Copper phthalocyanine (CuPc), also known as phthalocyanine blue, phthalocyanine blue, and many others, is a brilliant, crystalline synthetic blue pigment from the phthalocyanine group of dyes. Its brilliant blue is commonly used in paints and stains. It is valued for its excellent properties such as light fastness, coloring power, opacity and resistance to the effects of alkalis and acids. It looks like a blue powder that is insoluble in most solvents, including water.