To retain the vivacity and brightness of the colour, in particular for my painting Centaurea cyanus and also for Digitalis purpurea, I did not mix my hues. When using blues, reds or violets it is best to use the hues separately rather than to mix them. If the hues are mixed, brightness in the painting will be lost and the overall result will be a dull murky colour, which will be a disappointment in the finished painting.
With watercolour, once brightness is lost it cannot be retrieved. Hues separate, instead of mixed, and placed close together or overlaid give a more lively effect and achieve vivacity. This works particularly well for the most prominent, foreground sections of a painting. Washes of pure, unmixed transparent colour can be added. I use transparent colours as much as possible for all my work.
Some examples and sketches (these are only sketches, not finished pieces!) previously used for different paintings.