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Bubbles in zinc plate

Greetings, my vendor has sent me photos of a zinc-plated part that exhibits extreme bubbling...sorry but I cannot remember how to post a photo on this site....it looks like thousands of tiny bubbles in the surface of the material. The parts are heat treated steel which are then plated with clear zinc.

Any ideas on what could be causing this and what steps to take? Thanks!

Scott Dupre

2006

Ed. note: To include a picture, just e-mail it to mooney@finishing.com. We figure out what letter to post it on from your e-mail address.

Improper cleaning or activation. This includes excessive as well as under.

James Watts
Navarre, Florida
2006

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It sound like a hydrogen problem in the steel and is showing later.
If running cyanide zinc, try stripping the articles and leaving them in your hot soak cleaner over night. In the morning rinse well in clean water and put them straight into the plating tanks, no steps in between.

Gary Joseph
Johannesburg,
South Africa
2006

I think its due to hydrogen embrittlement. What type of plating you are doing, its acid zinc or cyanide zinc. If you are using acid zinc , try to reduce the HCl concentration as well as use the inhibitors in correct ratio. Use less time HCL. In Zinc plating run with less voltage. check the contact points regularly. If you are running high voltage it will cause HE. If you are doing cyanide plating.its efficiency is less. it will cause HE

Sankar

2006