An organic color pigment used in printing inks. PMTA Rhodamine, classed as a violet pigment, is a strong magenta commonly used as a bluish red. Although possessing high tinctorial strength, it tends to darken upon exposure to light, however, and has poor resistance to water, solvents, oils, and soaps. Although it is usable in water-based inks, it is unusable in lithographic printing, and its use is declining. Like other PMTA pigments, it is a "triple salt" of phosphotungstomolybdic acid. It is also produced from double salts, as well. (See also Organic Color Pigments.)
('CI Pigment Violet 1 No. 45170:2'.)