Phthalo Blue is a deep greenish blue. A necessary standard dark blue used by artists, it should be used with restraint as it is very easy to put too much into a mixture.; Sennelier gathers only the finest organic and inorganic pigments from around the world. These pure pigments are ground very slowly with extreme care to an extra-fine consistency. They are then combined at maximum concentration with an archival safflower oil to yield the highest possible tinting strength and a rich satin finish. This paint has a unique buttery texture.