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-----Blue Color Powder on Silver Plated Parts
Q. We are observing "blueish color" buildup on silver plated surface with under plated nickel (silver plate over nickel underplate) on copper-based substrates. We have seen tarnish with yellow or brown colors but never seen a "bluish discoloration or layer build up. The silver-plating line is based on silver cyanide. The plating process includes pre cleaning, acid etching, nickel strike, nickel underplate, and finally silver plate. We will have a hot DI rinse with an anti-tarnish chemical to prevent immediate tarnish, while we assemble parts to it and ship to Customer.
I would request some help and guidance on this issue.
1) Is the bluish color or layer we found on the silver-plated surface is "Tarnish".
2) If Tarnish, why this is showing "blueish color" other than black or brown
3) Is the bluish color on the surface is due to improper or insufficient rinse?
4) Does the cyanide-based silver plating can cause bluish color on silver plated surface.
Quality Manager - Chicago, Illinois
April 22, 2025
A. It looks like copper sulfate (or maybe copper nitrate) to me. That vivid blue color is pretty distinctive. Corrosion products of nickel tend to be more greenish as you have said.
Jon Barrows, MSF, EHSSC
Independence MO
A. Hello Elias, Sorry to take a while to get back to you. The problem you had may have been solved. But if not, have you determined whether the bluish hue is from the silver plate or after anti tarnish? You could do a test run with 2 groups, before anti tarnish and after. Keep the test run in a clean environment, such as an office. When was the last time the silver bath was analyzed for metallic contamination? Iron, nickel, copper and zinc are the common contaminate metals.
Mark BakerHappily retired - Cazenovia, New York
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