[Chrislong]

Nitromors paint stripper.

its evil stuff, don't get it on anything - it'll burn skin, and the fumes hurt eyes. It'll literally melt anything but the metal.

If you hang your springs on string and dangle them in, you should be able to make it melt all but the colour on the first coil.

Or you can cut 5mm of coloured tubing (off wire) and wind it up the coil. I do this on cut springs so not to confuse them with uncut (I have done it)