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Medical parts need selective re-anodizing after laser etch

We have a series of close tolerance parts that are first laser etched then anodized. The parts are machined from 6061-T6. We recently received a batch of parts in which some of the laser etching was incomplete, but have already been anodized. We have to add the missing laser etching to the surface. Does anyone have any experience with the effects of this on the anodized surface? Is there a way to come back and "reseal" the surface locally?

Any other options would be appreciated.

Phil Ryan
Medical device manufacturer - Memphis, Tennessee, USA
2003

Theoretically yes you can re anodize, practically it has been done many times, however, many "ifs".

If the original anodizing was perfectly sealed(and passes a severe seal test), you can anodize the new raw surfaces without any harm to the other finished surfaces.

Begin by cleaning the organic soil off the new raw surfaces with Q-tips ⇦ this on eBay or Amazon [affil links] and alcohol. Rinse. Deox with a Q-tip dipped in a solution of 6 oz/gal Ferric sulphate. Rinse. ,Anodize, if the original was properly sealed you have an adjoining oxide film which can be dyed and/or sealed in boiling water.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2003