Where the
world gathers for metal finishing
Q&As since 1989


-----

Glass in anodising process

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 fluoride 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
- Navarre, Florida
2006

---

2006

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, North Carolina