This International Standard specifies a method of revealing discontinuities and porosity in metallic coatings, where they penetrate the coating layer or layers down to a silver, copper or copper-alloy substrate. This method is especially useful for coatings consisting of single or combined layers of any coating that does not significantly tarnish in a reduced-sulfur atmosphere, such as gold, nickel, tin, tin-lead palladium and their alloys. This test method is designed to show whether or not the coating meets the requirement concerning an acceptable porosity level specified by the user. The value specified is usually determined by user's experience to be acceptable for the intended application. Recent reviews of porosity testing and test methods can be found in the literature [1],[2]. An ISO general guide to porosity tests for metallic and other inorganic coatings is available as ISO 10308:1995, Metallic coatings — Review of porosity tests.