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What Metals Will Hard Chrome Not Deposit Onto
August 26, 2015
Q. Hello, I have been looking around and have not been able to find a list of metals that Hard Chrome will not buildup on. This is my question: What metals can be put into a Hard Chrome bath that will not get chrome deposited on them?
Thanks for your time!
- Portland, Oregon, U.S.A.
Hi Kelson. Casting a question in the abstract, instead of telling us your actual situation and what you're trying to do, can turn an interesting & answerable question into a dull one which will likely garner misleading "answers" :-)
Are you interested in the situation where the metal is simply placed in the solution, electrically neutral ... or the situation where it is part of the plating rack, or part of the article being plated, and is thereby cathodically charged? Chrome ions will be reduced to chrome metal on any material which has a sufficient excess of electrons on it. That probably includes all true metallic surfaces in high current density areas, but may exclude some metallic surfaces which have a sufficient oxide coating to serve as an insulator and/or surfaces which are far enough from the anodes such that hydrogen evolution will result instead. The chrome will not properly adhere to surfaces that are not clean and active, but there's a difference between not adhering properly and "not get chrome deposited". It's not okay to put most metals into the chrome plating solution anyway. Guffie's "Hard Chromium Plating" has an 8-page chapter on fixtures where he makes that point a couple of times. Best of luck.
Ted Mooney, P.E. RET
Aloha -- an idea worth spreading
finishing.com - Pine Beach, New Jersey