Layering colors is another way to create even more colors with the existing colors in your palette. You can expand the number of colors you have simply by layering them. Layering works best with transparent watercolors. You will have to really water down opaques colors for this process. To layer color, you paint over top of an already dry color. You can use the same color to deepen the color or you can use a different color to create a new color. You can't easily mix a layered color. The bottom color will glow through the top transparent color, this also creates a bit of depth to the color.
I created this chart on a quarter sheet of watercolor paper (11 x 15"). I counted the number of colors, in this palette there are 10. I drew 10 evenly spaced single lines in pencil, leaving some extra space at the bottom of the paper. Then I left a bit of space on the left and drew 10 evenly spaced vertical lines in pencil.
Using a 1/2 inch flat brush and following the pencil line with one edge of the brush, I painted a long straight horizontal line of each clean color. I allowed this to completely dry. Then I repeated the same process with each clean color painting vertical lines overlapping the already dried lines of colors. When this is dry, use an india ink pen or pencil and label each color on the ends. At the intersections of each color you will be able to see the variety of new colors you can create simply by layering the colors in your palette.