The objective of colour mixing in painting is to create the largest number of options from the minimum number of colours and to be able to mix the colour you want. The ability to succeed depends initially on the quality of the colour. Winsor & Newton was founded in 1832 by two artists determined to improve the range of colours available to painters and provide colours of greater permanence. Serving these aims decade after decade requires the understanding and application of colour theory by Winsor & Newton to their ranges. In this section, the practical applications of colour theory are discussed, with reference to the colour names and characteristics of the different media.

Basic colour theory For reasons of simplicity, we are taught when young that the three primary colours   - red, blue and yellow - are all that are required for colour mixing. In fact, in pigment form every colour has both a masstone and an undertone which is different to the next colour. Looking at the illustration on the right.

For example, a blue pigment will have either a red undertone or  a green undertone in comparison to another blue pigment. French Ultramarine is a red shade blue whilst Prussian blue is a green shade blue. The undertone or bias of each colour however, is relative to the next one. For example, Indanthrene Blue, is red shade in comparison to Prussian Blue, but both would be classed as green shade blues. The colour bias is often most easily seen in a tint.

So, red, blue and yellow alone are not the whole story and in fact six colours provide a wider base for colour mixing: a red with a yellow bias, a red with a blue bias, a blue with a green bias, a blue with a red bias, a yellow with a red bias and a yellow with a green bias.

                  
Applying this in practice
The hue and undertone of each colour are best  seen on the Hand Painted Colour Charts produced by Winsor & Newton. Printed tint cards can only indicate hue and undertone as closely as is possible within the limitations of the printing process. So, in practice: if an artist wants to mix green; blue and yellow are used. Using figure 1 above, the greenest or cleanest green is made by using a green shade blue and a green shade yellow.

For example, in Artists’ Water Colour, Ultramarine (Green Shade) and Cadmium Lemon. If a red shade blue, French Ultramarine and are a red shade yellow, Cadmium Yellow Deep were used instead, a dirty
green would result.