Archived posting to the Leica Users Group, 2002/02/15
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]yes and no Jonathan, the studies are being done, but not completed, as far as I know. As you can see from your experience, less than ideal conditions will damage a CD (as they will film, prints etc). In this case, the freezing and thawing (+ maybe moisture) did the trick on the foil - the most fragile part. I attended a workshop last year with conservation scientists from the Canadian Conservation Institute looking at just this - care and longevity of optical and magnet media. below is a summary of what they said (they were still in the midst of their research project then). John Poirer may correct me on some of this - he was at the workshop two and has a more technical understanding of these things...) I put this together for another list, so hope it makes sense here: 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: 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. And labels of any kind are about the worst immediate cause 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! > -----Original Message----- > From: owner-leica-users@mejac.palo-alto.ca.us > [mailto:owner-leica-users@mejac.palo-alto.ca.us]On Behalf Of Lee, > Jonathan > Sent: February 15, 2002 10:34 AM > To: 'leica-users@mejac.palo-alto.ca.us' > Subject: [Leica] Archival nature of CD-R > > > > LUGers all, > > Some no-mane brand CD-Rs of mine that have been left in my car throughout > this Canadian winter have devloped small pinprick like defects > that prevents > their being read. These were home burned music CDs and I'm not > that worried > about them, but my photo CDs are burned on this same brand of disk. Is > anyone aware of studies on the archival nature of CD-R or CD-RWs and what > storage conditions are recommended for long term? > > Thanks > > Jonathan Lee > -- > To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html