Understanding Colour.

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, yellow and blue), we can mix all other colours. Yay! That will save some money - we only need to buy three colours! But, sadly, it's not so simple - now we need to decide which pigments of red, blue and yellow to start with. What is a primary pigment? How do we pick the correct shade of (say) yellow from the huge range of yellows on sale? What are we looking for?
Well, if primary colours are the basis of all other mixed colours they must be pure, right? Meaning there should be no trace of any other colour in them. Sounds right but we all see colours differently so it will always be a slightly subjective decision limited further by the limitations of the pigments in our palettes. Crikes!