Cleaning and Handling CDs and DVDs
Cleaning and handling CDs and DVDs is a basic thing everyone should understand and practice. For one thing it helps to lengthen the life of the media which carries the message we would not like to loose.
But First a Bit Of Explanation
The recording on a CD and DVD disc is protected to some extent. It is held within the layer structure of the disc and is not on the surface. It is not immune to damage though as scratches can still mean a player may not be able to read the data within. A player does have error correction circuitry to counter some such damage or reading errors. Though if you have ever heard the sound skip or stutter and seen a video picture break up, you have just seen the results of the error correction circuitry being overloaded.
Under the printed label is a reflective surface needed to bounce the laser pickup into a sensor to read the disc. This side of the disc should not be written on or damaged in any way. Only certain types of discs may be written on and only with a special pen. If that reflective layer is damaged there is no way a player will be able to read the disc.
Taking care of discs also mean not leaving them out of their cases, stacking them directly with other discs or allowing them to collect dust and finger prints etc. Much the same thing applies as it did in the era of vinyl records.
If you need to clean a disc first lightly brush off any dust, mist the surface with your hot breath and use a soft tissue to wipe from the inner to outer edge, never around the disc. Look at the surface while reflecting some light, you should be able to see any surface deposits. If still there try the above again. If not successful you may just simply be looking at some sort of broad material imperfections.
Bad scratches may be able to be polished out. Restoration kits are available for you to do that. Still, I would think twice about just how valuable that disc is before applying some abrasive gunk and polishing away.
Apart from that, it has to be said that it would be better not to allow the damage in the fist place. If of course it could be prevented. Best though to keep any disc away from dirt, dust, water, heat and excessive sunlight. With the right care a good brand of disc can last for 100 years and still be playable.