Q. Why do my watercolors appear darker when they’re wet?
A. Great question. It never fails: You’ve just painted a brilliant flower but when it dries, it looks dull. After you’ve been painting for awhile, you’ll learn how much paint to put on so that when it dries, it will be as dark as you wanted it. But no matter what you do, you’ll still lose much of the brilliancy.
But why? Honestly, I had to look this one up. Here’s what I found out: Your paper is made of cotton, just like a cotton shirt. When you dip the paper in water, it turns gray right before your eyes. What causes this optical transformation is simple science. When cotton gets wet, light coming toward it refracts within the water, dispersing the light. In addition, the surface of the water causes the light to scatter. The combination of these two effects causes less light to be reflected to your eyes, making the wet paper appear darker.
You may have noticed that the color seems to deepen once your painting is framed under glass. To help me gauge how much color intensity I’ll get back once the painting is framed, I place my work in progress under a piece of glass every once in a while after the paint starts to dry and get dull. This will bring the color up a great deal and let me see what it will look like once the painting’s framed.
Mark Gottsegen is an associate professor of art at the University of North Carolina at Greensboro.