UNE-EN ISO 8501-4:2021

This part of ISO 8501 specifies a series of preparation grades for steel surfaces after removal/partialremoval of water-soluble contaminants, rust, previous paint coatings and other foreign matter byhigh-pressure water jetting. The various grades are defined by written descriptions together withphotographs that are representative examples within the tolerances for each grade as described inwords. In addition, this part of ISO 8501 specifies both initial surface conditions and after-cleaning flashrust grades, also defined by written descriptions together with representative photographic examples.NOTE 1 Examples of foreign matter, other than paint residues, are salt, grime, dirt, mill scale, oil, grease andmarine growth, e.g. algae.This part of ISO 8501 relates the cleanliness of the surface to its visual appearance. In many instances,this is sufficient for the purpose but, for coatings likely to be exposed to severe environments, such aswater immersion and continuous condensation conditions, consideration should be given to testing forsoluble salts and other invisible contaminants on the visually clean surface by the physical and chemicalmethods which form the subjects of the various parts of ISO 8502.The roughness characteristics of the surface should also be considered by reference to ISO 8503,although it must be noted that preparation by high- pressure water jetting does not create a profile orsignificantly change an existing profile.