Using Hull Cells for Silver Plating
Hi Plating Expert,
I need some clarification on how to set the Hull Cell specifically for the Silver Plating Finished, then how about the basic calculation involved and how does the hull cell explain the actual bath / brightener performance.
Thanks in advance...sam
- Penang, Malaysia.
Hello, Mr. Sam (please provide your full name on any follow-up):
The Hull cell is nothing but a miniature plating tank where a test panel is used as the cathode and is placed at a diagonal to the anodes so that it experiences very high current density at one end and very low current density at the other.
The Hull cell doesn't ring bells or flash lights to tell you what to do, all it does is let you see what the plating looks like on a properly prepared substrate. The current density at the high current density end should be greater than the highest current density in your real plating tank and the current density at the low current density end should be less than the lowest current density in your real plating tank so that you can see problems coming as they manifest themselves at one current extremity or the other.
From experience, you guess at what ingredients you need to add to get better plating in the Hull cell, and after proving that it worked, you simply scale up and add those ingredients to your plating tank in the same ratio.
AESF (www.nasf.org) has a very nice Illustrated Lecture on Hull Cell Testing, and references like The Canning Handbook will help you with the guesses about what to try based on your initial Hull cell result.
Ted Mooney, P.E.
Pine Beach, New Jersey
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