Anodizing current is prevented from being carried downstream by an aluminum web after anodizing in a continuous anodizing process. An anode is placed in a post-treatment cell containing an electrolyte which is electrically connected to a cathode in the anodizing cell via a source of DC current which is independent of the source of anodizing current. The web polarity is switched from positive to negative and a voltage greater than the exist voltage of the web is applied to prevent anodizing current from being carried downstream in the web after anodizing.
