Mixing Neutral Colors
There are many purists who think you should never use a black tube of paint and that you should mix your blacks, neutrals (browns), and grays from primary colors. I do not subscribe to this principle. However, I think it is an excellent exercise to explore mixing these browns and grays. The more hands-on knowledge you have about color paint behavior, the better you will be at handling paint.
Mixing the paint in this lesson can be handled with a palette knife or a brush and a sheet of canvas from your canvas pad. You can use Cadmium Yellow, Cadmium Red, and French Ultra Marine Blue and mix straight out of the tube as shown in the illustration below. On a separate canvas sheet, try blending/mixing equal parts of each of the primary colors to achieve a black or very dark gray color. It will take a bit of back and forth, adding little bits of each primary to the black pool until you get the right balance to create the black. Once you have the center black, in the middle of the three primary colors, you can then draw it down as shown with a little Titanium White. If the black is correct, adding the white and blending down should create a range of gray as in example (a).
In example (b), you will add a little more blue to create a cooler blue black. Add the Titanium White draw-down and you will have a range of grays that are cooler with a slightly blue hue. In example (c), add a little red to the black pool creating a warmer black. Now when you do the draw-down you will have a warmer range of grays (browns).
Creating warm and cool neutral colors from the three primary colors.
Two old masters that come to mind in the use of mixing a beautiful rich range of neutral colors in their paintings are Fragonard and Rembrandt. You can see, in the examples below, the ultimate mastery of mixing neutrals from primary colors.
Jean Honore Fragonard, The Love Letter.
Rembrandt van Rijn, Self–Portrait.