Hi all, I'd eventually like to form a trumpet receiver and bell out of pure copper, and the standard method to do that, from what I know, is electrodeposition. This is done using a mandrel made of iron or something else with a lower reduction potential than copper's. I've calculated (initially ad-hoc, and just now using Faraday's law of electrolysis) that it would take 383 amp-hours per pound of copper, and the bell will likely be around a pound in weight, so this could take a good number of days. I haven't done any advanced electrochemistry yet so I only now discovered how Faraday's law can be used. I rearranged it (see the attached png) and used Faraday's constant [url=http://www48.wolframalpha.com/input/?i=Faraday%27s+constant+in+amp-hours+per+mole[/URL] instead. The minimum voltage for electrolysis is the potential difference between the reduction potentials of the plating material (in this case, +0.34 volts) and the mandrel (for iron, −0.041 volts). More significantly, there's also a vague upper limit – when the electricity plates copper on the cathode faster than the acid dissolves it from the anode, the following happens, somehow producing smut on the surface of the cathode: [b]2e⁻ + 2H₂O → H₂ + 2OH⁻[/b] (E° is −0.83 volts) The question is, how do I find the maximum voltage that I can pump through, without producing smut? This depends on the concentration of aqueous copper, which I don't know how to change. Why doesn't more voltage speed up oxidation in addition to speeding up reduction? Does current aid oxidation at all, or is acidity the only factor in dissolving the copper? If that's the case, what's the relationship between the acid's pH/pKₐ and the dissolution of the metal? All the electrolysis examples on the net are lab demos for kids, so they use vinegar, which has a relatively tame pH of 2.4. I'd rather use diluted nitric acid in order to increase the molarity of Cu²⁺ and hence the maximum rate of electrolysis. Thanks in advance for any help with this. I'm a little stumped. :) [b]Edit:[/b] Looks like copper reacts with some of the nitrate in nitric acid, and this is a redox reaction in itself – no reduction potential. Maybe that's why current is irrelevant in oxidizing the copper. It also means I would need a substantial supply of nitric acid.