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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing since 1989
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Tin plating over nickel plating on brass oxidized to black problem over tin plating
April 12, 2010
Hello
My question is we did Electro Tin Plating with under quote of nickel over our brass components and after some days it became black.
Can you please suggest us how to prevent this.
Thank n Regards
Manufacturer - India
April 14, 2010
Dear Nilesh,
Several possibilities: A very bad Nickel plating, porous and/or Cu-contaminated and a thin Sn-layer leading to discolouration in a few days (unlikely).
Contaminated Sn electrolyte (too much organics, too much Cu (also unlikely as mostly already visible after plating).
Bad rinsing. Make sure that the parts are thoroughly rinsed (cold / hot / cold water rinse with pure water) and then dip the parts for some time (seconds to a minute) into a 25 g/l. Potassium carbonate solution and rinse again thoroughly.
As volunteers, we always like to get feedback about what helped you out, hope you won't forget that afterwards.....
Success,
Harry van der Zanden
consultant - Tilburg, Netherlands
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