An Alternative to Phthalo Blue?

Limited palette painting project

I've been asked whether a different blue could be used for a limited palette project if phtalo blue isn't a color you already have. Whether ultramarine, cobalt or cerulean blue could be substituted? It would be churlish of me to say no, even though one of the ideas behind the project was to be able to compare paintings made with identical colors, so if you don't have phthalo blue, you may substitute ultramarine.

This is the best alternative because ultramarine is also a transparent pigment with a good tinting strength. Cobalt is transparent but has a weak tinting strength, while cerulean blue is only semi-transparent, also with a weak tinting strength. The disadvantage of ultramarine blue over phtalo blue though is that it doesn't make as deep a dark on its own.

But first check you don't have phthalo blue lurking around under one of its other names, such as thalo blue, monestial blue, Winsor blue, monastral blue, phthalocyanine blue, intense blue, Old Holland blue, or Rembrandt blue. (These names are all listed on the profile page for phthalo blue.) Check the label to see if the tube contains PB 15, and then you've phthalo blue.

See Also:
How to Test if a Paint Color is Opaque or Transparent
Color Mixing Tips
Ultramarine: The Most Expensive Pigment Ever

Image: © Edgar Coudal