Q. The snow in some of my landscapes has turned a yellowish color. Why does this happen and what can I do about it?
North Pole, AK
A. Without knowing specifically what materials you used in your painting, its difficult for me to say what caused the yellowing of the snow in your landscapes. But there are a few possibilities. First, remember that it isnt uncommon for oil paints to yellow with age. Second, white lead paint is notorious for yellowing, especially if the painting is stored in the dark. If the cause is white lead, then exposing the picture to bright sunlight for a few days will usually correct the problem. Keep in mind that it will yellow again if stored for a long period in the dark. Another cause for yellowing may be the varnish on the painting. Natural resin varnishes–such as damar–yellow with age and the change in color will be most noticeable in the white snow rather than the darker colors. If the yellowing is from the discoloration of the varnish, theres no solution short of having a painting conservator remove the varnish.
Ross Merrill is chief of conservation at the National Gallery of Art in Washington, D.C.