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Re: [ARSCLIST] Can Magnetic Tape Be Frozen?
At 11:56 AM 12/1/2004 -0500, Watsky, Lance wrote:
This is being posted for Beth Delaney, Nederlands Institute for Sound and
Vision
"Can anyone tell me if it is acceptable to freeze magnetic sound film? I
don't seem to find in any literature that this is not a good idea. Often
the literature states that it is recommended to "freeze acetate film", not
differentiating between acetate image material and acetate magnetic sound
film."
I personally believe that it is probably not recommended, but I wanted to
check with the ARSC folks, before responding back to Beth.
James, everything that I have heard points to your personal belief being valid.
The reasons that I've heard is that many tapes were made with
fatty-acid-based lubricants which do not respond well to freezing. While we
cannot be sure that a given tape was or was not made with a
fatty-acid-based lubricant, the prudent course is to not freeze any tape.
With that said, we have two different deterioration mechanisms working:
(1) The known danger of "vinegar syndrome" in acetate base films -- a
process that appears to be catalyzed by the iron content of the coating and
exacerbated by the typical steel cans in which film was commonly stored. My
personal belief is that we see this more in film than in audio tape for
several reasons, including the larger amount of acetate present (the
basefilm is thicker), the greater width of the medium (allowing for more
buildup of acid in the centre), and the lack of the traditional cardboard
box for audio tape which possibly acts as a molecular-sieve, absorbing the
acid which the tape releases.
(2) The potential risk of damage to the lubricant by freezing.
If I had a collection of items that were suffering from (1), I would be
tempted to risk (2) to arrest (1), but that is certainly not an official
stance or officially sanctioned by anyone, just my opinion. We know (1)
will destroy the elements. We don't know the long-term risk of (2).
The following is not for the squeamish:
The fatty acid used in at least some tape manufacture was sperm whale oil.
Cheers,
Richard
http://www.richardhess.com/tape/
1-877-tape-fix
Aurora, Ontario, Canada