Colour theory is an essential reference for any artist. Most of us have a vague memory of colour wheels from our school days but apart from reminding us that yellow and blue make green, blue and red make violet, and red and yellow make orange, what use is it? First things first - the subtractive colour wheel is based on the three primary colours of red, yellow and blue. This is the colour wheel for painters and creators of things which are seen via reflected light. If all three primaries of this model come together you get, (in theory), black, (in practice mud!). Other colour models exist; you will likely be aware of the red, green, blue, additive colour wheel which works for projected light images, (on your computer for example). If these three light based colours come together they produce white light - think Dark Side of the Moon prisms! As painters we need be concerned only with the subtractive colour wheel. The theory states that from the three primary colours, (red, yello...