While searching for something to polish up my brass paintball gun, I stumbled across the perfect compund to repair CD's.
Step 1: What you need!
1 CD that is in desperate need of repair
1 roll of paper towel, and not necessarily the soft stuff
1 roll of reasonable soft and durable toilet paper
1 cloth do place the CD on as to not damage it, and soak up excess Brasso
1 Can of Brasso Metal Polish (MUST BE BRASSO)
Take a look at the intro picture to see what I used.
Brasso is a very unique polishing agent. It is just abrasive enough to remove mild to moderate scratches without being so abrasive that it will scuff the polycarbonate plastic..
One of it's listed uses on the back of the can is for polishing plastic watch crystals.
Step 2: Polishing Part 1
Neatly fold some paper towel up and apply a moderate amount of Brasso. The stuff is runny and has a very strong order so try to not make a mess.
Hold your CD securely and rub the CD with the Brasso covered paper towel in circular motion similar to the way you would wax a car.
You can apply a decent amount of pressure to work out deep scratches but don't crack the CD. The less pressure you use the better the final surface, but you can also go through stages of polishing. Work out the deep scratches then go over with a finishing, light pressure, polish.
I've also used a Dremel and/or a substancial amount of hand polishing to buff out realy deep scratches, but you have to be sure to taper the plastic out gradualy otherwise it will create a reading problem when the laser is directed off at an angle.