Why mixing paints doesn't produce the color
The accompanying figure represents the artist's
color wheel. Colors opposite one another are called complementary
colors. Those next to each other are adjacent colors.
A dab of paint is an opaque body. Its color is due to reflection.
No paints are pure colors; they reflect light over a narrow
wavelength band. Yellow paint reflects yellow light, but also
reflects small amounts of orange and green light, while absorbing red and
blue light. Red paint absorbs blue and yellow light, but reflects a
bit of orange. When yellow and red paints are mixed, the yellow paint
absorbs the red light and the red paint absorbs the yellow light, but they
both reflect orange. So the mixture appears orange. When two
paints mix, the color produced is the color that both paints reflect.
Add some blue paint, which absorbs orange, to the red and yellow mixture and
the paint loses its hue. By mixing all your paints together, each
pigment absorbs a particular wavelength and therefore no colors are
reflected and the paint mixture appears a dark, dull gray.