This standard specifies a low-voltage test method for detecting and locating defects (pores, cracks or pop-offs) which occur in enamel coatings of corrugated and/or undulated profiles and which extend down to the metal base. The method is based on colour effects (optical method) and is suitable for the precise detection of defects and their exact position. It can be used for non-flat, more profiled shapes such as corrugated or undulated surfaces. NOTE The low-voltage test is a non-destructive test for detecting defects extending down to the metal base and, therefore, is completely different in comparison to the high-voltage test according to ISO 2746.