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Can chromating be used and look like mill finished or anodized aluminium?

April 13, 2011

I am wanting to get a boxed aluminium gate frame coated in something other than
powdercoating it with a colour. I live close to the ocean and would need to coat treat or
cover the mill finished aluminium. However I do not want to loose either the shine of
polished aluminium or the matte finish of anodized aluminium. Anodizing is out of the question because of the size. Could chromating come to the rescue in a clear or gloss finish? And would I still have to coat the frame in a clear powdercoat?
Thank you for sharing your expert advice with lay people.

Kind regards
Martin Sebastian

Martin Sebastian
Renovator - Brisbane Queensland Australia

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I would go with powder coating, especially due to your locale with the potential salt corrosion. It would last much longer than a clear chromate/Alodine conversion coating, and also be much less susceptible to scratches. Any reputable powder coating outfit should be able to offer you a "clear" coating.

Marc Green
anodizer - Boise, Idaho
First of two simultaneous responses -- April 15, 2011

According to one expired USA patent (and some Japanese patents too) tanin/potassium titanium fluoride solutions can be used instead of carcinogenic chromium compounds (USPT 4,045,466 - www.uspto.gov):1 gm tannin/0,003 gm potassium titanium fluoride/1 lit water solution heated to 50 °C must be applied to object and rinsed after 30 seconds. After that step you must clearcoat your object. Hope it helps and good luck!

Goran Budija
- Zagreb,Croatia
Second of two simultaneous responses -- April 15, 2011