[ARSCLIST] The person responds was Thin tape decay

[dsbardella@xxxxxxxx]

> To the person who wrote mm, please note it's µm
> not mm.

Indeed it is.  The fact is, most of that post was copied directly from a
IASA document, micro meter symbols included.  Somehow the symbol must have
been reinterpreted as mm when copied on the LISTSERVE.  I guess the lesson
is "let copier/paster beware".

Having the exact caliper spec for each tape product is fantastic.  But for
the purposes of prioritizing tape collections in a sizable audiovisual
archive,  I think that (when combined with the thickness of binder, backing
and oxide) 1.5 mil based tapes can reasonably be considered to meet the
IASA guide of 52 micro meters.

Best,

The Person

Daniel Sbardella
The New York Public Library for the Performing Arts
40 Lincoln Center Plaza
New York, NY  10023

212.870.1609

Association for Recorded Sound Discussion List <ARSCLIST@xxxxxxx> wrote on
08/02/2006 02:45:50 PM:

> Hello, Marcos,
>
> I think that there are no specific ratios that
> are useful for determining the degradation rate
> of magnetic media. My research of the literature
> and the anecdotal evidence seems to suggest that
> original manufacturing formulation and anomalies
> as well as storage conditions over its life can
> affect the tape more than its thickness.
>
> I also think that it's futile to try and save any
> tape for 100 years, but rather we should focus on
> saving the content. The more I read about even
> PET base films and especially
> polyester-polyurethane binders the more concerned
> I become about century-plus "shelf storage" of analog magnetic tapes.
>
> While a need to prioritize preservation
> reformatting (aka "copying") of magnetic media is
> important, I do not think it is an exact science.
> In general, I would start with tapes with known
> degradation symptoms, and do the oldest to the newest.
>
> Following standard storage procedures should
> hopefully preserve the tapes long enough to get them copied.
>
> I would transfer acetate tapes before PET tapes
> based on base film, but I would prioritize
> polyester-polyurethane binder systems, especially
> those that I have listed on my website (look
> under the tape aging subject heading in the TIPS and NOTES Blog section).
>
> And, yes, I would transfer 18 µm thick tapes
> before 50 µm thick tapes. The thinnest tapes (18
> and 26 µm nominal) do have a habit of pinning or
> blocking, but that may not be related to their thinness.
>
> To the person who wrote mm, please note it's µm
> not mm. Also, as you know when measured in µm the
> implication is that it is the total thickness of
> the tape, while the mil measurement implies a
> base film thickness. The two references that I
> provided earlier today at www.aes.org/aeshc/ give
> detailed information for the thicknesses of each
> layer for open-reel audio tapes.
>
> In Windows, you write µ [mu]  as ALT-0181. or,
> conversely, you can call µm's micro metres or microns.
>
> Cheers,
>
> Richard
>
> At 10:24 AM 8/2/2006, you wrote:
> >Greetings
> >
> >Was wondering whether anyone on the list knows of any hard data out
there
> >(or even substantial anecdotal evidence) that shows that thinner tape
decays
> >faster, and to what kind of physical decay thin tape is most susceptible
as
> >time goes: cupping/curling, brittleness, shedding, etc. And even (and I
know
> >this is asking much) whether, say, 0.5 mil is "twice as bad" as 1 mil,
or
> >"four times as bad", etc. This is not playback-related; rather, picture
two
> >reels of the same formulation but different thicknesses, sitting side by
> >side for a few years.
> >
> >Will appreciate any information.
> >
> >Thanks much
> >
> >Marcos Sueiro
>
> Richard L. Hess                   email: richard@xxxxxxxxxxxxxxx
> Aurora, Ontario, Canada       (905) 713 6733     1-877-TAPE-FIX
> Detailed contact information: http://www.richardhess.com/tape/contact.htm
> Quality tape transfers -- even from hard-to-play tapes.