Many art students learn how to mix their paints by looking at a layout similar to the one above. It was how I first started. What is intended to take place in the center of this wheel, its spokes if you will, are the various mixtures. I realized later that I was actually looking at just two dimensions of color, hue and chroma. Hue being the color label (i.e. red, yellow, blue-green, etc.) and chroma being how much hue is present, or what Albert Munsell called the color’s strength. Unfortunately, those students are not getting the whole story.
What becomes immediately apparent is that many of the pigments I have don’t appear on this wheel. Where’s burnt umber, or for that matter, black and white? Why are so many of my paints much darker than these on the wheel? What I discovered is I wasn’t looking at a wheel but a CYLINDER. Turn it on its side and you see it has another dimension, value. Now I can more easily figure out where my paint color sits in true color space.
There’s a fourth trait that paints have, however, beyond color alone, and that’s how opaque they are. This is a physical property pigments have that cannot be described on a color wheel, and it is critical to understand. Paints have to be used in combination figure out how the pigment behaves. It’s their fourth dimension (Eeeek! Dum-Dum-Duuum!)
Many paint companies use an icon that shows how opaque the paint is. They’re not all the same, however, and sometimes what they call opaque isn’t very. The best way to determine this is to put them to use and test them out. Add white to see what tints of the color look like, paint undiluted layers over darker and lighter value paints, scrape layers across white paper to examine their quality, and of course test them in various mixtures. This will help you determine where they sit on the “cylinder” model. I always do this with new paint.
A limited palette is very practical for painters, but if you cut it down too far you won’t be able to mix all the colors you may need. If you find yourself frustrated with how poorly your mixes turn out, it’s likely the fault of your color selection. Fit your pigments within the color “cylinder” as best you can to determine where the gaps are. I like having colors that straddle both sides of the color fence. For example, I prefer having different blues that are somewhat reddish or greenish, as well as having slightly different values. It offers me the most flexibility, even if I rarely use them all.
Books for further study:
Color Notation: An Illustrated System by Albert H. Munsell
Color Studies by Edith Anderson Feisner
Power Color by Caroline Jasper