Soluble salts: Their incidende on the protection of metallic structures by paint coatings

Abstract

The presence of soluble salts at the metal/paint interface is known to have a detrimental effect on the integrity of most paint systems. Though this is a long-standing problem, it has recently come to receive greater attention from the protective coatings industry. In the paper the following points are reviewed: degradation mechanisms of the metal/paint system, the role of the metallic substrate, the nature, origin and detection of soluble salts, expected levels of soluble salts in practice, critical thresholds of soluble salts and risk levels for premature failures, role of the type and thickness of paint systems and exposure conditions, and prevention measures. The author presents an overview of the subject, making reference to the related research that has been carried out by him and his coworkers over the last 16 years.