What Bill is doing in the video is what he calls “conditioning.” “Conditioning” is laying in a background layer of color which will be the foundation of his painting. We’ll return to “conditioning” in a bit.

Bill is demonstrating his incredible versatility in this brief clip. He’s doing something else that is an essential principle of light in a painting.

Lots of painters get this principle wrong although it’s, as Bill would say, “common sense.”

Light travels in a straight line from the light source to the edge of a painting.

Bill sets up the light path which will guide him through the rest of the painting. He’s doing two things at once.

Bill’s “conditioning” is like what the Old Masters did with their paintings. First, they prepared their surface (or ground). Then they would lay down a color over the whole surface. Among other things, that color would set the tone or mood of the painting.

You’ll notice another thing Bill is doing. He is using the same colors that he put into the sky for his “conditioning.” That’s because the sky colors will be in all parts of your painting.

That’s why it’s often not necessary to clean all the color out of your brush. You’ll notice as you paint that your brush turns a neutral gray. Particularly when using dark colors, that neutral gray can help your other colors.

One more thing Bill is demonstrating…he’s keeping that background layer thin!

In less than a minute, Bill demonstrates four different principles and techniques. Bill was a fast painter (he had to be). It’s easy to miss what he’s explaining. That’s why we suggest folks watch his videos over and over again.