Hi Tony,
The Image Permanence Institute (www.imagepermanenceinstitute.org) has this
to say on the dangers of CDs:
- 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"!
Stephen Gray
--On 25 March 2011 12:07 +0000 Tony Crockford <[log in to unmask]> wrote:
> On 25 Mar 2011, at 12:02, Steve Hull wrote:
>> Self-recorded DVDs can have a usable life of as little as 2 years
>> depending on the make.
>
>
> What does that mean please?
>
> Does it mean that after 2 years of sitting stored the data somehow
> vanishes? Or do you mean that if a DVD was in an out of a DVD reading
> device over a period of 2 years it will wear out? and how many insertions
> are we discussing?
>
> It seems a little vague to say there's a limit on usable life.
>
>
> --
> Tony Crockford
> [log in to unmask]
>
> ****************************************************************
> 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/
> ****************************************************************
Stephen Gray, Technical Support Officer for 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]>
For Information regarding Training and Seminars:
<[log in to unmask]>
Online advice documents: <http://www.jiscdigitalmedia.ac.uk/>
Hands-on 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/
****************************************************************
