Why Do Some Paintings Look Darker When Wet?

Imagine your favorite crayon drawing. When it is dry, the paper looks fluffy and light because air fills all the tiny gaps between the wax particles. But when you lick the tip of a crayon or add water to watercolors, those gaps disappear.

Light has a hard time traveling through air because air and the solid pigment are very different. When the paint is wet, liquid binder replaces the air. Water and oil act like bridges that let light slide deeper into the painting instead of bouncing off the surface immediately.

Because the light travels further before coming back to your eyes, less bright white light reaches you directly. This makes the colors look more intense and significantly darker. It is similar to how a dark stone looks almost black when it is submerged in a pool but gray when it sits on the dry beach.