ILAT Digest - 8 Sep 2005 to 9 Sep 2005 (#2005-173)

[Robert Leopold]

Phil,

Hard data on the life expectancy of gold compact disks is available in the 2004 study published in the Journal of Research of the National Institute of Standards and Technology entitled "Stability Comparison of Recordable Optical Discs*A Study of Error Rates in Harsh Conditions" -- 

http://www.itl.nist.gov/div895/gipwg/StabilityStudy.pdf

The study concludes that "The life expectancy of optical media will not be the same for all brands of discs. In a CD-R comparison (see Fig. 3), sample S4, which uses phthalocyanine as the dye and a silver and gold alloy as a reflective layer, is far more stable than any of the other samples during both the temperature/humidity and direct light exposure tests."

We use Mitsui Archival Gold CD-Rs, which fit the profile of "sample S4" in the NIST study: a gold reflective layer and phthalocyanine dye. We create two copies of every compact disk (a master copy and a reference use copy). A third version of every file is stored on a removable firewire hard drive and a fourth version is stored off-site on magnetic tape. 

Robert

Robert Leopold, Ph.D., Director
National Anthropological Archives
Human Studies Film Archives
Smithsonian Institution

Visit us online: www.nmnh.si.edu/naa