Metal finishing Q&As since 1989

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Anodize Color

Have received 2 significantly different color hard anodized rollers- one light & one dark in color; we have no color spec but the color is typically silver, but now is dark silver. It's supposedly the same thickness & hardness, along with the same alloy. I'm told its only the differences in the bath chemistry. Should I be concerned? Thanks.

Bill Pelligra
Eastman Kodak - Rochester, New York
2005

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We do hardcoat here.

For 40+ we ran conventional hardcoat at approx. 25 Deg F.

A few years ago we switched our Hardcoat process to a reduced temp process - around 60 Deg F, with a proprietary additive used in the bath.

The process runs well & meets all aspects of the mil-spec - we have no qualms about signing the certs, BUT, we do have some customers who do not like the almost clear anodize color that some alloys come out.

Almost all of my customers have accepted the change on color, BUT, some insist on the old dark grey / bronze color to match older in field pieces. We had to give up those jobs.

So, yes, different finishers run different hardcoat chemistry & different color results may be seen. As long as you are getting the thickness you require & it is meeting your specified tests i.e., mil spec if applicable I would be OK with it.

David A. Kraft
- Long Island City, New York
2005