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Making Dummy Cathodes for a nickel sulfamate bath

I have searched for a place to purchase some corrogated dummy plates for our nickel sulfamate bath and was unable to locate anyone. Is it possible for someone to provide some guidance pertaining to the dummy plate perameters, i.e. material to use, size of plate versus tank size, most of our tanks are 350 gallons, and dimensions for the folds in the metal, this is of course if we have to fabricate on in-house? I thank you in advance.

Jack Honore III
hologram industry - Robbinsville, New Jersey
July 16, 2008

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July 17, 2008

There used to be a few places that sold the dummy cathodes.
I used corrugated steel that I stripped the zinc off and used. The problem that it had was it was a one use material as the cathode rusted heavily at the plate-no plate interface.
I took some 0.030 316 SS sheet to a sheet metal shop and had them bend 90 degree bends (sharp) in it. It gives you a very very low density area that you can use as a guide for the amperage that you use. Typical is about 2 amps per square foot. You can use a bit higher, but you waste more nickel. If you are in a rush, use 5 ASF for the first try.
Strip the cathode. You may be able to actually peel the trash plate off if you do not clean or activate the cathode. Put it away dry and periodically use it over night to keep the trash metals to a low level.

James Watts
- Navarre, Florida

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Hi Jack,
Usually dummy cathode plates have as large an area as possible. So, make them a little shorter than the cathode rail and about the depth of the anodes. Corrugated as already explained. Before you start dummying, plate the sheets at a higher current density to get a good sound nickel layer. It is very important to have good agitation during dummying to ensure that the contaminants are brought to dummy sheet. Otherwise you will get a nice clean sheet and keep the contaminants. A classic problem is wanting to dummy overnight but not wanting to run the air compressor for safety/noise reasons.
Harry

Harry Parkes
- Birmingham, UK
July 19, 2008