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  for Metal Finishing since 1989
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New Chrome on Old Chrome

have you guys ever done plating of a new chrome layer on old in-service chrome? I am thinking about locally blending some areas of in-service chrome and plating it again. I have seen some reporting excellent adhesion without any problems. Any suggestions?

A. Durmeyer
Shop - GA
2007

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May we assume this is a hard (engineering) chrome application, A.? If it shafting?

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

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Ted,
Thank you. Yes Hard Chrome. I have hard stories of putting a new layer of chrome on in-service chrome. just wondering what you guys think.

A. Durmeyer
plating shop - Atlanta, Georgia
2007

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2007

I have seen lists of which etching solution to use for which substrate, and I am pretty sure I have seen chrome on that list as a substrate, so it sounds possible. If you have Guffie's book available I'll bet it has the answer.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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2007

Hello Everyone,
The Air Force has been laminating new chrome over "old" chrome for years on landing gear components. 5 years ago I performed lamination tests with condemned components that had been in service for years. We performed adhesion and grinding tests in addition to cross sectional analysis. Even under a microscope it was difficult to discern between different layers of chrome plate. This is engineering hard chrome with thicknesses of 8 to 15 thousandths. Solvent clean the old chrome, 1 minute reverse at 2 asi in the chrome plating tank, then ramp current from zero up to plating rate linearly over 5 minutes.
Thank you,

Nathan Hughes
- Hill AFB, Utah, USA

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Can it be done? Yes, by many platers, but certainly not all of them.
Next, you have to look at - Is it allowable? There are a number of parts that it is not allowed on in jet engines and other "high risk" areas. I am a bit surprised that the AF allowed it on landing gear and also by the unusually thick layer. Chrome is normally highly stressed and the thicker it is, the more the problem can be.

James Watts
- Navarre, Florida
2007

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I have had a lot of luck with putting a new layer of chrome on top of a old layer of chrome. Now there may be some argument to the method that I use to do this. I am etching in the same tank that I am going to Plate in. The Method that I have found to be the best is using 2 amps/sq. inch for the plating process. And for the etching process I would divide the amps required to plate by 1.5

The piece goes into the tank and allowed to warm up to temp. It is then reversed etched for 1 minute and 30 seconds. After this quickly change the polarity to plate and ramp the amps up to what you need to plate for 30 seconds. After the 30 seconds drop the amps to 1/8th of what is needed and slowly bring the amps up to the desired level as if you where plating anything else. The adhesion of the chrome on top of the old chrome is excellent. I have had no problems with this process. It is hard to tell that the piece was even plated with new on top of old.

Jim Moore
- Pennsylvania
2007