Surface Preparation of Contaminated Steel Surfaces
Case histories indicate that non-visible contamination may result in rapid coating failure. Contaminants may be assumed to be presents on any steel surface. Even new steel may be contaminated at the origin or during transport or installation. Therefore, any steel surface to be coated requires cleaning followed by testing for non-visible contamination.
Non-visible contamination may be detected by allowing the just-cleaned surface to rust. If a uniform sandy rust results the surface may be free of Iron Salts and chlorides that would otherwise produce dark or black areas.
Other chemical and simple physical tests are also described and evaluated. Remediation of positive test results are discussed. Reagents, materials, tools, procedures and results are detailed.