Types of Chromate Pigments

The principal chromate-based pigments are basic zinc potassium chromate (also known as zinc yellow or zinc chrome), strontium chromate, and zinc tetroxychromate. Other chromate pigments exist, such as barium chromate, barium potassium chromate. 

Zinc potassium chromate is the product of inhibitive reactions among potassium dichromate, zinc oxide, and sulfuric acid. Zinc chromates are effective inhibitors even at relatively low loading levels [23]. 

Strontium chromate, the most expensive chromate inhibitor, is mainly used on aluminium. It is used in the aviation and coil-coating industries because of its effectiveness at very low loadings. 

Zinc tetroxychromate, or basic zinc chromate, is commonly used in the manufacture of two-package polyvinyl butyryl (PVB) wash primers. These consist of phosphoric acid and zinc tetroxychromate dispersed in a solution of PVB in alcohol. These etch primers, as they are known, are used to passivate steel, galvanized steel, and aluminium surfaces, improving the adhesion of subsequent coatings. They tend to be low in solids and are applied at fairly low film thicknesses [23]. 

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