Why use a limited number of colours?
There are a couple of good reasons for using just a few colours to make a quick sketch. Firstly, by using just two or three colours to mix all the colours we want we will ensure that our painting has colour harmony. It is very easy to create a spotty jigsaw of a painting by adding in lots of random colours from a paintbox, especially when we are painting in a hurry! By limiting the colours we avoid creating a mess.
Secondly, we can paint faster when we are not so concerned about getting exactly the right colours. The sketches below were painted quickly with few colours, and yet still capture the mood and feel of the scene. Sometimes this is all that is necessary in a sketch.
Paint with just two colours
Choose two colours that will compliment each other such as here in this sketch.
I painted this view in a matter of 5 minutes, just using two colours: raw sienna and cerulean blue. Note how the colours produced range from pale to dark - the dark paint being almost straight from the tube with no water added.
Click on the picture for a larger version.
Colour mixing with three colours
You will be amazed at how many colours you can create by mixing just three primaries together. Here I used cadmium yellow, burnt sienna ( a red brown), and ultramarine blue (middle row and top row). By mixing them in various combinations it was easy to get yellow ochre, dark green, dark brown, blue-black, orange and pale green (bottom row).
Paint with three colours
I used the colours above to paint this painting on site in Spain.
Click on the picture to see it in a larger version.