Colour is the most expressive element of art and is seen by the way light reflects off of a surface. A surface hit by white light, which contains all colour wavelengths, will reflect only certain wavelengths depending on what we call the ‘colour’ of the surface. For example, if an object contains cadmium red pigment, the wavelengths reflected will only be those that are red; the rest will be absorbed within the surface/object.
Colours are divided into three main groups: Primary, Secondary and Tertiary. Theoretically, any colour can be made through a mixture of the three primary colours red, blue and yellow. The colours made by mixing two of these colours are called secondary colours; violet (blue and red), green (blue and yellow) and orange (red and yellow). Tertiary colours are further mixtures of these three colours.