Keeping data CDs in the dark for two years isn't a good idea. According to the Dutch magazine PC Active some CD-Rs degrade in months, even at room temperature without sunlight.
PC Active tested data disks from 30 manufacturers that were recorded 20 months ago. Several data CDs developed serious errors, or became virtually unreadable.
A graphic shows what can happen when CD-Rs are left too long in the drawer. The colours of the CD-R on the right indicate the severity of the errors; white specifies that the disk can be read well, red that it can't be read.
Some manufacturers claim that their CDs are good for at least 10 years, if you keep them out of the sunlight. Some even say that their CDs will last up to a century; but the Dutch test seems to suggest that CD-R is the wrong medium to store photos, music or data files for posterity. It makes you wonder how the various DVD disk formats stack up.
PC Active believes that different dye systems used for CD-R disks are the root of the evil. Some dyes are more stable than others. The most stable dyes are used primarily in premium brands. A combination of heat and light and marginal drives also contributes to the deterioration. Higher recording speeds are not the issue.
PC Active tested 30 brands, some of them sold exclusively through a Dutch chemist chain. Unfortunately, the article seems to focus on white label CD-Rs, and doesn't mention any premium brands that performed well. ®