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Satin nickel and black stains

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Hello... We plate zinc die cast with cyanide coper then acid copper then satin nickel. But with both zinc die cast parts and mild steel parts after the satin nickel they are getting blackened like black stains. We polish them but it was in vain. Our scrap rate is getting high. Is it possible excessive satin brightner? or...? So... Could you help me?

Emre Tuna
engineer - Istanbul, Besiktas, Turkey

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Hello,

I think for zinc dicast components u need to give a very good coating of cyanide copper , which is been deposited at lower current and a very smooth deposit, also then a bright nickel coating and at last satin nickel, if the satiniser is not been added at controlled measure it results in black spots , also if the primary additives are not in range also ends up in such problems , carbon treat the bath, dummy , make rthis a regular practise and work with limited additions of satiner , ALL THE BEST !

REGARDS

Praveen Kumar     plating process supplier Mumbai, India

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First of two simultaneous responses -- ++++

Raise the Nickel sulfate content above 400 g/l. I know it sounds strange but it is a proven method to solve black spots problem on satin nickel.

Sara Michaeli     chemical process supplier Israel

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Second of two simultaneous responses -- ++++

Hi, get long-time stable satinizer. Satinizer breakdown will bring this guest (so called black spots) to your house regularly.

Good luck

Qutub Saify
- Ajman , United Arab Emirates