Abstract
It was proved by many researchers that both alkaline and acid electro polishing of aluminum are possible. But the acid polishing method, or acid bath system, has been mostly popular, for the effect of the alkaline bath has been limited to a highly pure aluminum, the throwing power is low and the bathing control is difficult. However, if the electro polishing in alkaline bath is not the final process, satisfactory results can be expected. For example, if buffing and soak cleaning (or an electrolytic cleaning) are adoped instead of alkaline electro polishing, the process becomes simple. Especially, in the case of small or complex articles, the alkaline electro polishing method mentioned above can be adopted as pre-treatment of phosphoric acid type electro polishing or anodizing, leaving the articles on the rack as they are.
Bath composition suitable for electro polishing as pre-treatment was investigated and an electro polishing bath outstanding both in speed and effect was developed, with caustic soda as principal ing-redient, and sodium-phosphate, sodium-carbonate, glauber's salt and other weak acid alkaline salt as inhibitor.
