Tip: Solving the Mystery of Shadow Colors

Photo by Lyubomir Bukov

Until recently shadows have had a negative connotation for me. After all shadows are dark and not very interesting. Its not just me either. Victor I. Stoichita, in his book called A Short History of the Shadow, states that the Greeks used shadows as a negative metaphor for psyche, or "life, spirit, and consciousness". For example, a dead person’s soul was compared to a shadow and Hades was considered the land of shadows, or the land of death. In Plato’s story about the origin of knowledge, cast shadows on cave walls kept early man from the light of truth.

It wasn't until Leonardo da Vinci that shadows began to be viewed positively, at least by artists. He and others found that shadows could be used to give the illusion of depth and perspective in two-dimensional art. Without them drawings and paintings are reduced to flat masses, lacking interest and objective realism.

Not all shadows are equal. There are in fact two very different kinds of shadows that occur in any subject, cast shadows and form shadows. A cast shadow is the darker type of shadow because it is created by the light source being blocked. It has sharper edges, especially nearest the light source. A form shadow is the shadow on a subject where the subject does not receive direct light. Form shadows have softer edges and are lighter in value than cast shadows.

Like other visual elements, shadows have a shape that must be captured but that is done primarily by calculated observation and drawing. What is more difficult is the color in shadows. I've been told that all shadows should be drawn in a shade of purple. Others say that cool light produces a warm shadow, and the warm light produces a cool shadow. I believe that a shadow's color is influenced by a variety of other factors as well, including the particulates in the air, the local color of the object itself, and the colors of adjacent objects. With so many factors to consider, what is an artist to do?

I recently read about an exhibit on display at the Pecci Milano Museum in Italy. It was organized with the help of the Laboratory of Neurobiology of the University College in London. The work was inspired by what is known and unknown about color perception, specifically the color of shadows. They placed white sculptures in white rooms and illuminated the sculptures with white light and one additional light of a different color (red for example). The result is colored shadows that we sense to be of the complementary color (in this instance green). Everyday examples include blue-purple shadows caused by the orange-red setting sun and the violet shadow behind the light of yellow-toned rocks. The color in these shadows is not really there but our minds perceive the color.

Although more subtle, shadow colors are also influenced by indirect and reflected light. There are two sources of reflected light, those that come from the ground plane and those that come from the sky. When painting outdoors all shadows are cooled slightly by the color of the sky. Similarly, you may see reflected ground colors in shadows as well. The stronger the light source and the more perpendicular the reflecting object is to the plane of the shadow, the more the shadow will be affected by its color. This is why we often see warm colors in shadows that are created by a warm light source.