This part of IEC 62321 describes a boiling water extraction procedure intended to provide a qualitative determination of the presence of hexavalent chromium (Cr(VI)) in colourless and coloured corrosion-protection coatings on metallic samples.
Due to its highly reactive nature, the concentration of Cr(VI) in a corrosion-protection coating can change drastically with time and storage conditions. Since storage conditions prior to sample submission are not often known or provided with the samples, this procedure
determines the presence of Cr(VI) based on the levels detected in the coatings at the time of testing. For testing of freshly coated samples, a minimum waiting period of 5 days (after the coating process) is necessary to ensure the coatings have stabilized. This waiting period allows potential post-process oxidation of Cr(III) to Cr(VI) to occur prior to testing.