I am planning to try electroplating a steel ring with copper, than nickel, and than finally gold. It seems to me that this would be as simple as using a bath of HCl for electrolytes and attaching the object to be plated to the cathode and the metal to be plated to the anode. I though I would then simply run a current through the setup. However, I have seen several "recipes" for electroplating using other electrolytes such as copper and nickel sulfate or dissolving the gold in aqua regia or cyanide before the plating. Is this necessary, as the metal to be plated will dissolve into solution when electricity is run through the circuit anyway. I would prefer to buy fewer chemicals if possible and reduce the complexity of the process, while obtaining the best results.
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asked May 26, 2016 at 0:36
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1 Answer
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There are two issues here:
First, you will be oxidizing water. You would end up making oxygen in most of those cases, before oxidizing your metal and making the cation you need.
Second, even in cases where your metal will oxidize before water, the concentration of the metal cation in the solution will be low and variable. This will create problems with controlling rates of deposition and uniformity of deposition.
That is why the electroplating baths rely on the already dissolved cation and not the metal as the source. This way you have lots of the cation you need in the solution to work with and you can put some inert counter electrode.
