Letter 30093

Stripping sulfuric anodizing off aluminum with no dimensional loss 

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I want to know whether its possible to strip sulfuric anodizing off aluminum and don't change the dimension of the parts. If so how can it be done?

Kenneth Mullins
anodizing plating shop - Woodside, New York

No, it's not possible, Kenneth. The anodizing is not a finish that is added on top of aluminum like paint or electroplating. Rather, it is a conversion process whereby aluminum from the item combines with oxygen to form aluminum oxide. If you strip that aluminum oxide, even with zero attack on bare aluminum, the part will be smaller than when you started because some of the aluminum was consumed in generating the aluminum oxide.

For rough purposes, half of the anodizing thickness is consumed aluminum. So if you have a plate that is 1" thick and you want to anodize it on both sides to .002" anodizing thickness, it will be 1.002" thick after you anodize it and .998" thick if you strip the anodizing with no material loss. Good luck.

Ted Mooney, P.E.  finishing.com Brick, New Jersey