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Dichromate Dipping Aluminum

2004

Hi there,

As an Aluminum Foundry/Fab/Powdercoat Plant we have had a recent request from local builders for aluminum parts that have been through a dichromate bath, but have not yet been powder coated. I believe they wish to paint the parts on site. My question is whether or not aluminum that has been through a dichromate bath is safe to be handled. I.e. Can we just send it off to the builders as is. Also, is there any maximum period of time from when it goes through the dichromate bath to when it should be painted? I have heard 6 months, but am unsure. If anyone could help that would be fantastic.

Cheers,

Gordon Davenport
Aluminum Foundry/Fabrication - New Plymouth, Taranaki, New Zealand

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2004

There are all manner of parts in consumers' hands that are bare dichromated aluminum or bare dichromated zinc plating, so the hazard, if any, is minor. Still, the whole world is moving away from dichromates, so what is acceptable today may well be unacceptable tomorrow.

That being said, industrial workers should be wearing gloves, not going bare handed, and in-process parts should not be handled bare handed. If an administrative assistant is asked to put a half dozen finished parts on a conference room table, perhaps no need for gloves; but if a shipping clerk is handling dozens or hundreds of finished parts every day, gloves are needed; likewise if a factory worker is moving even one in-process part from one bin to another, gloves are needed. Just one opinion.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey