Re: [ARSCLIST] Thin tape decay

["Richard L. Hess" <arclists@xxxxxxxxxxxxxxx>]

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.