Summary for gold plating unknown substrate Discussion
gold plating an unknown substrate is discussed as a finish-quality problem rather than a gold-process problem. Daniel Hunter says his decorative metal pipes from China looked like chrome or stainless, but brush plating produced patchy, dull, uneven results; reversing current to strip the surface made it murky, and a nickel strike only helped one part while the others stayed dull or unchanged. He asks what to try to identify the base metal and improve the result. Mark Baker replies that the final appearance will mirror the substrate, which he believes is zinc, and warns that a nickel strike cannot create brightness the way a bright nickel plate can. Because brush-plated gold is only a very light coating, it will reflect the underplate. His practical advice is to start with a clean, bright surface, use a good soak cleaner, and polish the parts first if possible.
March 30, 2016
Q. Dirty, dull and un-even looking paint. I have some decorative metal pipes from China. I wanted to brush plate them in gold. They looked like they were already plated in replica chrome or stainless steel but upon first attempt to plate, it did plate but patchy and dull and uneven. So it’s not either. They were de greased and activated.
So I then tried to see if I could strip the current plate by reversing the current. This left the plate very murky and nasty. So I was told that these tubes were zinc plated. So I got a nickel strike. Now, strangely, one came out satisfactory but still dull. One plated pretty much similar to before, and one it did nothing to. These all looked the same starting, shiny chrome.
I’m using a brush plate with a dc/ac
Using ss at 12v for the degreaser
Using ss 12v reversed for the stripper
Using nickel 4v with the strike
Using ss 9v for the gold plate.
Does anybody have any ideas of things I could try to work out what is going on? Thanks.
Daniel Hunter
– Uk
A. Hello Daniel, keep in mind that whatever the substrate (zinc) looks like, is what your final finish will look like. A nickel strike cannot build brightness like a bright Ni plate. In brush plating, gold is only a very light coating so it is also reflective on the underplate or substrate metal. Can the parts be polished before any plating? If so you will need a good soak cleaner. If you start out with a clean, bright substrate, you have a lot better chance achieving a good looking plate.
Mark Baker
Process Engineering – Phoenix, Arizona USA
April 8, 2016