colour

Colour has always fascinated me from an early age and I feel that I will never stop learning more about it. I see colour as a thing of beauty in the real world, the music of vision. Nature is awash with colour, providing it or so it seems for our benefit. It has always struck me as peculiar that very few mammals have the ability to see colour yet insects, birds and fish do. We delight in immersing ourselves in colour for our own pleasure so we select the colour of our clothes, our homes, our pets and even breed plants with colours that do not exist in nature.

Additive Colours These are obtained by mixing coloured light. The TV or computer monitor screen has thousands of red, blue and green phosphors on the surface. When activated they emit the corresponding coloured light. Our eyes percieve the combination of red and green as yellow. The other secondary colours are magenta, a kind of purple and cyan, a blue colour. Mix all three primary colours together and surprisingly we get white. But then if white sunlight falls on a prism or falling rain we get a spectrum or rainbow because the sunlight is separated to give its respective colours. See our eyes and colour vision.

Subtractive Colours

When paints are mixed we get secondary or tertiary colours according to the subtractive colour system. The diagram opposite shows the primary colours, red, blue and yellow and the secondary colours, green, purple and orange. Only one tertiary colour, black is shown. The eye is capable of distinguishing 16 million colours so there are many possible mixtures other than the ones shown here. Mixtures with white are known as tints and mixtures with black are shades.

Mixing Paint

If we investigate the mixing of primary and secondary colours we find that the three primaries mixed give black (or dark grey). A primary colour mixed with the secondary colour that is produced by mixing the other two primary colours also gives black as you would expect.

	The colour patches top left show the effect of mixing a warm (orange) red with a warm (orange) yellow to get a clean orange because the red, yellow and underlying orange reinforce each other. When however a cool (bluish) red is mixed with a cool (greenish) yellow, the red and yellow still give orange but the blue tinge with yellow gives grey and the green tinge with red also gives grey. The resultant is a brownish orange.
	Likewise a cool (green) blue mixed with a cool (green) yellow gives a clean green (top) but a warm (red) blue and a warm (orange) yellow gives a brownish green because the red tinge and yellow give grey and the orange tinge and blue give grey (bottom).
	Here a cool (blue) red mixed with a warm (red) blue gives a clean purple. A warm (orange) red mixed with a cool (green) blue gives a greyed purple as the orange and green components produce grey with blue and red.
	The colourwheel shows the relationship of contrasting colours, opposite each other on the wheel and harmonising colours, adjacent to each other. Yellow is opposite violet, mixed together as paint they will produce grey. Yellow is flanked by lime green and chrome yellow, harmonising colours.