No, it’s just the morning sun hitting our jars of dry pigments through the blinds, a brief exposure that does no harm. Our paintings conservator uses the pigments to mix up retouching paint.
On a palette, the dry powders are added to a clear, liquified, daub of acrylic resin. Then the paint is mixed with a fine brush and thinned to the right consistency using solvents. With this technique, each paint is a precise color match to the area to be inpainted.
The conservation-grade resin has been tested extensively. It fulfills two key criteria in the practice of paintings conservation: It is easily identifiable as non-original on an oil or tempera painting, and it will be easily removable in the future. The resin is also very stable, meaning it should not yellow over time.
Our supply of dry pigments will last a very long time. The jars shown here, on their post-renovation shelf, have been in use at the museum for decades!