A New Kind of Varnish
By Ross Merrill
Q. Could you recommend a varnish for oil paintings that’s neither matte nor glossy? I’m specifically looking for a varnish that will enhance depth and value in the darker areas without the glare that’s often seen in heavily varnished paintings.
A. Natural resin varnishes that saturate the paint tend to be glossy and yellow with age. Synthetic varnishes are less glossy, but they rarely saturate the paint because of their large molecule structure, and when this happens you get a frosty, low-contrast image where the darks don’t really look dark. Several years ago, René de la Rie, head of the Scientific Research Department at the National Gallery of Art, combined the best elements of both types and developed a non-yellowing synthetic varnish with the properties of a natural resin. It’s now sold by Gamblin Oil Colors under the name “Gamvar.”
Gamvar is a two-part varnish, for which the solvent must be mixed with the solid resin the day before application, and it can be applied with a brush. I usually dilute the mixed varnish with about 20 percent mineral spirits (makes it flow better). To create a satin finish, brush the varnish on with a 2- or 3-inch-wide bristle brush (you can purchase one at Lowe's, Home Depot, etc, wash it THOUROUGHLY before using, it will remove any loose bristles). Continue brushing, first in one direction and then another, until the varnish becomes tacky. At that point, switch to a fresh, dry brush and continue brushing the surface. As the varnish dries, the fresh brush will pull up some of the surface of the varnish, leaving a nice satin surface. You may need to wipe some excess varnish from your second brush, and for this you can use a well-washed piece of old bed sheeting that’s lint free. If you use paper towels or a new cotton cloth, the brush will pick up lint, which will adhere to the varnish. (It's much easier than this sounds so be brave)
Ross Merrill is chief of conservation at the National Gallery of Art in Washington, D.C.