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Staining in brass plating

We are plating brass on plastic parts, but in this moment brass is staining after one day.

The cycle is:
after bright nickel electroplating:
rinse
brass plating-one minute
rinse
rinse
Electrolac (I think is a electrolytic chromate)
rinse
rinse
Electrodip (immersion chromate)
rinse
rinse
This process has been used for many time and the problem appear one month ago. Let me to know your recommendations and if some product similar to Electrolac.

Carlos Godoy
PEMSA - MÈxico, D.F.

Most brass plating is cyanide based, and I assume yours is. Cyanide plating solutions are very prone to 'bleed out', and they require excellent rinsing to prevent it. Is it possible that the problem is really back in the rinses after plating, rather than further into the process?

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Ted is available for instant help
or longer-term assistance.

Mr Mooney is right about the rinsing. You need three DM water rinses pH aroud 6.0 to 6.5 after Nickel and again after brass. After brass you need a 2 % H2 SO4 rinse before the lacquers/ anti-tarnish.

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

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