Abstract: A low voltage anodizing process for anodic oxidation of metals in which are used: (i) an anodizing bath containing an electrolyte, an anode and a cathode; and (ii) and AC fed DC power supply for supplying pulsating DC power to the anodizing bath; the anodizing process comprising cyclicly discharging the inherent capacitance in the anodizing bath; such cyclic discharge of such inherent capacitance being accomplished by providing successive power cycles wherein each such power cycle consists of a rise portion followed by a fall portion followed by an off-time portion; and providing a shunt discharge path in electrical circuit across the anode and cathode and being external to the anodizing bath for discharging such inherent capacitance during the last part of such fall portion and all during such off-time portion of each power cycle, a significant fraction of the total anodizing current being shunted across such discharge path which is large enough to completely discharge such inherent capacitance and to empty

Abstract: Anodizing apparatus and method suitable for anodizing an aluminum part by a continuous process wherein the part is moved through adjacent processing regions to sequentially clean, anodize, rinse, reanodize, rerinse and dry same. The anodizing regions form anodizing cells wherein an unbroken anodizing current conducting envelope of electrolyte is formed around the part. In order to produce a hard anodized aluminum product, the electrolyte may be refrigerated or contain a selective additive. The selective additive may be formed of hydroxyacetic, carboxylic or hydroxydicarboxylic acids combined with an alcohol or triethanolamine. A surfactant may also be included in the electrolyte to form an oxygen holding foam around the part portion being anodized.