This part of ISO 8502 describes a method of extracting, for analysis, water soluble contaminants from a surface by use of flexible cells in the form of adhesive patches or sleeves which can be attached to any surface, regardless of its shape (flat or curved) and its orientation (facing in any direction, including downwards). The method described is suitable for use in the field to determine the presence of water soluble contaminants before painting or a similar treatment. This part of ISO 8502 does not cover the subsequent analysis of the contaminants that have been dissolved off. Methods of analysis suitable for field use are described in other parts of ISO 8502. NOTE The extraction method might give a false negative or not take all the water-soluble material off the surface because of: (1) Soluble materials hiding in the crevices or under folds of metal; (2) Soluble materials under corrosion layers, passivation layers produced by corrosion inhibitors, oil, grease, or other non-visible thin films.