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Re: CDs, was DATs, Was Re: arsclist Duplicating casette tapes

Steve Green wrote:
> ----- Original Message -----
> From: Mike Richter <mrichter@xxxxxxx>
> To: <ARSCLIST@xxxxxxxxxxxxxxxx>
> Sent: Friday, August 09, 2002 2:54 PM
> Subject: Re: CDs, was DATs, Was Re: arsclist Duplicating casette tapes
> Mike Richter wrote:
> > Anecdotal reports are not to be dismissed, but neither are they the basis
> > for choosing an archival medium. For example, it is difficult to infer
> > anything about UV exposure on this test since the sunlight passes through
> > glass - essentially opaque to UV - before striking the disc. UV exposure
> > has little relationship to the environment of an archive (storage or in
> > use). Even the effect of heat is debatable: it will certainly accelerate
> > decay, but I have found no data which would lead to quantifying
> > acceleration of life test as a function of storage temperature.
> I didn't intend to jump into the fray and still don't have time to pursue
> this further, but I would like at least to disagree about the relevance of
> UV and heat. I would have to say that regular window glass is not "opaque to
> UV." One has only to walk past a bookstore window on Main Street and see all
> the book jackets completely faded to realize the effect of sunlight on
> printed materials. I'm not prepared to say how it might affect CD-R dyes.
> The reason many archives don't have windows (or unshielded fluorescent
> lights) is because of the effects of UV radiation on printed materials. I
> have seen reel to reel tape boxes stored on shelves adjacent to a window and
> the spine labeling was completely faded away (the tapes inside the boxes
> played fine). There is much published data on the effects of heat (and
> humidity) as it relates to the storage of paper and magnetic media. I can't
> say off the top of my head whether the same data has been published for
> CD-Rs but given that heat accelerates organic and chemical processes, cooler
> just makes sense to me.
> Cheers and thanks for the input,
> Steve Green
> Western Folklife Center

Sunlight is rich in infrared that causes heating. UV is there but not as
much. I believe that IR is the major source of sunlight degradation of
CD-R discs, since UV is generally filtered by glass including the rear
car window where many CD's have met their doom.

Many sources quote UV as the source of deterioration without providing
any concrete evidence. The ASTM wool test is used for CD-R longevity,
and its spectrum is rich in IR.

Media Sciences, Inc.

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