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Alkaline vs acid zinc
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Which is better....alkaline or acid zinc? Alot of the responses are 3-5 years old and I am wondering if tecnology 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
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.
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 Ted Mooney, P.E. finishing.com Brick, New Jersey |
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
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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.
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Robert H Probert Robert H Probert Technical Services  Garner, North Carolina
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