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Hi Tom,

Thank you for starting this excellent thread.

I wanted to chime in with two brief points that I think havenıt been
covered yet:

1.  When encountering a moldy tape, you need to weigh the cost of mold
    removal against the risk of VS when segregating and storing moldy
    tapes in sealed bags (with or without a desiccant like silica gel).
    As noted by others, VS seems to be a function of storage temperature,
    therefore moldy tapes that are stored and sealed should be stored in
    a ³cold² environment to minimize the risk of VS.  If you can afford
    to do it, it is still best to remove the mold.

>
>Another distressing datapoint ... This is the second batch of late 1950s
>Audiotape acetate-backed
>tape I'm dealing with that has become very brittle, like most of the
>plasticity has dried out of the
>backing. I suspect this is made worse by over-dry storage conditions
>intended to somehow "prevent"
>or "mitigate" sticky-shed in later tapes (and remember that there is no
>proof that dry storage does
>either). I wish some scientists would do some chemistry on acetate tapes
>and come up with better
>storage recommendations. There are millions of acetate tapes and films
>being stored under the same
>"keep it super-dry and cold" mandates that are imposed on polyester media


2.  I have had reasonable luck ³de-brittling² acetate tapes by placing
them 
    in a cool humid environment.  For example, I use a clear plastic
    container and place a tray of distilled water on the bottom, and then
    suspend the brittle reels above the tray.  The container has openings
that
    I can adjust to roughly control RH - I target a 60-70% RH.  I do this
in 
    a room that is in the low-60s F and dark.  I monitor and check the
tapes 
    daily - I worry about activating any potential mold spores. The tapes
will 
    slowly become more pliable over the course of 1-4 weeks (every tape is
    different, some do not respond).  Once reasonably pliable, I remove
the 
    tapes and let them acclimate to the RH of the studio for about a week.
 
    Certainly not a production method because it takes time and
monitoring, 
    but it generally helps.

    I do not humidify tapes that have known mold exposure.


    From a chemistry point of view, this doesnıt seem like it should work,
    so Iım not sure what mechanisms are at play.

    The suggestion by John Schroth of using camphor is very interesting,
    and I may try this - although I need to find the right container.

    Would love to hear if anyone else has tried ³humidifying² acetate
    tapes - intentionally or otherwise.


~ Eric


_________________________

Eric Jacobs
Principal
The Audio Archive, Inc.
1325 Howard Ave, #906
Burlingame, CA 94010

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Disc and Tape Audio Transfer Services and Preservation Consulting

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