When it comes to storing and archiving information, there are two main types of media: optical media (such as CD and DVD discs) and magnetic media (such as VHS tapes and compact cassettes). Magnetic media can wear out over time, but CDs and DVDs maintain their original quality level from the first copy to the 500th copy and beyond. So can a CD or DVD disc ever become worn out?
To answer this question, we need to first take a look at how magnetic media works. Both VHS tapes and cassette tapes store sound and/or pictures by encoding data on to plastic film covered in a magnetic coating. With VHS tapes, the film is 1/2″ wide and with cassettes, the film is 0.150″ wide.
When the tape is played back, it passes over a playback head that rotates as it comes in contact with the tape. Tiny particles of dust and debris can eventually scratch the tape as it passes over the heads, resulting in a degradation of quality. The more times the tape is played, the more the quality will be affected.
With DVD and CD discs, this does not happen because of the technical differences between these formats. Disc drives do not have “heads” in the traditional sense, and are instead read and recorded by a highly accurate laser. This beam of light is the only thing to ever touch the disc. Discs also contain error correction which helps the player correctly decode blocks of data which it has difficulty reading.
While discs don’t “wear out” like magnetic media does but they do degrade. The recording layers are made with a dye that is extremely photosensitive that when exposed to UV rays over time cause the dye to deteriorate. Since the information of the disc is stored in the dye layer of a recordable disc it can cause failure in playback. ROM Discs like that of pre-recorded store bought CDs also can degrade. See Disc Rot. Conversely, when CD and DVD discs start skipping or encountering problems during playback, it is typically because of scratches and damage as a result of improper handling. Discs are very sensitive to scratches, scuffs, and fingerprints. They can also be damaged if left in direct sunlight or high-temperature environments. With a replicated CDROM or DVDROM, like that of pre-recorded disc, it is easy to simply buff out the scratches since the recording layer is stored on the metallic part of the disc and not the plastic.
The biggest reason for encountering read errors or playback errors with discs is because of poor quality media. Discs made with low-quality organic dye may only last 5-10 years before the data becomes unreadable, while high quality Archival CD-R media and DVD media have been shown to last up to 100 years or more in laboratory testing.
With recordable CD-R media, it’s best to pick a disc with a dark colored dye such as green, blue, and gold. All DVD-R media is purple, so pick a quality name brand such as Taiyo Yuden, Verbatim, Falcon Media, or US Digital Media. If it desirable to keep your stored information for a long length of time then it is advised to use only archival CD and DVD media such as available from Mitsui.
The best way to prevent any kind of data loss is to use good quality blank media and store it properly in a cool, dry environment with good packaging. As for discs wearing out from repeated usage like magnetic media, that’s simply not possible.
To learn more about optical media storage and technology, check out the CDROM2GO Resource Center which is full of articles and information about discs, equipment, printing, and more!