plating, anodizing, & finishing Q&As since 1989
Color manipulation of chromate anti-corrosion baths
Our current system uses a chromate bath (zinc dichromate on most parts) followed by a powder coat and clear coat to finish our parts. Is it possible to tweak the formulation of the chromate bath to achieve a particular color, thus eliminating the need for the powder coat? The parts are made of zinc.Talbot Presley
director of research - Palestine, Texas
Look into RoHS issues before becoming too vested in this, but traditional hexavalent chromium conversion coatings are dyeable. The colors are pastel rather than saturated and you can see examples in the green grounding screws on electrical junction boxes, and the "metric blue" coloring of screws, bolts, and studs.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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