Metal finishing Q&As since 1989

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Effects of local removal of anodize finish

I'm in the process of assembling a set of instruments for use in a hospital OR. The sterilization case we've chosen is aluminum, clear-coat anodized. What is the full function of such an anodized surface in this case? Does it have an effect on the cleanability or sterilizability of the case? Without it, is the metal surface pourous and able to harbor bacteria? The reason I ask - since we've received these cases, several local burrs and sharp edges have been noticed. Since they are not extensive, I'd like to remove them, but want to be assured that I understand the full reasons for this process and the effects of its removal.

Cristy
medical device - Eatontown, New Jersey
2004

Ed. note: Full name please, Cristy.

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"Anodizing" as it comes out of the tank is Porous Aluminum Oxide, the pores being microscopic, connical larger at the surface,and thousands per square inch. The aluminum surface has been converted to "Aluminum Oxide". The processer then "seals" the pores by converting the inside of the pore to "Hydrated Aluminum Oxide", which is theoretically insert to hot water baths and now pore free. However, any sloppiness in the sealing process and the pores remain open and a place for germs to catch. I would not want you poking around inside my body with an old anodized aluminum tool that had been hot water boiled many times !

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2004

I am actually concerned about the sterilization case for holding the instruments. Before any procedure, it (and its contents) is steam sterilized at 132degC for about 7 minutes. Would the steam sterilization have a similar effect on the anodized finish as the hot water bath - sealing the pores? In regions where the annodized surface is scratched, my concern is that it is able to be sterilized.

Cristy Richards
- Eatontown, NJ
2004