Colour Mixing
A. Mixing light is additive colour mixing
Isaac Newton was the first scientist who demonstrated the effects of mixing light in the colour spectrum. By using a prism, he determined that white light in fact contains many colours. By adding the primary colours of red, green, and blue together, one can obtain all the colours in the light spectrum.
B. Mixing paint is subtractive colour mixing
Subtractive colour mixing is more readily found in nature. It is called thus because the “component primaries each subtract a portion of incident light, keeping that portion from reaching your eye” (Sekuler and Blake, 275). With paint, each ink will contain pigments that selectively absorb a certain wavelength of light, creating the colour that one views in the eye. If one were to mix two colours, like blue and yellow, the mixture will contain a combination of pigments. Therefore, “the yellow pigment in the mixture will absorb part of the light that otherwise would have been reflected by the blue pigment” (Sekuler and Blake, 275) and vice versa. In this manner, one views the colour green. This is demonstrated in the example below.
We can also compare the different colour wheels for light and for pigments.
