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DUMMY PLATING FOR COPPER BATH
I want to know if dummy plating can be applied to a copper bath to reduce chloride levels and which are the conditions for this application.
GERMAN QUINTERO- CALI, VALLE, COLOMBIA
2003
I don't think so. I might be missing something, but dummy plating is used to plate out undesirable cations, but does not effect anions like chlorides.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003
I am not sure, but when we have been forced to use insoluble anodes, for instance graphite, in our Woods strike, gaseous chlorine evolves on the anode. So it might be possible under certain conditions to produce the desired effect in a copper bath. On the other hand, other anions such as sulphates, cyanides or fluoborates might also be oxidized under those conditions and produce undesirable results. You may want to try with different anode-cathode ratios, temperatures and current densities in small volumes of bath and see what happens before attempting to treat the whole solution. Finally, get back with the outcome so we can all learn.
Guillermo MarrufoMonterrey, NL, Mexico
2003
The applied voltage to plate out copper is frequently as low as the chlorine overvoltage potential, so it will be very difficult to get a significant amount chlorine outgassing by dummying. Translated, I do not think that it is a cost effective way to reduce the chloride level.
James Watts- Navarre, Florida
2003
You can reduce chlorides in a decorative chromium bath by using very small cross-section cathodes with enough current that they almost melt off, or at least glow, above the solution. It doesn't take much amperage with such a small surface area.
Chromium is much more electrically resistive than copper. The copper may reduce the resistance of the cathode too much, too soon. Unless the copper plates too readily it is worth a try. Pick a rod of a material from which you can strip the copper. If you put enough energy into graphite it may sever at the liquid surface.
Paul Morkovsky
- Shiner, Texas, USA
2003
May 2, 2012
Q. We are a job shop that copper plates gravure rolls for engraving.
We plate a wide range of sizes. Over time our copper sulphate [on
eBay or
Amazon]level rises
and we have to pull solution and dilute with water to lower sulphate levels,
this in turn lowers all the levels of my bath.
Is there a way to Dummy Plate to plate out the high levels of Copper Sulphate?
I try to keep the anode to cathode ratio as close to 2-1 as possible but the Sulphate level always rises.
any suggestions would be appreciated
- Cincinnati, Ohio, USA
A. Hello Eric,
We have the same problem from time to time. We pull our Cu anodes, install 4 carbon anodes, and use Cu sheet material as a cathode. If you have multiple cells or multiple anode and cathode bars you don't need to replace all your Cu anodes with carbon. We usually take the cell at the center of the tank. The solution transfer (air, eductors, or solution agitation will be enough to replace fresh ions at the cathode. Cu isn't cheap anymore and you can use the sheet over and over again with the proper pre-clean cycle of course. Some platers use stainless steel as cathodes then peel the Cu off after each dummy plating. You can contact an anode supplier for the carbon anodes. As far as the Cu sheet material, I forget where I got them, as it has been so long ago. You will have to do Cu concentration analysis before and after to determine the current density and time. What has also helped us is we turn the air agitation off (if applicable to you) when the bath will be idle for an hour or more. Hope this helps!
Engineering - Mesa, Arizona, USA
May 8, 2012
A. Hi Eric,
Since your cylinder sizes can differ (I expect a wide variety of cylinder face length and circumferences) then it is very difficult to maintain your right anode cathode ratio. Therefore it is recommended to install a little tank behind your tank, a little bypass in your filtration system into a smaller tank (Volume <200 ltr and equipped with filter for activated cartridges). this tank should be equipped with an appropriate cathode material and a lead anode and connected to a rectifier with a max of 200 amps. Then you plate out your copper and gain a very pure copper which is easy to sell and lowering your anode costs up to 75% (right choice of metal recycler). The other advantage is, that you always can run "preventive maintenance" on the electrolyte by running the electrolyte over a activated carbon filter cartridge in order to absorb organic contamination which may is dragged in from the previous degreasing process and/or ink residues from the gravure printing process.
Cheers,
Dom
- Melbourne, VIC
May 11, 2012
! Thank you for your input regarding lowering copper sulphate
levels in copper plating bath. I will be getting with my operator to discuss what approach will work best for us.
I will post an update once we implement changes.
Thanks again.
Eric
- Cinti, Ohio, USA
May 21, 2012
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