Electroplating
The at-the-time-still-to-become Mrs Flatfrog was, and is, allergic to base metals. She had a ring that she was very fond of that I had given her, but sadly it was a cheapie thing and was starting to bring her out in a rash. I had an inspiration: I'd give her the same ring as an engagement ring, but I'd silver-plate it. How hard can it be? Electroplating something with silver is just a matter of getting a silver solution and a couple of electrodes, isn't it?

A bit of research turned up a photography suppliers that could sell me some silver nitrate, but then I was stuck on the electrodes: I realised that the anode (or cathode, I can never remember which is which) had to be carbon, so that it wouldn't dissolve. No problem - a pencil lead is basically carbon. I got a thick pencil and took the wood off, then attached it to a clip. On the other side, I hung the ring from a wire to make my cathode (or anode) and hooked up a 9V battery, then I dipped the electrodes in the solution. Satisfying bubbling ensued, at the end of which the ring was coated in a layer of nasty black gunk which proved impossible to remove.

The story ends well, as I took the measurement of the ring to get something that was actually silver to propose with.
( flatfrog Staring vacantly into space, Thu 24 Jul 2008, 15:31, 2 replies)

*clicks*
Something my mate told me that helped me pass Chemistry A-level:

"Cations are pussytive"

(Therefore anions are negative, as are cathodes. Anodes are positive.)

Silver ions are positive, so you wanted the ring to be the cathode.
(tarbin tarbis, tarbit, tarbamus, tarbimus, tarbant, Thu 24 Jul 2008, 15:50, closed)

Tarbin is correct
but electroplating isn't actually that simple in practice. Believe me, I do it at work.

You need lots of additives to control how the metal deposits, and also a current-regulated power supply to do it properly. It's also better if you use larger area samples. A ring is a bit small.

Incidentally, I have successfully copper plated 'silver' coins, and nickel plated copper ones. I think I'll go and write an entry on that!
( K2k6 has a proper job these days, Thu 24 Jul 2008, 16:15, closed)