Reducing the Complexity of Encoding Rule-Based Grammars

Improved pearlescent pigments are prepared by combining an aqueous, divalent metal salt solution with an aqueous solution comprising an alkali metal biphosphate or ammonium phosphate and a reducing agent. The combination of solutions yields metal acid phosphate or metal ammonium phosphate in crystalline form with a portion of the metal reduced to the free metallic state. The metal acid or ammonium phosphate crystals are plated onto the surface of mica or similar material at the time of formation in the presence of a cationic wetting agent within the aqueous reaction media.