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Alkaline vs acid zinc

Which is better....alkaline or acid zinc? A lot of the responses are 3-5 years old and I am wondering if technology has changed. The parts average 8 square feet requiring throw into low current density areas. Brightness is important but not crucial.

John Skuchas
- Upland, California, USA
2003

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First of two simultaneous responses --

Yes, alkaline zinc offers better throw. As a very broad and general rule of thumb, yes, alkaline zinc has improved to the point where it is usually the first choice for rack plated parts.

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

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Second of two simultaneous responses --

Alkaline non-cyanide zinc plating is generally better than acid zincs where a good throw into low current density areas is required. Modern formulations can give a brightness which although not equal to, is fast approaching that of acid zinc. Distribution from alkaline non-cyanide solutions is also far superior to that which could be expected from acid zincs.

Dougie Lightfoot
- Fife, Scotland
2003
2003

Alkaline will throw better, Acid is slightly brighter.

Once I had a client who needed both, so we alkaline plated first to throw into the deepest recesses, then we topped off with a bright acid zinc. We used a HCl dip in between. Since the acid zinc "saw" only pure zinc, it did not build up in iron like a conventional application would have done.

Your zinc vender would love this advice, but just try the alkaline by itself first.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2003