Which cleaning standard requires white metal blast cleaning of all visible contaminants?

The correct choice is based on the standard's requirement for the highest level of surface cleanliness before applying coatings. SSPC-SP 5, also known as “White Metal Blast Cleaning,” mandates the removal of all visible contaminants and rust to achieve a surface that is essentially free of any foreign material. This level of cleanliness is critical in ensuring optimal adhesion of coatings and the longevity of protection against corrosion.

By requiring the removal of all visible contaminants, SSPC-SP 5 sets a stringent benchmark for surface preparation, addressing issues like salts, oils, and other pollutants that can impede coating performance. This is particularly important in environments subject to harsh conditions, where coatings need to perform reliably for extended periods.

In contrast, the other standards mentioned provide varying levels of cleanliness that do not require the same level of rigor. For instance, SSPC-SP 6 allows for some slight residue, and SSPC-SP 3 involves power tool cleaning that may not achieve the same level of cleanliness as SSPC-SP 5. Understanding these distinctions emphasizes the importance of selecting the appropriate cleaning standard based on the specific requirements of the coating system being utilized.