A reader recently asked me to address the color of shadows. Sometimes we see shadows painted with cool blues, and sometimes we seem them painted with hot reds. But do we really see them that way?
First, let's look at the way we discern any color, shadow or otherwise. When I teach my students, I tell them that what's important is value, temperature and hue - in that order. Hue, or color, is the least important. Shadow value and temperature really "make" the sense of sunlight, or the lack thereof.
Most of us don't have any trouble understanding that shadows are dark. (In the landscape, they tend to be more of a mid-dark because of all the light bouncing into them.) But when we come to the next characteristic, temperature, we stumble.
Here's a useful law. There are rarely any "laws" in painting, but this one goes beyond being a mere rule. It's a proven fact of ocular physics. Warm light, cool shadows; cool light, warm shadows. Whatever temperature the light is, the shadows are the opposite.
But it's sometimes hard to tell what the light temperature is. It's much less difficult to determine shadow temperature. Let your eyes rove across the scene without fixing on any one point, and you can usually tell whether the shadows look warm or cool. Another trick is to crumple up a sheet of white paper, toss it at your feet, and look into the shadows created by the folds in the paper; usually they will be very distinctly bluish (cool) or yellowish (warm.)
Most often, we have warm light, especially on sunny days. Overcast days, where you may have a silvery light, you'll find shadows more yellowish.
Now here's the trick. If you really can't determine temperature, just decide - one way or the other. And stick with it, throughout the painting. Nothing destroys the illusion of reality faster than inconsistent temperature in lights and shadows.
Finally, as for hue, it doesn't really matter. If you have cool shadows, use any cool colors you wish, so long as they are definitely cooler than anything in the lights. This goes even for the "warm" glow of light reflecting into shadows.
Above is a painting I did today with our workshop, and it's a good example of color in shadows.