Good colors for demonstrating color theory or making a color wheel are as follows: Yellow; Hansa Yellow Light #107 or Azo Yellow Medium #144. Red; Quinacridone Red #129 or Quinacridone Magenta #147 Blue; Phthalo Blue #115 or #115-D or Ultramarine Blue #122. Transparent colors tend to give cleaner, brighter mixes than do opaque colors. Opaque colors such as cadmiums, cobalt, and most oxides tend to make dull secondary colors when mixed with each other. Opaque colors are more brilliant when mixed with transparent colors. Check your label or color chart for “opaque” or “transparent” identification.