Re: [ARSCLIST] Tape binder heals itself?

["Peter@xxxxxxxxxxxxx" <lists@xxxxxxxxxxxxx>]

Richard:

We have done quite a lot of research in this area and developed a process a
number of years ago called "Cold Desiccation" to deal with binder-base
separation in magnetic tapes.  The process is quite effective.   Jim Wheeler
confirmed that Ampex had noticed similar results as a side effect of some
other testing they had done when he worked there but no one had pursued the
phenomena at that time.

The basis of the treatment is to isolate the tape in a sealed environment
with low temperature (NOT freezing) and very low humidity conditions.  This
is multi-step process and is not a "quick fix" solution like baking as it
can take many weeks or months to be really effective.

This particular procedure is not applicable to acetate base tapes as the
humidity we use is very low.   On the other hand, simply lowering the
humidity conditions somewhat in a storage environment over a long period of
time can have a similar but not as strong or lasting effect.  This gentler
effect can be applied to acetate base tape.  One note of warning: since the
"healing" of tapes in slightly reduced humidity levels is not as strong as
the original bonds, they are more easily broken again and repeated exposure
to low humidity/ high humidity variations can eventually result in a
structure where binder-base readhesion is no longer possible.

The other issue that must be addressed with mitigating binder-base adhesion
is a phenomena that one manufacturer calls "puddling".  If a tape binder is
seriously hydrolyzed, the oligomer decay residue can build up to the point
where large amounts migrate to the tape surface and form a "puddle".  These
"puddles" must be removed or incubated back into the binder before tapes can
be treated with Cold Desiccation.  If "puddles" of oligomer residue are left
on the tape surface, the cross-linking forced by the process can harden the
"puddles" onto the tape surface and/or cause adhesion between tape wraps.
Since "hardened puddles" are now essentially the same polymer structure as
the tape binder, the "hardened puddles" become a permanent part of the tape.

Peter Brothers
President
SPECS BROS., LLC
(201) 440-6589
www.specsbros.com

Celebrating 20 Years of Restoration and Disaster Recovery Service

> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:ARSCLIST@xxxxxxx]On Behalf Of Richard L. Hess
> Sent: Sunday, May 18, 2003 2:47 AM
> To: ARSCLIST@xxxxxxxxxxxx
> Subject: [ARSCLIST] Tape binder heals itself?
>
>
> Well, fellow travelers through the mystery realms of tape failure, here is
> my latest puzzlement.
>
> Last December, I surveyed an archive in an air-conditioned library in
> Southern California.
>
> They did not have a recording hygrometer/thermometer. It was warm. They
> said it was sometimes humid.
>
> I opened MANY boxes of white-box tape which had clear
> leaders--not the kind
> you splice on, but rather the kind you get from the oxide coating/binder
> falling off.
>
> On most tape, clear leader from loss of coating is rare.
>
> I could stretch these tapes about 10% and rub the coating right off.
>
> I transferred one of these tapes in December and returned one CD-R copy to
> the archive immediately.
>
> I looked at the tape tonight and could not easily remove the oxide in the
> way I had last December. My home office is low-mid 70s F and runs
> typically
> between 30-40% RH.
>
> Anyone have any thoughts on this other than the library needs a recording
> hygrometer/thermometer?
>
> Anyone seen this "clear leader" syndrome?
>
> There is no budget to transfer > 1000 reels of this white box tape which
> was my recommendation (and it was, by the way, not a self-serving one
> because I cannot dedicate the time that 1000 reels would
> take--that ends up
> being a full work year, more-or-less (probably more), with all the
> ancillary stuff you need to do).
>
> Thanks!
>
> Richard
>