When examining coating surfaces, what is the primary indicator of soluble salt contamination?

The primary indicator of soluble salt contamination on coating surfaces is the presence of discoloration of paint. Soluble salts can lead to various issues in coating integrity, and their presence is often identified by visible changes in the appearance of the coating, such as discoloration. These salts can draw moisture and contribute to corrosion processes underneath the coating, leading to visual symptoms that indicate underlying issues.

Discoloration may present as dark spots or staining on the surface of the paint, which often signals the need for inspection and possible rework to remove contaminants before re-coating. Recognizing this sign can help inspectors determine if corrective actions are needed to ensure the durability and adhesion of the coating.

While blisters, filiform corrosion, and cracks can all indicate issues with the coating system, they are more typically related to other factors such as improper application techniques or environmental exposure rather than directly pointing to soluble salt contamination.