1.1 This International Standard specifies general methods of measuring the ductility of metallic coatings of thickness below 200 μm prepared by electroplating, autocatalytic deposition or other processes (see the note). The methods of measuring the ductility of metallic coatings can be divided into two main categories : — tests on unsupported foils (separated from the substrate); — tests of coatings on substrates. NOTE — When specific methods of testing are included in International Standards for individual coatings, they should be used in preference to the methods described in this International Standard and should be agreed upon beforehand by the supplier and the purchaser. 1.2 In the testing of unsupported foils separated from the substrate (see figure 1), the foils may consist of one or more metallic layers. Therefore it is possible to measure the ductility of composites and to determine the influence of individual layers on overall ductility. Methods of testing of unsupported foils are described in clause 3. Methods of producing foils for testing are discussed in annex A. 1.3 In the testing of coatings on substrates (see figure 2), it is especially important to determine the exact point of crack initiation of the top layer. Attention is drawn to different methods of discerning this point, by normal or corrected-tonormal vision or with a lens. See the guidance in the individual methods. These methods can also be used to detect embrittlement of the substrate that may have resulted from the coating process. Methods of testing of coatings on substrates are described in clause 4. 1.4 Although ductility is a property of the material and independent of the dimensions of the test piece, thickness of the coating may have an influence on the value of linear elongation (Δl/l0). 1.4.1 Very thin layers have different properties as the build-up of the initial layers will be influenced by the properties of the substrate (epitaxy). High internal stresses may be incorporated into the initial layers and these may affect ductility. 1.4.2 It is essential that the test piece has uniform thickness, as thinner spots will give rise to premature cracking. Also, the current density is lower at thinner parts and higher at thicker parts of electroplated test pieces; in this way current density differences may result in different ductilities. The current density applied should be maintained as uniform as possible over the test piece, and its value reported.