Today in Color Boot Camp class we took a look at the colors of shadows, how the colors of cast shadows are influenced the color of the object casting the shadow, and more dramatically, the light source. Here is a mandarin orange on a pink paper napkin sitting on the table, with light coming from the windows (south windows, but this is Seattle in the winter so the light is pretty much cool from all directions):

The same orange on the same napkin held against the wall, with halogen lights coming from above:

I grabbed the pinks of the napkin from the photos and placed them side by side. The top pair are the cool light area and warm shadow of the napkin in daylight (warm light from other light sources in the room is hitting the shadow –and it’s hitting the  dark side of the orange, too making it glow red)

The second pair are the warm light pink and cool bluish shadow of the napkin under halogen light.

Maybe just painters find this stuff fascinating (and useful) now, but in the eighteenth century, when people presumably wasted far less time on cat videos, Abbe Millot, a former Jesuit and the grand vicar of Lyon, in a personal letter to a friend (remember those?), wrote a lengthy, extremely well-observed, highly detailed description of the shadows in his room cast by two different windows at various times of day.  Some details sound right out of a Thiebaud painting: “a strongly coloured sort of penumbra…a double blue border on one side, and a green or red or yellow one on the other.”

This is quoted in Shadows and Enlightenment, a book about the eighteenth-century preoccupation with shadow (Millot apparently wasn’t alone in his obsession), by the late great Michael Baxandall.