Pastel Q&A | Fixing a Moldy Pastel

Q. I live in a very humid climate, and I have a pastel painting framed with Plexiglas that’s developed mold. How can I remove the mold without damaging the painting?

A. Tom Komala, a pastel artist and art conservator in Denver, says, “If it’s an old or valuable painting, I’d take it to an art conservator who has knowledge of restoring works on paper. But if it were my painting, and I wanted to do my own art restoration rather than throw it away, here’s what I’d try: First, unframe the painting, removing the mat and backing board as well. Then carefully scrape off the visible moldy area. Take it outside in fresh air and direct sunlight and lay it in the sun. You don’t want to leave it there too long because the colors may fade, but there’s nothing like fresh air and sunlight to kill mold spores. Check on it every 15 minutes or so, and if the paper starts to buckle or wrinkle, bring it in at once. After no more than two or three hours, bring it back inside. Make sure there’s no trace of mold, and then carefully repaint the area where you scraped off the pigment. The painting should then be reframed, using acid-free products and putting a good spacer between the mat and the glass.

“I wouldn’t use the same Plexiglas. There’s some chance the mold spores originally came from the Plexiglas itself, which is sold with a paper covering attached with adhesive. If that adhesive got a little damp at some point, there’s a chance that the mold formed there. To prevent that in the future, store Plexiglas in a dry place, and when the adhesive-backed paper is removed, wipe the surface with alcohol and dry thoroughly.”

Even if you use Plexiglas that’s been stored properly, living in a humid climate means that mold and other problems, such as foxing (a cloud inside the glass, which can lead to mold), are more likely to occur. Artist Lorenzo Chavez had no experience with mold while living in the dry climates of New Mexico and Colorado, but when he moved to Oregon, he met a pastel artist who cautioned him against letting sunlight hit a framed pastel painting. “If there’s any moisture at all between the glass and the painting, the heat of the sunlight combines with the moisture to create foxing,” Chavez explains. “Once it’s there, you can’t get rid of the foxing without removing the glass and cleaning it. I noticed that when I took framed work outdoors to photograph it in the direct sunlight, foxing would start to occur within seconds.”

If you don’t feel comfortable handling the mold yourself, find a conservator near you by calling The American Institute for Conservation of Historic & Artistic Works at 202/452-9545 or visiting


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