What are the major metals used for plating?
I am a high school chemistry teacher with an informational question. Could you tell me the top three (or five) metals used for plating, and perhaps the approximate amount of each used in the U.S. (and/or worldwide) each year?Karen Howard
A. Purely guessing, I vote for in descending order by weight:
1. Zinc, 2. Nickel, 3. Copper, 4. Tin, 5. Lead.
Hope I didn't flunk the test...
December 5, 2012
A. Hi Karen. I'm very confident that Dave has #1 and #2 dead on (I'll come back to that).
I'm inclined to believe his #3 and #4, but my speculation for #5 would be silver. This is not based on any real analysis of mining or commerce data, but merely a career spent visiting and working in a thousand plating shops; an acquired feel for how many plating tanks, of how much volume, I've seen for each; and ongoing trends (years ago there was a lot of cadmium plating done, but that has greatly declined, although it's vaguely possible that it's still in the top 5).
It's not as easy to find these numbers as you might think. Let me relate an old story about #1 and #2. In the earliest days of the EPA, they commissioned a report on the plating industry designed to come up with an overall regulatory strategy. The study cost millions, the assignment was given to one of America's best known research institutions, and since reputation sometimes passes for authority, they began with the assertion that Nickel was the most used metal in plating (perhaps they made this assumption because most of their prior government assignments concerned nickel plating). The first challenge the report faced was the complaint that the people preparing it were clueless about the industry they were supposed to be preparing a strategy for, because a quick back-of-the-envelope analysis showed there to be about 10x as much zinc plated as nickel.
I can say with 100% confidence that the 5 metals I mentioned are very widely plated. But exact numbers are very hard to find for a hundred different reasons like these: I know at least one shop that does a large volume of copper plating but never buys either copper plating solution or copper anodes... they buy and dissolve copper scrap. Some amateur platers buy and use "root killer" as their copper supply. Some shops etch copper in sulfuric acid and peroxide, then apparently use the copper sulphate which this generates as an additive in their copper plating tanks. A certain percentage of purchased plating supplies are "thrown out" due to contamination, without ever being used, etc.
You could talk to nasf.org and ask about their Surface Finishing Market Research Board reports, but as I imply, every data source has real limitations, and must be viewed as a very rough approximation at best. Good luck.
Ted Mooney, P.E.
Pine Beach, New Jersey
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