What are effective pretreatments before painting over chrome?
Q. I am the chrome specialist for a large automaker. Do you have any leads on effective pretreatments to chrome and for painting over the chrome? We do use several platers that use pretreatments to chrome before painting. But, in a general sense, do you have any experience with what does and does not work?—J.R.
A. Generally, you need to effectively clean your parts prior to any chrome plating. This may involve the use of an alkaline electrocleaner with a periodic reversed current. This would be followed by thorough rinsing and possibly the use of a dilute acid cleaner with rinsing to neutralize any residual alkaline cleaner. Some shops will first do a copper plating, while others will go directly to the nickel plating. Regardless, either process will require a nickel plating to provide a good base for the chromium as well as good corrosion resistance. I am not sure what processes need to be followed to paint over chrome plating. Generally, you would not spend the money on the chromium plating only to paint over that surface.
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