We arrange our oil color tubes on a rotating circular tray that has two tiers. The tray serves several functions. First a rotating tray gives us ready access to all the tubes without having to rummage around in a paint box. We use many colors for every painting—sometimes only tiny amounts from each—and we don’t want to compromise our range of color out of impatience with finding a tube. Second, we have arranged the oils in the order of a typical color wheel, across the color spectrum from yellow to violet. There is a photo of our double-layered paint tray under the section called “Painting with Knives”. The tray is made of a lazy susan with circular pieces of thin plywood on top to extend the surface. The top layer is a piece of scrap carpet that keeps the tubes from sliding around. Hanging above the tubes of paint we have two color wheels that correspond to all the colors on the tray. See photographs of them on the left. The wheels enable us to get a quick idea of the distance on the color spectrum of each tube of color. The proximity of two colors on the spectrum is very important because the closer two colors are on the spectrum the more brilliance will be retained in the result. Mixing colors that are across from one another on the spectrum will dull the brilliance “desaturate” the resulting color. Finally, the two-tier system enables us to separate the earth colors from the others. Earth colors, so-called because they are compounds of iron, are arranged on the upper tray while all the other colors are arranged on the lower tray. By separating our oil colors into these two collections we can more easily maintain the “fat over lean” rule of oil painting. The earth colors, by and large are “leaner” (they absorb less oil) than the others. When possible leaner colors should be laid down first. Moreover, the earth colors are less saturated (brilliant) than the other colors and dry more quickly. The saturation or brilliance of a pigment is very important because it enables us to create the illusion of depth and lighting effects by using the desaturated colors in the depth or shadows and more brilliant colors for the highlights or lighted areas.