Primary, secondary and complementary colors

The color is a three-dimensional size and the classical color wheel is not sufficient to represent the entire color space. However, to explain the concepts of primary, secondary and complementary colors it is, probably, the best tool we can use. In painting, primary colors are those that can not get from mixing of other colors. The primary colors are yellow, blue and red. Look at the three central colors in the figure below.

Mixing two primary colors we get the secondary colors.

yellow + red = orange
yellow + blue = green
red + blue = purple

The above figure shows how each pair of primary colors produces a secondary color. We got the 6 basic colors of our color wheel which combined with black and white, are the only colors available in nature. All other colors are simply a brighter, duller, lighter or darker version of these colors.

Mixing a secondary with the next primary we get a tertiary color. For example:

yellow + green = yellow green
yellow + orange = yellow orange
orange + red = orange red
red + violet = purple violet
blue + green = blue green
violet + blue = purple blue violet

The complementary color of a given color is the opposite on the color wheel. Looking at the figure below it is easy to establish that:

• The complementary color of yellow is purple, and vice versa;
• The complementary color of red is green and vice versa;
• The complementary color of blue is orange, and vice versa.

Following the same rule, the complementary of a yellow-orange color is a blue-violet. The concept of complementary color is crucial in painting.

But why is it so important?

Using the complementary color you can control the saturation of a color. So if you have a cadmium yellow light and you want to get a duller version of that color (maybe because you want to paint the sand), mix this color with a little purple. If you have a red object, such as an apple, the color of shadow side can be get mixing the red with a little green.