An abbreviation used in the classification of printing inks which stands for "phosphoric, molybdic, tungstic acid." PMTA color pigments are produced by combining the original dyestuff with "triple salts" of these three acids. Many pigments are also produced from "double salts" containing phosphoric acid and molybdic acid salts (PMA), phosphoric acid and tungstic acid salts (PTA), or a silicomolybdic acid salt (SM) alone. (See PMTA Pink, PMTA Greens, PMTA Victoria Blue, and PMTA Rhodamine.)
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