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Alkaline Zinc plating bath with 50% caustic

Hello. I run a electroplating zinc bath with caustic soda [affil links] 50%. How will the caustic react with the zinc if the zinc metal concentration is low?

Tedd Tubbs
waste water - Clinton, Iowa, USA
April 21, 2011

Hi, Tedd.

I'm sure your question is clear in your mind; sorry, but it's not clear in mine. It sounds improbable that you are running at a caustic concentration of 500 g/l, as this is about 3x the conventional, so I may be misunderstanding. But the caustic dissolves available zinc anodes and, usually you will be battling over-concentration rather than under-concentration. Letter 32782 goes into a bit of depth about zinc concentration in alkaline zinc plating baths.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
April 23, 2011

If you are operating at 500 gpl surely you will decrease the bath efficiency to the least. Above 160 gpl the efficiency decreases and you may be passing current only to heat the bath. What is the basic reason behind this new idea.

S.V. Aurobind
plating process supplier - Bangalore, India
May 17, 2011

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