This document specifies a field method for the assessment of the surface density of various water-soluble salts on steel surfaces, before and/or after surface preparation, by conductometric determination. The individual surface densities of the salt composition like chlorides, sulphates, sodium, etc, cannot be determined by this method. This method assesses only contaminants that forms an electrolyte (ions) when in contact with water. These represent the greater part of the contaminants.