Sycamore sketch, 6x9, oil - $70 - contact Michael
Some of my students will ask me exactly what I mixed to get a certain color. They want a recipe - a rote multiplication table, if you will - that will tell them two dollops of ultramarine blue, one dollop of cadmium red light and three dollops of white will yield a particular grey. What I prefer to tell them, and what I want them to learn, is the concept of mixing color. If you use a split-primary palette, it's easy to cool, warm and grey colors by moving logically around the color wheel.
Here's my palette, arranged as a color wheel. You'll note that it's not strictly split-primary. Where I would have had a blue with more green in it, such as Cobalt or Phthalo Blue, I have substituted Phthalo Green. (In the image, it looks more like Viridian!) This is because to my eye, Cobalt Blue is too similar to Ultramarine Blue, and I wanted something with an even warmer cast. Also, the Cadmium Yellow Deep has so much red in it, it almost looks like an orange.
If I take, for example, Cadmium Red and want to cool it, I'll shift in the cool direction and add Alizarin Crimson. If I want to warm it, I'll shift in the warm direction and add Cadmium Yellow Deep. The same principle goes for any color mixture. (By the way, you can also add white to cool, but it also will grey the color.) It's a very simple principle and one of the beauties of this limited palette.
The little sketch above was done mostly with reds, cooled and warmed by moving around the color wheel.