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Mil-C-5541, Class 1A, Type II RoHS Compliant

I have a customer requesting a Mil-C-5541, Class 1A, Type II Pretreatment process, prior to Powder Coating their parts. They also stipulate the Iridite color is Yellow, and RoHS Compliant. It seems to be a contradiction in terms. I was under the belief that the Chrome is what makes it yellow, and the Chrome which is regulated by RoHS. I have also heard that its possible to add dyes to the clear, but wouldn't that alteration present a problem with compliance to Mil- C-5541?

David Grabowski
president of finishing shop - Fridley, Minnesota
January 29, 2009

I agree, it's a Catch 22, customers are such a pain :-).

Leo Herringon
consultant - Grand Rapids, MI, USA
February 3, 2009

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I've seen most of the trivalent chrome processes available on the market and they are all clear with not even a trace of yellow. There is a permanganate process that results in a purple-green coating which offers equivalent protection on some alloys, however, I've never seen a yellow that isn't a downgraded clear!

Milt Stevenson, Jr.
Syracuse, New York
February 10, 2009