Taking Prussian blue (which is a dark blue when used as squeezed from a paint tube and quite transparent when diluted with water or glazing medium) I painted in shadows that occur in front of a wave (Photo 3). The sea in front of the wave was to be fairly flat, but full of ripples and small bits of foam.
Next I painted a dark shadow at the base of the wave, pulling it up into the wave a little (Photo 4). I then used leftover paint on my brush to create shadows underneath where I would be painting the white foam created as the wave broke. The reason for using a brush with hardly any on paint on it was that this shadow wants to be thin and transparent, not solid color.
