Hue No. 03
Here I learned opaques work better for these paintings. They provide a more solid color. In the bottom left, the ultramarine violet square is not as solid feeling as the others. Titanium white paint is an opaque and the square next to the pure ultramarine violet one is mixed with a bit of titanium white. That square looks a bit more solid and as the squares get lighter, as more white is added, they feel more solid.
Hue No. 03