Oil Pastels Over Acrylics

Q. I work on paper by first covering the surface with acrylics, and then using oil pastels on top. Sometimes I use a touch of thinner to smooth the oil pastels. Is there anything objectionable about this process in terms of longevity?

A. The oil pastels will probably adhere to the acrylic paint without a problem, but there are some issues to consider. First, the nondrying oil in the pastels may migrate into the acrylic paint film and/or paper over time, leaving a stain. The painting will also collect dust since it’s made with nondrying oil, and must be framed under glass. Finally, if you stack paintings on top of each other for storage, they should be separated with release sheets or they’ll stick together—especially if the storeroom is hot. There are silicone papers used in the baking industry that are good for this purpose; the name will vary depending on the paper supplier.

Instead of layering oil pastels over acrylics, you might try one of the numerous acrylic paint additives that can modify the consistency, transparency, and handling of the paint. I suspect that some experimentation with these materials will allow you to achieve the same effect you get from oil pastels, but with more permanent results.

A signature member of the National Watercolor Society, Watercolor West and the Rocky Mountain National Watermedia Society, Catherine Anderson lives in Glen Ellen, California. Visit her Web site at www.catherineanderson.net.