In this paper, an experimental examination of defects in anodization of aluminum of the industrial grade A7E is presented. A two-step method of anodizing was used in an electrolyte containing 20% wt. % sulfuric acid at 0 ° C at constant voltage. Micro-video recording was carried out in both anodizing stages to examine anodizing process on a micrometer scale, and to determine the corresponding macro-scale effects indicating incorrect anodization process. Macro-scale effects in the form of gas evolution were detected. Subsequently confirmed on the surface of the coating from which it occurred, using scanning electron microscopy. Methods for preparing samples subject to anodization are proposed to reduce the number of defects. The results should lead to industrial implementation of inexpensive and high-quality nanoporous anode materials with a variety of applications.