The increased temperature generated by sunlight will accelerate the degradation or breakdown of the dye layer (recording layer) of the disc. The broad spectrum of unfiltered sunlight, infrared to ultraviolet (low frequency to high), can impart heat to the disc.The sunlight’s ultraviolet photons (the higher frequency of the sunlight spectrum) have enough energy to produce a photochemical reaction, altering the optical properties of the dye (recording layer) molecules.These areas will then result in errors when read by the laser.ĭirect sunlight to R discs is harmful for two reasons: As a result, some, or all, of the unmarked areas in the dye could be read as marks, depending on the severity of degradation. Deterioration of the dye makes it less transparent. Prolonged exposure to sunlight or other sources of UV light can significantly increase the degradation rate of the dye (recordable) layer in R discs. Light effects on ROM discs, therefore, are considered negligible. To our knowledge, there is no report on the potential impact of this kind of material change on the playability of the disc. Degradation effects would likely be in the form of “clouding” or “coloring” of the polycarbonate. Any effect of light on the disc would involve degradation of the polycarbonate substrate (plastic) and would become noticeable only after several decades of exposure to daily storage facility lighting or sunlight through windows. 5.1.2 Light ExposureĪlthough the effect of light on ROM discs over time is not known, the effects of long-term exposure to light (e.g., UV, infrared, fluorescent) under ambient intensity, such as room lighting, are generally thought to be so minimal that light is not considered a factor in the lifetime of the ROM disc. Until testing is done to measure the effects of freeze-thaw cycles or long-term freezing, the benefits or harmful effects will remain uncertain. There may even be a benefit to uninterrupted freezing of a disc for an extended period.
Freezing and thawing may create harmful stresses in the disc because of differing expansion rates of the layers, but it is unclear how much this stress might affect the disc. Given the absence to date of relevant testing, the precise effects of storing CDs and DVDs in freezing temperatures are not yet known. This minimizes stress from frequent temperature changes. Discs used frequently should be stored at a temperature similar to that of the environment in which they are to be used. Leaving the disc in its packaging will allow gradual acclimation to a changed environment. A significant, abrupt temperature change will cause greater stress than a gradual change. If stored at a very low temperature relative to the user environment, the disc should be gradually acclimated to the environment in which it will be used to reduce stress and moisture condensation. Table 3: Recommended storage parameters from different sources
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