Pine Trees oil sketch

Pine Trees oil sketch 5″ x 8″ en plein  air.  Thirty minute study.

By adding viridian to the limited palette (Cadmium yellow pale, Alizarin Crimson, Ultramarine Blue and Titanium white) I was able to create warmer darks.  Viridian helps, not so much because it is green, but because it is a dark value green that is able to temper the combination of alizarin and ultramarine by reflecting a quantity of yellow.  When I add cadmium yellow pale to the alizarin/ultramarine mix for a dark, it simply lightens the mixture and makes it muddy.  The addition of Viridian to the palette also allows for a nice mix for the blue spruce.