Electrochemical Methods for Determining Passivation Properties of Paint Pigments^*

Several rapid methods are available for qualitative testing of the anticorrosion properties of paint coatings. In order to gain a better understanding of the mechanism of the corrosion process under coatings, however, quantitative electrochemical methods have been devised. One such method is based on electrode potential measurements in thin layers of water extracts of paint pigments. Another involves measurement of potential difference between painted and unpainted electrodes.

A method is also described in which capacity measurements are made on an electrical condenser consisting of the coating as the dielectric layer with the metal coated and a constant area metal plate placed over the coating as the outside layers.