Q. How do the alternatives to wood supports—MDF board and Masonite—compare? Can you tell me the pros and cons of each type?
A. Both materials can perform well as painting supports if properly prepared. Masonite, a brand name for hardboard, comes in both tempered and untempered versions: The tempered type contains an oil or resin to make it harder and more moisture-resistant than untempered hardboard. Either can be used, as long as the surfaces are lightly sanded to provide good adhesion between the support and a layer of primer. Ive used tempered hardboard for years as a support for both traditional glue-gesso grounds and acrylic emulsion grounds, and have experienced no problems of delamination or other deterioration.
Medium density fiberboard (MDF) is a thicker material thats less dense than hardboard. It, too, can be used as a support—with one caveat. A conservation scientist reported to me that hes seen one case where formaldehyde-containing MDF had caused efflorescence (a powdering on the surface) in an apparent reaction with an acrylic emulsion ground. Formaldehyde is used to provide water-resistance; MDF edges are very porous to moisture and can swell in damp conditions. I would recommend that you try to find formaldehyde-free MDF and apply several coats of primer to its edges.
In sizes larger than about a foot on one side for the hardboard and about 18 inches for MDF, both materials can warp due to the differences in tension between the painted and unpainted surfaces. Up to a point, this warping can be countered by putting a ground and a layer of paint on both sides of the panel. Better, though, is to apply perimeter and cross bracing to the rear of the panel. Use 1×2-inch lumber and a good quality wood glue, then clamp the braces in place overnight. Of course, a large, braced panel of either type of support can be very heavy. If this troubles you, you might want to restrict your use of the panels to small paintings.
Trained in Russia, artist and instructor Andre Kohn lives in Scottsdale, Arizona.