Influence of inert pigments is on the anti-corrosive properties of paint films: Part 1

1. Introduction In corrosion protection it is usual to differentiate between inert and active pigments. Inert pigments are those which, according to present theories, have a mere barrier function in the film. Active pigments, on the other hand, reduce or prevent corrosion by the formation of passivating ions, as chromates do, or by the formation of metal soaps like lead, and zinc pigments. Long-term work with inert pigments in primers has shown that they, too, influence the performance of primers in a variety of ways — such obvious factors like differing water-soluble salts contents or strongly varying critical pigment volume concentrations being left out of account.