This is simple quick fix for old CD's / DVD's using a hot air soldering station (in my case Dremel Versatip).
I guess this would work with any kind of directed flame or even a ordinarylighter, but it would be time consuming.
There are a few tips you should follow:
1. Be patient and work slowly. It's best to let the CD cool down from time to time.
2. Don't concentrate on a single spot for too long, or the CD will end up being deformed.
3. Graduallyreducethe distancebetween thesoldering tip and the CD until the scratch disappears.