Kino used our news submit to tell us "For far too long, people have deluded themselves into thinking CD's and DVD's are immune from deterioration and are a prime archival media. Read this study and be informed; optical disc media can be a very useful, high density storage media, but you must know their limitations and the word "archival" should rarely be bandied about in the same breath... flame suit on."
We have covered this story from time to time and it even has a name around here; "CD rot". Interestingly, Mr. Iraci describes it as "laser rot", but it means the same thing. The deterioration of the reflective layer that allows the disc to be read over time. It's nice to keep in mind that proper selection of media for intended longer term storage and even the way we store the discs themselves, can be critical. At any rate, why not take a look at this very professional scientific and in depth, 18 page article written by Mr. Iraci. Perhaps this is still a good topic for further discussion. The study has tested an impressive number of different medias for the susceptibility of laser rot. Here's the method they in this particular study as described in the PDF link above:
"Aging conditions
The samples were aged in controlled temperature and humidity chambers (ESPEC PRA-3GP) at 80°C and 85% RH for four intervals of 500 hours (21 days). The total aging time was 2000 hours (84 days). This is the harshest aging condition outlined in the aging standard2 and this condition has been used in previous studies. Since the aim was not to produce an Arrhenius type study (so that extrapolation could be made to predict lifetime values), the discs were aged at the harshest conditions to ensure that degradation would occur within the aging period, thus allowing a ranking of the discs in terms of stability. At the beginning and end of each aging interval, the discs were allowed to adjust slowly to the new conditions of temperature and humidity as indicated in the aging standard2. This was required to allow the substrate to equilibrate to the changed environment, preventing the formation of liquid water droplets inside the disc structure, curvature of the disc, and possible delamination of disc layers."
For one thing, it is certainly true that we cannot base our knowledge of this situation merely by industry funded studies and certainly, more independent studies such as this should be beneficial. Which type medias held up best in the torture chamber and what was the method of their manufacture? You will have to read to find out!
Source: Université¤t Mé¼nster
