Why don't I just pass on the notes and info I marked as being important for
me after I did this workshop (which I think has already been posted once
here...) :)
Remeber it was a practical affair, for people using and storing images on
optical and magnetic media. Archivists, photographers, Government info
systems people, film makers etc.
The advice was based on the current knowledge from people who are working in
the filed, conversing with colleagues worldwide, and actively involved and
testing themselves. This testing is not yet complete, but they have already
carried out testing for disaster recovery (eg soaking CD's, heat damage,
freezing etc etc).
Most of the info is from the workshop notes, but some is based on info
presented about their current testing for archival life of media,
accelerated aging, etc etc and so bear in mind I may have made my own
mistakes in transcribing this:
Here is some info I posted on another list, based on a recent workshop I
went on.
This was on the preservation of modern information carriers (optical and
magnetic media) run by two conservation scientists from the Canadian
Conservation Institute:
But basically, while testing is still being done, the following generally
hold true;
Best quality dyes and metallic layer in the disk - gold and phthalocyanine
eg Kodak Gold Ultima and one or two other brands. Some are also marketed as
"archival" this may not mean anything more, just marketed as such. Though
some makers may be making the protective top lacquer layer of toughened
material to resist scratching. Generally, you get what you pay for - better
quality control, disks that are properly balanced (+ less read error) etc.
Keep in reasonably low humidity and temperature. 10 to 20c is good (not
below -10c) and RH 20-50% (not lower than 10%) No great cycling in either
temperature or humidity, so constant.
Keep in the jewel case( polystyrene, polypropylene or polycarbonate), on
edge, no inserts if possible (not acid free). No labels etc (label and glue
can cause damage, and labels, even circular, increased read errors
dramatically). Non solvent marker if necessary on the case, and if on disk,
only on the very inner circle where the serial number is.
Store out of light - ie in the dark.
Don't scratch them!
Also, how they are burned also makes a big difference. Higher speed
burning/write can lead to more errors. So 1 or 2x write is often better.
Burn to ISO 9660 or whatever it is.
In fact one of the biggest areas with longevity apart from the above was
error level on the recording side, which depended on a number of factors and
got very complicated. Depending on your burning software, running the test
disk option actually tests it AFTER burning, to let you know how much error
there was (there is always some error). Also, over time, CD burners
deteriorate mechanically, introducing more error.
So, that's a quick overview. If there is stuff I forgot, I'll pass it along
They are still testing accelerated aging in different conditions, but I
think they were figuring at least 50-100 years following these type of
guidelines. Of course other factors come into effect such as machines to
read them and so on, but that is a slightly different topic.
Finally, make one for use and one or two for backup, stored separately -
fire, flood, earthquake and theft/vandalism cause more damage than ageing!
Tim A
