Q: What are some of the differences in blues, and which do you recommend for painting skies?
A: Since color choice is an extremely personal matter, I prefer to inform you of the most important color and handling characteristics of various blues to help you make your own decisions. One of the most versatile blues on the palette is ultramarine, a warm, transparent blue. The other transparent blues are phthalocyanine blue, Prussian blue, and manganese blue.
Cerulean blue is generally well liked for painting skies; in its genuine form, it's the only opaque blue, a quality that can be helpful for certain atmospheric effects. When creating tints, it produces an azure blue.