An inorganic color pigment used in printing inks, derived from powdered lapis lazuli (or similar artificial pigment) —chemical formula Na6:8Al6Si6O24S2:4. Ultramarine Blue is a clean red blue ranging from transparent to semi-opaque, possessing high lightfastness and resistance to oils, waxes, heat, solvents, and alkalis, but which fade when in contact with dilute acids. Ultramarine Blue is primarily used in screen process printing, die-stamping, and water-based inks, although special grades can be prepared to make it suitable for lithographic printing. Ultramarine Blue is also suitable for use in the printing of food packaging, and the FDA allows it to be used in certain foods and cosmetics. (See Inorganic Color Pigments.)
('CI Pigment Blue 29 No. 77007'.)