The ISO 8502-9:2020 standard "Preparation of steel substrates before painting and related products, Test for assessment of surface cleanliness, Part 9: Field method for the determination of water-soluble salts by Conductivity detector" describes a field method for assessing the total amount of water-soluble salts on the surface of steel. These salt contaminants may affect the performance of coatings, such as causing corrosion and blistering. This standard applies to the assessment of surface cleanliness before and after painting, by measuring electrolysis-forming contaminants in water. Method The content of summary salts is determined by Conductivity detector, although small amounts of contaminants that are not easily dissolved are not evaluated. ISO 8502-9:2020 cancels and replaces the 1998 edition. Measuring methods such as direct sampling are added, and diagrams and connections to the Miscellaneous ISO standard are improved.