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RE: [AV Media Matters] arsclist Scotch 176 adhesion problems

"Richard L. Hess" wrote:

>I dug out a 1976 reel of Scotch 176--or at least that was what the box
>says. I was going to transfer it to DAT (and ultimately to CD-R). I
>playing it and I saw layer-to-layer adhesion. It's not sticky shed. There
>is no residue on guides, but rather some of the oxide may be attaching
>itself to the back of the tape. I stopped playing as soon as I noticed (it
>didn't happen for the first ten minutes of the tape). There are a LOT of
>splices in the tape so it may not be a homogenous type.
Be sure that the problem is not one of splicing tape adhesive oozing and
affecting ajacent layers of the tape.

>Is it sticky shed? Is this a bakable disease? Will baking hurt?
It is not likely sticky shed, but the problem may be related to the original
lubricant that was included in the oxide mix when the tape was made.
I've seen cases where this has dried out, leaving a tape that squeals like
a stuck pig when you try to play it.  Occasionally you will see a white
powdery residue, probably the dried out lubricant.

Because of the extended high humidity storage, I would be inclined to try
baking cycle to be sure that all excess moisture is removed from the tape.
Baking is not a cure for your problem, but it may help to reduce the
adhesion which doubtless has been magnified by the humidity conditions.
The moisture has had a long time to permeate the tape backing, binder
and oxide.

Baking is suspected to be a finite process that produces some irreversable
changes each time it is done, so it should be done with care using minimum
times and temperatures to get the job done.  You will probably need to clean
and re-make every splice after baking.  As a matter of fact, you probably
need to do that anyway!

... Graham Newton

Audio Restoration by Graham Newton, http://www.audio-restoration.com
World class professional services applied to phonograph and tape
recordings for consumers and re-releases, featuring CEDAR processes.

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