This part of ISO 8503 describes a visual and tactile method for assessing the grade of the profile which is produced by one of the abrasive blast-cleaning procedures described in ISO 8504‑2. The method uses ISO surface profile comparators for assessing, on site, the roughness of surfaces before the application of paint or other protective treatments. NOTE Where appropriate, ISO surface profile comparators can be used for assessing the roughness profile of other abrasive blast-cleaned substrates and, in addition, their use is not restricted solely to surfaces that are to be painted. The method is applicable to steel surfaces which have been blast-cleaned by use of either shot abrasives or grit abrasives, but is only applicable to grades Sa 2½ and Sa 3 of ISO 8501‑1 where the entire surface under test shows an overall blast-cleaned appearance. lt is applicable to surfaces which have been cleaned with either metallic or non-metallic abrasives.