• What happens when you mix primary colours?
If you mix two primary colours together, you create what is called a secondary colour. Mixing blue and red creates purple; red and yellow make orange; yellow and blue make green. The exact colour of your secondary colour depends on which red, blue, or yellow you use and the proportions in which you mix them. If you mix three primary colours together, you get a tertiary colour.

• What about black and white?
Black and white can also not be made by mixing together other colours, but as they aren't used in colour mixing to create colours, they get excluded from colour mixing or theory. If you add white to a colour you lighten it and if you add black you darken it (though some painters don't use black at all, see Colour Class 5).

• Aren't there different blues, red, and yellows?
Yes, you can buy different versions of the three primaries. For example, blues include cobalt blue, cerulean blue, ultramarine, monestial blue, and Prussian blue. For red you could use altzarin crimson or cadmium red and for yellow you could use cadmium yellow medium, cadmium yellow light, or lemon yellow. None of these can be made by mixing together other colours and are all primary colours, just different versions.

• Do you get warm and cool primary colours?
Generally, reds and yellows are considered warm colours and blue a cool colour. But if you compare different reds (or yellows or blues), you'll see that there are warm and cool versions of each of these colours (relative to each other only). For example, cadmium red is definitely warmer than alizarin crimson (though alizarin crimson will always be warmer than, say, a blue).

• Why is this important?
If you mix two warms together, you'll get a warm secondary colour and, conversely, if you mix two cools together you'll get a cool secondary. For example, mixing cadmium yellow and cadmium red light creates a warm orange. If you mix lemon yellow with alizarin crimson, you get a cooler, more grey orange. Mixing secondary colours is not only about the proportions in which you mix two primary colours, but also knowing what different reds, yellows, and blues produce.

Proceed to Colour Class 2: Secondary Colours.