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Ted Mooney, P.E. RET
The authoritative public forum
for Metal Finishing 1989-2025
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Dummy Plating of Chemical Conversion Coating Bath
Quickstart (no readers left behind):
The process solutions used for metal finishing can become contaminated from various sources such as drag-in from previous tanks, parts dissolving in them, and so on.
One purification method which is sometimes applicable is "dummy plating", i.e., plating onto scrap at a low voltage/amperage that is sufficient to plate out the contaminant without plating out a significant amount of the solution. The most common use of "dummy plating" is for removing copper from nickel plating solutions.
Q. Can you dummy plate Chemeon TCP-HF without removing the Chromium?
Jessica BoikeChemical Engineer - Madison, Alabama
April 25, 2025
This product is a trivalent chromium conversion coating for aluminum. Conversion coating imparts a stand-alone corrosion resistant finish but can also be used as a base for paint or powder coating. Conversion coating was historically done with hexavalent (toxic) chrome; this process uses trivalent, chromium, considered far less toxic.
A. Hi Jessica,
Wow, dummy plating of non-electrolytic processes is a possibility which never occurred to me.
I'm pretty confident that dummy plating will not plate the chrome out of a chromate conversion coating bath, but what will actually happen to the tramp materials like zinc or iron in it is a great question.
I would suggest, however, being very alert to the possibility of creating hexavalent chromium by doing this.
Hopefully, someone in this wide world tried it and can offer some input 🙂
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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