Re: [ARSCLIST] Proper storage of mylar/acetate tapes

[Sarah Cunningham <shcunningham@xxxxxxxxxxxxxxx>]

Tom,

Try the AES-11id-2006 - AES Information document for Preservation of Audio
Recordings- Extended term storage environment for multiple media archives. Page
11 of this document has a great chart  "Suitability of storage environment for
media stability" that outlines the storage needs for these formats as well as a
few other carriers.

Sarah Cunningham


Quoting Tom Fine <tflists@xxxxxxxxxxxxxxxxxxx>:

> A client of mine is moving to new digs and has the opportunity to set up a
> better storage area for
> their tapes. This is a collection of 500 or so reels, all have been
> transferred to a managed digital
> storage system. About 400 of the reels are old brown-oxide acetate/mylar with
> a few odd cellulose
> base in the bunch. The rest are more modern backcoated types (about a dozen
> were trouble-era Ampex
> 456 and required baking before transfer).
>
> I read through the following:
>
> AES E-Library: Tape Storage Problems by Radocy, Frank
> http://www.aes.org/e-lib/browse.cfm?elib=283
>
> Imation document
> http://www.imation.com/government/nml/pdfs/AP_NMLdoc_magtape_S_H.pdf
>
> Australian government:
>
http://screensound.gov.au/preservation/audiovisual_terms/audiovisual_item.php?term=Archival%20Storage%20Conditions
>
> LOC:
> http://www.loc.gov/preserv/care/record.html
>
> There seem to be some conflicts about the following issues:
>
> 1. what humidity level is too low for acetate/mylar? And, what is the true
> optimum temperature
> range? The research done in the 50's by AudioTape (ie reaseach done by one of
> the manufacturers at
> the time the tape was being manufactured) indicates the 40-50 degrees F
> recommended in the LOC
> document may be too cold, especially at low humidity levels. The humidity
> level recommendations for
> older tapes seem to be in the 40-60% range, which is easily achievable in the
> client's new digs, but
> we want to make sure to get it right so the tapes don't curl any worse over
> time. My own experience
> in standard Northeastern US households is that acetate tapes hold up best (ie
> don't develop edge
> warp and terrible print-through) if stored in a cool, dry downstairs (with
> "dry" being, real-world,
> 60-70% humidity usually, sometimes lower in winter months and "cool" being
> temp range of about 55-70
> degrees F). Obviously we are going to avoid a swinging range of temp and
> humidity because that is
> damaging to tapes, according to all research I've read.
>
> 2. the temp/humidity levels appropriate for mylar seem a little different
> from backcoated tapes,
> but, can the backcoated tapes "live" ok in a mylar-centric environment? In
> other words, humidity and
> temp may be a bit higher than sometimes recommended for backcoated tapes. The
> client could store the
> backcoated tapes in a separate area, but my thinking is, we know what tapes
> have sticky-shed and we
> know they'll need baking before playing in any case. The other tapes are 30+
> years stable so
> unlikely not to be fine under the better-than-before conditions (ie from now
> on more constant temp
> and humiditiy).
>
> I should add, we only had one vinegar tape and it was determined that the
> content was non-valuable
> so the tape was destroyed. The sticky-shed tapes did have valuable content
> but I got a very good
> transfer so it's unlikely they will need to be played again. The client is
> more concerned about
> keeping the analog material as a backstop if the digital archive ever fails.
>
> Thanks in advance for your input. I am particularly interested in what
> storage conditions are being
> used for large collections of similar tapes.
>
> -- Tom Fine
>