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What are the spots on unplated ID of plated parts and how to stop them

i am having a problem with my plating process and need some help. but the problem is not with the plating, that is just fine. my problem is with an i.d on the part. it does not get plated. it is going in the tank with a new machine finish and is coming out with black/brownish spots on it. I am sure that is a chromic oxide but do not know where to go from there. any ideas on how to prevent this or how to take off the spot after plating?

Steveo swindall
plating shop employee - Toledo Ohio
November 3, 2009

Hi, Steveo. Is this copper-nickel-chrome plating, or what?

IDs will flash rust because the acid has left them so clean and active. It is customary to include an in-line phophate treatment after chrome plating if you are processing hollow tubing and worried about the ID.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
November 5, 2009

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