The presence of soluble salts typically results in what type of failure in coating systems?

The presence of soluble salts in a coating system leads to peeling and flaking, primarily because these salts can absorb moisture and create osmotic pressure beneath the coating. When moisture is trapped under the coating, it can cause the bond between the substrate and the coating to weaken. As the osmotic pressure builds up, it can push against the coating, resulting in the lifting or peeling away from the surface.

This phenomenon is particularly relevant in environments where steel or other metal surfaces are exposed to marine or industrial pollution, where soluble salts can accumulate. When left unaddressed, this condition not only compromises the aesthetic and protective qualities of the coating but also its long-term durability, leading to further deterioration of the substrate beneath.

Understanding this mechanism is critical for coatings inspectors, as it underscores the importance of surface preparation and salt contamination testing before applying coatings. Proper surface cleaning techniques, including the use of desalting agents or thorough wash-downs, can help mitigate this issue.