This document specifies a method for assessing the quality of sealed anodic oxidation coatings on aluminium and its alloys by measurement of the admittance. The method is applicable to anodic oxidation coatings sealed in an aqueous medium. NOTE 1 Results obtained from anodic oxidation coatings sealed by different methods@ e.g. hydrothermal sealing and cold sealing@ are not necessarily comparable. NOTE 2 Results obtained from anodic oxidation coatings on alloys containing more than 2 % silicon or 5 % manganese or 3 % magnesium are not comparable with results obtained from anodic oxidation coatings on more dilute alloys. The method is suitable for use as a production-control test and as an acceptance test where there is agreement between the anodizer and the customer. Any type of anodized component can be tested by the method described@ provided that there is a sufficient area (a circle of diameter about 20 mm) and that the film thickness is greater than 3 ??.