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Q&As since 1989


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Hexavalent free chromate and silver free black chromate

(2002)

We are a zinc electroplating job shop having excellent expensive success applying hex free chromate on top of zinc and alloys but only to clear/iridescent color!

My question is "Does anyone have a hex free, silver free black chromate to apply to zinc and/or zinc alloys?"

Cliff Roy
plating shop - Conestee, South Carolina

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Cliff,

I too am in need of black tri-chromate for zinc-nickel alloy.

Over the past several months, I have talked to many major chemical suppliers. The general feeling that I get is that replacement hex free chromates are first be available for the most popular chromate conversion coatings first such as zinc yellow for example. Since black conversion coating, especially for zinc-nickel, are not as common, they will be last one developed, tested, and marketed. So far in my search, I had no luck yet.

Karl Weyermann

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There are a few plating chemical suppliers working on it, but I have not yet heard of one of these systems making it from the experimental stages to being ready for production use.

When it comes out, I expect it will be for use on zinc-iron or zinc-iron-cobalt platings. This type of zinc alloy is easiest to get a good black on. Black is probably the hardest color to create from a technical standpoint.

Tim Neveau
Rochester Hills, Michigan

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The manufacturer of Chromiting, Surtec GMBH has a black version of Chromiting for use on zinc and zinc alloy surfaces. This is purported to be non silver, trivalent.

Gene Packman
 

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2005

Do the Vendors have "Hexavalent Free Silver Free Black Chromate" for Zinc Plating yet?

Mathew Schaefer