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Ask the Expert Question-and-Answer Archive
(Hard Chrome Plating)

by Larry Zitko, ChromeTech, Inc.
December, 2002

Triple Chrome Plating

Q. I heard someone use the term "triple chrome plated". They explained that the steel part is dipped three separate times in a solution before being polished. They claim that the chrome comes out thicker. Is this possible?

A. Due to the low efficiency, slow plating speed and tendency for chromium to produce rough deposits with heavy buildups, platers will often plate a part requiring a thick chromium coating over more than one plating cycle. It is fairly common to grind or polish the chrome after the first layer, then plate "chrome-on-chrome" as needed to get the desired dimensions. A special activation technique is needed to accomplish a satisfactory bond between the two chromium layers.

The polishing step after the first layer will result in smoother subsequent deposits. It can also improve the corrosion resistance of the final product significantly, because it creates a smeared boundary between the microcracks in the first and second layers of chromium. Generally, there is no need to polish between any subsequent layers.

Most parts are plated with chromium using a single plating cycle. This may not be possible if the required chromium thickness is too great, or if the plater cannot accurately estimate the plating rate of deposition and plating time. Platers will often pull a part from the chrome tank, measure it quickly, then immediately return it to the tank and resume plating if it needs more thickness. This process may be performed more than once. If the part is not polished in between, the part may have a rougher deposit, even it receives the desired final thickness of chromium. Also, this procedure may result in a weak bond with the potential for peeled chrome.



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