亂入，"相變材質" 怕 ："熱" "紫外光"

The phase-changing film is affected primarily by heat, but ultraviolet (UV) light may also be a factor in the aging process. (相變材質主要會被"熱"影響，但 "紫外光"也會) The combination of high temperature and UV light may further accelerate the aging process. (高溫 + 紫外光會加速老化過程) The combination of high temperatures and high relative humidity will also most likely accelerate the aging process, just as it does with the organic dye used in R discs. (和 R 一樣，高溫 + 高濕度也會加速老化)...

The data on the phase-changing metal alloy film layer can be erased and rewritten to a limited number of times (about 1,000 times for RW discs and about 100,000 times for RAM discs). This rewriting does, however, affect disc life expectancy; RW or RAM discs archived after the first recording should have a longer life expectancy than those that have undergone several erase-recording cycles. (覆寫會影響預期的壽命，寫一次比重複寫入幾次後的預期壽命高) Given the normal degradation rate alone, the life expectancy for RW and RAM discs will be less than that of R discs. (依照正常的速度，RW 與 RAM 的預期壽命較 R 低) Add to that multiple rewrites, and the life expectancy can be even less. (重複寫入後，預期壽命更低)


參考：
4. How Long Can You Store CDs and DVDs and Use Them Again?
http://www.clir.org/pubs/reports/pub121/sec4.html

NIST：
Care and Handling of CDs and DVDs —A Guide for Librarians and Archivists
http://www.itl.nist.gov/div895/carefordisc/CDandDVDCareandHandlingGuide.pdf