Prussian Blue is similar to Phthalo Blue in that both are intense and very strong colours. Both should be used sparingly, and as a general rule use Prussian Blue where a deeper, more opaque finish is needed.; 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.