Rit dye works wonderfully. I use a color called pearl gray. Follow the instructions, heat it up to a aboil and let it cool to the touch. Stip off your line and let it sit int he dye for a several minutes. Wipe it clean, and you're ready to go. Store your dye for later use - just simply heat it back up and use it again.

I've done it for well over five years and have never had an issue with the line after I applied the dye.

D.A.