Hi Eric:
Is this acetate-backed tape for sure? The description makes it sound that way. If it is, I recommend
you try humidifying it for a while, let it get thoroughly humidified, and then play it in a
relatively warm environment. All of that might make it less brittle, and also it might curl less as
it goes through the guides. Just a theory, but in my experience, acetate will behave better if it's
not super dry. I don't know of a great way to humidify it. Maybe leave it in a commercial greenhouse
for a few days? Not the paper box, of course.Watch out for mold, too, there may be spores all over a
greenhouse. Certain molds grow on and eat acetate, I know this for a fact. So maybe put it in a
sealed oven at relatively low temp (maybe 100-120 degrees F, maybe less) with a water source that
can evaporate and infuse the acetate over a time period? I'd experiment with a junker reel first! I
can send you some edge-curled but not vinegar Scotch 111 to play with. Can't say if it would behave
exactly the same way as the Japanese tape.
By the way, there were several articles over the years in the SMPTE Journal about the long-term
problems and breakdowns of cellulose (acetate) base for films. I assume the same problems and
mechanisms described apply to thinner-base magnetic tapes. A lot of SMPTE Journals are online at
archive.org, but maybe not the later era of which I speak (articles appeared in the 1980s).
-- Tom Fine
----- Original Message -----
From: "Eric Jacobs" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, January 29, 2016 7:13 PM
Subject: [ARSCLIST] playback of disintegrating open reel tape
We have a 1/4-inch open reel tape (TDK Synchrotape ca 1966 Japanese stock)
that is quite literally disintegrating and cannot hold any tension. The
very slightest amount of tension causes the tape to snap. The tape cannot
even hold a leader without snapping. Weıve turned the tape tension way down
on our Studer A820, but it canıt be pulled through the transport without
snapping.
The tape is heavily curled along the edges (only the center 25% is flat) and
is anything but straight from exposure to presumably high temperatures over
the past 50 years. The outer wraps have bonded to each other. We can deal
with the edge curl and the age-induced country-laning by using a custom
mechanism that gently increases the tape wrap around the PB head (forces the
tape flat) and additional edge guides fore and aft of the PB head that keeps
the tape centered on the head. We can even separate the outer wraps, albeit
in 1-inch segments that would need to be spliced together this seems like
a bad idea, but I donıt see any other choice if we want to get past the
outer wraps.
But itıs the fragility of the tape (lack of tensile strength) that is the
central issue. If it were possible to ³back² the tape, it might keep it
from snapping. But how do you efficiently and reliably ³back² 1200 feet of
tape that snaps with the slightest bit of handling? And what do you back
the tape with? Splicing tape? It might be easier to apply backing to the
centerline of the tape rather than the full width because of tape shrinkage
and edge distortion, but then the resulting tape pack would probably be
quite poor, especially if the backing doesnıt stack precisely on top of the
previous wrap. Also, a narrow backing (like cassette splicing tape) may or
may not affect the ability to force the tape flat at the PB head essential
for a quality transfer.
Looking for ideas and suggestions.
~ Eric
Eric Jacobs, Principal
The Audio Archive
1325 Howard Ave, #906, Burlingame, CA 94010
Tel: 408-221-2128 | [log in to unmask]
www.theaudioarchive.com <http://www.theaudioarchive.com/>
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