Letter 42079

Glass in anodising process [UK] 

August 30, 2006

Hi,

I'm doing some cosmetic trials on anodising bead blasted aluminum and was wondering if there are any risks to the performance of our anodising line due to contamination from the glass.

Thanks,

John Peacey
- Gloucester, UK

I can not think of any thing other than if you use a flouride in your line, it might be consumed slightly faster. Most of any of the broken beads that are stuck in the aluminum will come off during the caustic etch step.

James Watts
- FL

Elaborating on Watt's correct answer, glass dust, glass particles, and all the contamination that is in/on the glass will imbed in the soft aluminum - therefore you MUST heavily etch to undercut the imbedded junk. The glass must not have been used on any other metal. The glass will not contaminate the anodizing solution, it will fall to the bottom, however, under some conditions of solution agitation the glass dust will "occlude" in the anodizing coating.

Work was done at NASA Huntsville in the 1960's which occluded diamond dust into hard coat anodic films.

Robert H Probert Robert H Probert Technical Services Garner, NC, USA Editor's note:        Mr. Probert is the    author of Aluminum How-To

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