I’ve seen a lot of people clean CDs completely wrong. There’s a good reason why most libraries and video rental stores have labels on their discs telling people not to try to clean them—if you do it wrong, you have a good chance of permanently damaging the disc.
There are a lot of ways to clean a CD, but first, here’s how not to clean a CD: Do not rub around the CD in circles. This can cause further scratches. (Furthermore, circular scratches are the most likely to cause permanent data loss, as they wipe out a large amount of consecutive data. Most systems have an error-correction algorithm that can compensate for a small amount of consecutive unreadable data, such as when the disc scratches from the center to the edge.)
Here are two acceptable ways:
- The simplest way is to take a soft cloth and some CD cleaning solution (lens cleaner is almost the same stuff, and is often advertised as both), spray a bit of solution onto the cloth (I’ve heard that you’re not supposed to spray it on the disc, although I’m not sure why), and rub the CD gently from the center to the outside of the disc. Then turn the disc slightly and repeat. As mentioned above, don’t use any other pattern.
- Another common method is to run it under the tap and then wipe it off gently (from center to edge, of course), or let it air dry. Some people recommend taking it into the shower, which does essentially the same thing.
If a disc is badly scratched, many people report getting good results by rubbing toothpaste all over the disc, letting it sit for a few minutes, and then cleaning it off. The idea is that you wear off a thin layer of the non-scratched portion of the surface, thus making the scratch shallower. This is not something to try unless the disc doesn’t work anyway and you realize that you might destroy it completely.