Oxidising copper jewellery (or Adventures in Egg Land, part two)

I have already tried oxidising silver jewellery last year, so when I read that it's also possible to use the same method to oxidise copper jewellery, I decided to give that a go. I recently ordered some copper findings from a fantastic seller called RoyalMetals and my goodies arrived this week. I set to work making some earrings with them, and then picked a pair which I thought might suit the darker brown colour of oxidised copper:

When I tried oxidizing the silver earrings last year, I used a tupperware container. I've seen tutorials mentioning ziplock bags, so I thought I'd try that this time. I read online that copper-plated items might not oxidise well, so I 'cleaned' the metal bits of the earrings with 70% alcohol (from the first aid box, not the drinks cabinet). Acetone is recommended for this, but I didn't have any, as I buy acetone-free nail varnish remover (to go with the numerous bottles of nail varnish I own but never use).

So I hard-boiled a couple of eggs, and put them into the bag. I then bashed merry heck out of the eggs with my hand. It was a bit warm, but great for stress relief. Actually, this would probably work even better if you draw a face of someone you don't like on the eggs first. *makes a note for next time*

 Note: If you are trying to lose weight, you can open the bag at this point, and take a good deep breath of the eggy fumes. I bet you won't feel like eating much after that. Nice. :-)

Then I added the earrings to the bag:

"Hey, a sauna, this is kind of relaxing. Wait, what's that awful smell? No, I've changed my mind, let me out. I'm choking..."

So I left the earrings in the bag, and tried not to keep looking at them. Occasionally I would poke the eggs a bit to release more of the fumes. After an hour or two, I could see a colour change, but it wasn't quite dark enough. So I left the earrings in the bag overnight, and this is how they turned out:

The earring wires have worked really well, but the headpin wire and bead caps are a bit patchier. 

That could be because I didn't clean them with the alcohol properly. I guess I could try oxidising the individual components first then making them into jewellery. Or I could just buy them ready oxidised. But where's the fun in that? :D