Patent ID: 8425692

Claim:
A composition for forming a protective coating on a metal surface, wherein the composition comprises water; Cr 2 (GF 6 ) 3 in which G is a Group IV-B element; and at least one polymer having a plurality of carboxylic acid groups and at least one polymer having a plurality of hydroxyl groups, and/or at least one polymer having a plurality of both carboxylic acid and hydroxyl groups; wherein the composition contains less than 500 ppm of alkali metal ions and less than 200 ppm of halide ions relative to chromium; and wherein the composition contains one or more contaminating ions and each of said one or more contaminating ions is present at less than 1000 ppm relative to chromium, and wherein said one or more contaminating ions are ions that are not part of the canonical formula of Cr 2 (GF 6 ) 3 .