CD-R shelf life refers to the length of time that a recordable compact disc will remain viable once data has been burned onto it. Top manufacturers like Mitsui, Verbatim, Maxell, Memorex and TDK claim that premium discs, with protective coating and special dyes, will last 50 or even 100 years.
Many industry experts, however, think that the unrecorded shelf life of a CD-R disc is more conservatively estimated to be between five and 10 years. One expert from IBM estimates longevity at two to five years.
The National Institute of Standards and Technology (NIST) published results of accelerated aging tests on CD-Rs and DVD-Rs in 2004. CD-Rs that used phythalocyanine dye and had a gold and silver alloy coating performed best. Overall, the study estimated that 13% of discs would fail within 50 years, if the media was stored under normal office environmental conditions.
NIST and the Library of Congress are now collaborating to determine the life expectancy of DVD-R media. They hope to develop a test that the manufacturers can use to assign an archival grade to their products.
Once a disc is burned, a laundry list of factors affects how long stored data can be retrieved. These variables include:
- Media quality: All CD-Rs are based on a thin, polycarbonate base. Any wobble or imbalancing of the disc -- caused, for example, by an applied label or out of level workstation -- can negatively impact the burning process.
- The type of dye used to protect the underside of the disc: This factor makes the most difference to the shelf life of a disc because the effect of sunlight can seriously impair longevity.
- Method of storage: Keeping discs in sleeves or stored upright in jewel cases when not in a drive minimizes the possibility of scratching.
- Storage environment: The ideal temperature range is 41-68, with humidity between 30-50%. Direct sunlight should be avoided at all times.
- Marking method: Only a felt-tip water based marker on the label side of the CD-R should be used, ideally on the clear inner part near the center. Permanent markers (like "Sharpies") should be avoided. Paper labels should always be applied to the jewel case, never to the disc itself. While manufacturers may sell circular adhesive labels that can be printed at the home or office, solvents in the paper, adhesives or inks can all degrade the disc. Uneven application of the labels can also cause the CD-R to wobble in high speed players, causing read/write errors or even damaging the player itself.