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Checking for plating coverage
December 5, 2012
Q. We currently have parts that have been zinc yellow chromate plated and the appearance is inconsistent. How do we verify that the plating is there and it is just an appearance issue?
As an example, we have nickel plated parts and if an area looks "funny" we place a few drops of copper sulfate on it, if it turns red then there isn't any plating present.
Is there a similar test we can do?
I suggested placing the part out side in the environment an see if rusts with in a week or so, we are in up state NY so there isn't any salt yet (snow has not hit us yet).
Any help would be appreciated.
- Rochester, New York, USA
A. Copper sulfate will work there too if the substrate is steel. Chromates look a little inconsistent once in a while. An ASTM B117 [affil. link to spec at Techstreet] neutral salt spray test will tell you everything you need to know, but they cost some bucks.

Trent Kaufman
electroplater - Galva, Illinois
