This is my entry in the DPW Challenge, 'a painting to include the primary colours'. I use these pigments constantly: ultramarine blue, yellow ochre and light red oxide. I have started to replace light red oxide with terra rosa which makes some lovely pinky notes on flesh for portrait. Cerulean blue also works well to dull down the reds and makes some good greens with the yellow ochre. The title suits this study because that is what they are.