Copper plating of propelling pencil threads for use as electrodes: yes, this works.

What’s working so far for me is:

  1. Drop a load of copper sulphate into a jar with some tapwater. It’s a saturated solution.
  2. Take two squares of copper slug tape, and fold then in half twice.
  3. Put each folded square into the croc clip on both polarities of the power supply.
  4. Insert one propelling pencil lead into the folded square if the positive supply. The folded square is there to be a conductive wrap that stops the croc clip from crushing the lead, so it should sit snugly but not too tight. We’re using a lead as the anode so it doesn’t get destroyed in the electroplating process.
  5. Put the other propelling pencil lead into the negative supply, in the same way. This one will end up getting plated.
  6. Suspend the positive pencil lead into the copper sulphate solution.
  7. Turn the power supply on. 3V should do the trick. You don’t want it too high: a high voltage makes the copper come out of solution too fast, and doesn’t make a good surface.
  8. Take the negative pencil lead, and hold it by the insulated part of the negative supply. This is now the cathode. Being careful never to let it touch any part of the anode, shake it back and forth in the solution for about 5 minutes. You do want the cathode and anode within a couple of centimetres of each other. The purpose of the movement is both to clear the surface of the cathode of any buildup of anything that might get in the way, and to make sure the bulk of the solution is getting circulated. You should see the cathode change colour fairly quickly.
  9. Take out the cathode after 5 minutes, and carefully wipe off any liquid. It won’t be shiny: it should be a diffuse, pale pink.
  10. Switch off the power.

The point of this exercise is that now the plated end of the cathode will take solder, so you can attach a copper wire to it securely.

The other end can be sharpened on a piece of paper.