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It would be interesting to investigate ways to construct disks using welding, or even chemical bonding of layers, rather than glueing. I imagine this would result in more durable disks. 

Damien J. Moody
Information Technology Services
Library of Congress

>>> [log in to unmask] 06/03/05 1:17 PM >>>

To laminate is "to construct out of thin layers".  As such, DVD's are
laminated.  You can use other terms, if you prefer, but the issue is that
the construction consists of thin layers that are glued together (I believe
the NIST report has a section on construction).  According to reports, the
glue used is not made by the DVD manufacturers and was initially designed to
have a three year life-span.  That does not mean that the glue won't last
longer (most magnetic tapes only have 90 day warrantees).

I have not heard reports that DVD's are "delaminating all over the place".
I have heard reports of DVD's delaminating.  In the short run, I don't
really think delamination is a primary concern.  Not knowing the permanence
factors of the glue used, however, could be an issue if DVD's are stored for
extended periods.  No one really knows but, before assuming your DVD's are
going to be just fine sitting on the shelf for years, it might be an
interesting thing to investigate.

Hydrolysis can be dealt with fairly easily in magnetic tapes.  Discs are the
first modern recording medium that are glued together- just another factor
to consider.  How easy do you suppose it is to glue back together a disc
that has "unglued"?



Peter Brothers

> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:[log in to unmask]]On Behalf Of Mike Richter
> Sent: Friday, June 03, 2005 10:34 AM
> To: [log in to unmask]
> Subject: Re: [ARSCLIST] Testing DVDs
>
>
> At 09:16 AM 6/3/2005 -0400, [log in to unmask] wrote:
>
> >Can anyone confirm that glue failure is actually a problem and DVDs are
> >delaminating all over the place. I have subjected 15 brands of
> DVD-R discs,
> >7 brands of DVD-RW discs, and about 75 DVD movie discs to
> accelerated aging
> >conditions. The total amount of discs tested was close to 200.
> Not one disc
> >delaminated.
>
> Delamination should not be a problem on single-sided DVDs and I doubt that
> there is serious consideration of two-sided blanks for archiving (even
> DVD-RAM). Perhaps another term is intended here, but I am not aware of
> "lamination" in production of single-sided recordable DVDs.
>
> Mike
> --
> [log in to unmask]
> http://www.mrichter.com/
>
>