The cd-r media longevity / permanence equation is a very difficult to try and understand fully.
Several factors can play into the cd-r media longevity limits. These factors include, but are not necessarily limited to:
- permanence of the dye (thermal, oxidation
- reflective layer properties (oxidation resistance, reflectivity values)
- quality of the disc moulding (i.e. process quality)
- label side scratch resistance
- substrate optical performance
- geometrical quality (even thickness, eccentricity)
- initial burn quality (many sub-factors including statistical error
count, jitter, etc)
- bending, flexing and other geometry changes
- high speed roation secondary effects (cracking, shattering)
- temperature (high/low and rapid changes)
- relative humidity (esp. high and rapid changes)
- UV/IR radiation
- pollution/gases (NO2, SO2, ozone, ionisation content)
- solvents (grease from fingers, alcohol derivates from markers, etc.)
- biological risk factors (like fungi growth)
There has been various tests about cd-r media quality and some small initial tests about longevity. Even the latest of these are from 1999-2000 (that I know of).
So, for current very cheap media, using very cheap burners and very high speed recorders and unspecified storage conditions, what is the longevity of a CD-R?
Nobody really has data that I know of about this issue, but my experience combined with what test I have read, would suggest a lifespan from a couple of months (the really problematic cases) up to at least ten years or more.
But honestly, nobody really knows (AFAIK).
If we assume that manufacturer claims are true, best 'accelerated media aging' tests are somewhat accurate and that current cd-r media quality is not inferior to those tested in 1996-2000, then I would guess that the best media (when burned/handled properly) could indeed last up to 100 years.
However, that sentence contains a lot of big IFs.
PS I think this question has very serious implications to data storage professionals, conservation/archival specialist, medical storage system professionals and the like. A lof of the information that is stored on CD-Rs absolutely must be able to be retrievable even after 10+ years.