Optical discs have been common for more than 30 years now, and scratched discs have been common for just as long. Just about everyone has experienced a CD that skips or a DVD that freezes. Optical discs are read by lasers, and a little scratch or splotch of grease is all it takes to interrupt the reading process. Sometimes you can simply clean or polish a disc and it will work like new.
Scratches on CDs, DVDs, gaming discs and Blu-ray discs can cause problems, but store-bought discs should be the least of your concerns. Even though it can put a dent in your wallet, you can always replace a store-bought disc simply by buying a new one (unless it’s out of print, that is). But a bigger problem is when a disc you made yourself is scratched. For example, if you saved a bunch of digital photos to CD-R, and your computer will no longer read the disc, you stand to lose all the images.
The very first thing you should do with a bad disc is to make sure the foil layer on top isn’t damaged. If you hold the disc up to a light and look through it, damage to the foil layer will show up as bright spots shining through the disc. If the foil layer is damaged the disc is ruined. You can throw it away now and not waste any more time with it. (By the way, if you ever want to make an optical disc unreadable, scratching off some of the foil layer will definitely do the trick.) If the foil layer is intact you can try cleaning the disc.
Any soft cloth that’s safe for eyeglasses is safe for cleaning optical discs. A well-worn T-shirt is also safe. If a disc is particularly dirty, say from a soda spill, you should wash it in soapy water and dry it thoroughly before trying to play it. If a disc has greasy fingerprints on it, try rubbing them off with a soft cloth from the inside of the disc outward and not in an angular motion around the disc—doing so can create tiny scratches that cause tracking problems for the laser.
If a disc still has problems after a thorough cleaning, you should inspect the underside once again. If it’s in perfect shape, the problem could be a defect that you can’t see. A condition called disc rot can theoretically affect any type of optical disc. Even if you don’t play a disc, years of warming and cooling cycles can cause the bond between the foil and plastic layers to fatigue, resulting in a disc that can no longer be read. There’s nothing you can do to repair disc rot. Fortunately disc rot is not nearly as common as experts have warned, and sometimes a manufacturer will send you a new copy of a disc if you send them the defective one.
If a disc has visible scratches or hazy spots caused by abrasion, it’s worth trying to repair the damage. The easiest way to repair a disc, but not the cheapest, is to use a machine that’s made for the job. B&H has DVD/CD Repair Machines that make short work of restoring any disc that’s restorable.
These machines basically clean and polish the underside of a disc, which is something you could also do by hand. Just like using polish to remove scratches from a car’s finish, you can use plastic polish, car polish, metal polish or even toothpaste to remove scratches from an optical disc. You can also try Ikelite Novus Polish, which is made for removing scratches from acrylic domes used in underwater photography. Just rub a bit of the cream into the scratched area in a circular motion, let it dry and buff with a soft cloth until shiny. If one treatment doesn’t work, try applying it twice.
Another neat trick you can try with CD, DVD and Blu-ray discs that won’t play properly is to make a copy of the disc. Quite often scratched music and movie discs cause problems that you can hear and see with a play-only unit. But an optical drive in a computer can repeatedly attempt to read the data until it gets it right and, if it can, a new copy of the disc should play normally in any compatible player. If your computer can’t read a disc, try it in someone else’s computer. Sometimes that’s all it takes.