Here is one of the teaching aids Mike uses in his watercolour classes.
The subject is a seaside cliff face, with a small cave entrance.
The shape of the cliff is sketched in pencil
Underwashes of mingled Prussian Blue, Cadmium Red and Yellow Ochre are painted freely into the cliff shape so that they mix and neutralise into shades of grey. A Number 10 round watercolour brush is used.
After drying, shadows are painted on, still with the Number 10. After further drying, details are painted in using a Rigger brush. Cadmium Red and Prussian Blue are used in strong concentration for details, and diluted to a transparent wash for the shadows.