Re: [ARSCLIST] Memorex CDs

[Mike Richter <mrichter@xxxxxxx>]

Don Cox wrote:
> On 14/01/06, Mike Richter wrote:
>
> > > Manufactured CDs are much less likely to change than burned CDs.
> >
> > Not necessarily. Major and minor publishers have used inks which
> > corroded the discs. In addition, I have seen arguments that the life
> > of a well recorded CD-R should exceed that of a commercial recording.
> > Frankly, I find that unpersuasive: we know neither lifetime reliably
> > so any assertion that one is longer than the other strikes me as
> > compound guesswork.
>
>
> A moulded pit in the plastic seems likely to be more permanent than a
> light-induced chemical change which can always be further changed by
> more light. 

I agree - and therefore said that I found the argument unpersuasive. 
But, again, we have no supporting data.
> > > Including CDs that cannot be read with standard players today.
> >
> > A disc compliant with the red book and well written can be read in any
> > player compliant with the standard. 
>
>
> But not if it has aged badly. Future forensic players should be able to
> extract information from damaged or faded disks which cannot be read by
> normal players on today's market.

Surely - in fact 'unreadable' discs can be read today by agencies with 
the tools and methods to do so.
> What does surprise me is that nobody has yet set up a business to remove
> corroded aluminium coatings from aging disks and re-coat them. There has
> to be a chemical process which will remove aluminium but not affect the
> polycarbonate.

It's an interesting hypothesis and there are certainly agents which will 
remove the acrylic lacquer and the metallizing layer (aluminum only in a 
pressed disc, irrelevant to this subject). There's little chance that 
such a process would leave the surface so smooth that replating it would 
allow recovery of the information without extraordinary tools.

Mike
--
mrichter@xxxxxxx
http://www.mrichter.com/