I wouldn't by any means assume that adverse storage conditions are
necessary for such a short lifespan, Tony -- I think you've been very
lucky! I have five year old CDs that have been kept perfectly soundly
(no pun intended) that have become at least partially unreadable.
In addition to all the problems that Stephen mentioned there's the issue
of the organic dyes that are used to record the data. Some are more
stable than others and you can be sure that the cheapest discs use the
least stable dyes. Note that we're talking CDs and DVDs that are burnt
on a computer or some other home or office device; discs that are made
at a DVD or CD publishing business from a glass master _can_ be much
longer-lived.
steve
On 25/03/2011 12:38, Tony Crockford wrote:
> On 25 Mar 2011, at 12:29, SR Gray wrote:
>
>> - Loss of disc integrity. Under adverse storage, possible defects are layer separation, lack of planarity, cracking, and pinholes. Large and rapid temperature and RH fluctuations can be particularly detrimental.
>> - Corrosion. May occur due to high RH.
>> - Mold [DVD rot]
>> - Poor air quality. Pollutants can cause corrosion of the metallic reflective surface..
>> - Light exposure
>>
>> On DVDs:
>> "DVDs are even more complex, consisting of two CDs bonded with an adhesive. The
>> polycarbonate supports form the outside layers of the laminate. Different DVD formats have different layer structures."
>>
>> None of this takes into account the risk of actually using CD/DVDs (who would be so foolhardy!) So to summarise. Depending on storage conditions data can indeed "somehow
>> vanish"!
>>
> eek…
>
> FWIW I have lots of Data on *Cheap* DVD's from 2004 and it's all still there…
>
> They've been stored in a big Case Logic DVD wallet on the shelf in my home office.
>
> I imagine the term "Under adverse storage" applies here.
>
> ****************************************************************
> website: http://museumscomputergroup.org.uk/
> Twitter: http://www.twitter.com/ukmcg
> Facebook: http://www.facebook.com/museumscomputergroup
> [un]subscribe: http://museumscomputergroup.org.uk/email-list/
> ****************************************************************
>
--
Steve Hull, Technical Support Officer, Moving Images
*JISC Digital Media - A JISC Advance Service*
/Still images, moving images and sound advice/
Free Helpdesk for UK Further and Higher Education:
[log in to unmask] <mailto:[log in to unmask]>
Online advice documents: www.jiscdigitalmedia.ac.uk
<http://www.jiscdigitalmedia.ac.uk>
Hands-on training: www.jiscdigitalmedia.ac.uk/training
<http://www.jiscdigitalmedia.ac.uk/training>
****************************************************************
website: http://museumscomputergroup.org.uk/
Twitter: http://www.twitter.com/ukmcg
Facebook: http://www.facebook.com/museumscomputergroup
[un]subscribe: http://museumscomputergroup.org.uk/email-list/
****************************************************************
