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Epoxy-anodizing: compatible?

I am building a prototype camera for which I want to black anodize some aluminum parts. In fabricating the parts I used a couple of different types of epoxy putty to repair some small areas. One of the puttys is impregnated with steel, the other with aluminum. Are these epoxied areas compatible with anodizing? If not, is it possible to "mask off" the areas so they are not anodized? As the repaired areas are not dimensionally critical I could "touch up" with paint later. Thank you!

Jon Oshima
Mplex - Brooklyn, New York U.S.A.
2005

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You only anodize aluminum, so the epoxy wouldn't anodize or accept any color. Best case scenario, that would be the final answer. Worst case scenario, the steel impregnated epoxy would suffer serious damage in the anodizing tank (steel parts dissolve, not sure what the effect would be on a steel impregnated epoxy) or the epoxies would be harmed by the chemicals (this would typically include sulfuric acid during anodizing, nitric acid and sodium hydroxide during cleaning). I would suspect that the aluminum impregnated epoxy would be okay (at least from the viewpoint of the aluminum) but it is possible that since the aluminum in it would be unable to conduct electricity it might dissolve a little bit also.

Probably the best and easiest way to find out would be to anodize a scrap piece first with a bit of both types of epoxies on it - this shouldn't hurt the bath at all and would tell you pretty quickly if your going to have a problem. If that isn't feasible, you can go ahead and just mask the epoxied areas, there are suppliers of masking supplies listed in the advertisers section of this website.

Good luck.

Jim Gorsich
Compton, California, USA
2005

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