Electroplating details for a beginner

Question

I'm looking to electroplate brass rings with gems glued on top of them (though I believe this is then considered electroforming as the copper builds on the glue or epoxy and around the ring and gem?).

What I'd like to know is:

1. What amp and volt size rectifier would be best? Some say 3amp is enough for small scale Jewelry others insist on going up to 25 to 30amp. I can get a 30amp 20volt online for relatively cheap - http://m.aliexpress.com/item/1919812106.html

(They have other smaller rectifiers, all have US plugs but do not state the plug outlet voltage. I live in Australia and need to be sure I can use an adaptor (not a converter) to plug into a 220v outlet).

2. If I use brass rings do I need to paint them first with a copper conductive paint? What if I want to eventually do silver plating? Would brass be okay to silver plate? I know I would need a different bath for that though, I'm just thinking of possibilities for the future.

3. Instead of using a copper conductive paint could I instead make my bath with copper sulphate, sulphuric acid and distiled water mixed together?

4. This is the copper sulphate I am currently using for the bath: http://www.bunnings.com.au/manutec-500g-copper-sulphate-soluble_p2961523 Is this pure enough? For my anode can I use a 99% pure copper sheet to will only 100% suffice?

5. Lastly, do I need to agitate the bath continually? I wouldn't mind a slightly organic look and have read that without agitation this will happen but I do not know to what extent.

I have experimented with copper plating a silver plated ring but the copper did not build up and part of the ring was eaten way at. I used the copper sulphate and boiling water for the bath, a copper pipe for the anode, and hooked the leads up to a 6 volt battery which attached to the anode and my cathode was a copper wire which wrapped around the ring. Not sure where I went wrong if it was the wrong type of copper sulphate, if I need conductive paint, a rectifier instead of a battery or what. Any assistance anyone could provide would be so very greatly appreciated. I've done so much research but am still at a bit of a loss as to what I need to improve upon to make the process work. I'm very keen to start plating my own jewelry.

Answer 1

My first suggestion would be to forget about voltage, current is the important thing. If you can, obtain a current controlled power supply, that way you can finely tune exactly the current that you want, rather than trying to balance the resistance of an electrolyte solution against a fixed voltage supply. A cheap way to emulate this could perhaps be to add a multimeter and variable resistor in series with your plating setup. To do this, you'll need a power supply rated for more current than you need, and a high-ish voltage, perhaps 30-40, or even 50 volts. Then you can watch the current measurement, and tune it with the variable resistor. As for numbers, different settings will give you different results, so I think you should experiment. Perhaps you could make up some test coupons, plate them all at different currents, and decide what you like. Also, the absolute current setting isn't what counts, it's the current per surface area, something else to keep in mind.

You might experience poor adhesion of copper to brass, brass doesn't seem to like to stick very well. A common technique is to first plate with nickel, then plate with copper.

The purity of your components is probably fine, but purer is likely always better.

Agitation is again something that you should experiment with, and decide what you like.

From the sounds of it, I would guess that you accidentally made the ring the anode and the copper pipe the cathode; you must make sure that the positive terminal of your power supply is connected to the anode. It's also possible some kind of coating on the ring may have inhibited the plating in some way, but I wouldn't have expected that to result in corrosion of the ring.

Two things I know nothing about are electroplating non-conductive materials (glue, epoxy, etc) and electroplating of non-metallic materials (conductive paint).