sitting around for years. What are the best ways to store it?
A. All papers are quite absorbent, so they’ll collect and expel atmospheric moisture continuously. Moreover, some papers can turn yellow and brittle as they’re exposed to atmospheric acidity (caused by air pollution, etc.). Watercolor paper in particular can be vulnerable to decay, especially when exposed to damp conditions: It’s usually sized to make it a bit less absorbent, so it can withstand copious applications of water-based paints without the uncontrollable spreading of the colors. But the sizing materials can encourage the growth of mold and attract insects such as silverfish.
If you can afford it, one of the best storage containers for watercolor paper is a metal flat file, like the kind architects use to store plans. The files cost up to several hundred dollars. If you use one, the storage room temperature and humidity ought to be fairly steady, at about 70 degrees Fahrenheit and about 50-60 percent relative humidity.
The next best thing is probably an enclosed archival storage box, called a portfolio box, typically used for storing photographs, prints or drawings. (Light Impressions, a catalog for photographic, conservation and framing supplies, sells them for between $20 and $80; call 800/828-6216 to request a catalog.) Alternatively, you can make your own archival box out of 6- or 8-ply museum board and gummed linen tape from an art supply or frame shop.
Mark Gottsegen is an associate professor of art at the University of North Carolina at Greensboro and the author of The Painter’s Handbook (Watson-Guptill Publications).