The British Institute of Recorded Sound (part of the British Library)
devised a clock-like mechanism to very slooowly unwind audio tapes that
suffer from oxide flaking. The process apparently has some merit. I
tried shuttling (running the shuttle function at a creep) a small reel
of 1/4", AMPEX 456 that suffered from this problem and wasn't that
successful. This was before I heard of the British Library's clock
mechanism. So, apparently, the slower one can unwind the layers of a
tape suffering from oxide flaking or shedding, the better. I have often
wondered if applying a chemical would help this process. Where I had
access to potential candidates for some experimentation, the corporate
environment wouldn't allow it.
As far as tape stocks suffering from oxide flaking or shedding:
I have mostly run across the problem with AGFA, BASF and AMPEX stocks.
Some early brands (mostly the cheaper ones as Richard pointed out) of
acetate base tape have given me oxide shedding fits. I have experienced
oxide shed with Scotch 201 but almost exclusively at the edges of the
reel (both 1/4" & 1/2"), leaving the modulation intact. Scotch 206 used
to be the the one formulation that I could count on but no more. I have
encountered enough 206 in the last few years that has gone SS, that I
now check the condition of every brand and type of tape.
Corey Corey Bailey Audio Engineering
On 12/6/2016 6:01 PM, Richard L. Hess wrote:
> Gary, I liked that you think I can SHED more light on it!
> On a more serious note, I have no answers--I even have fewer questions
> to try and get answers.
> The only bad shedding I've seen have been on Concert and other
> lower-end tape, although some 201 has been slightly problematic as one
> of you mentioned. I have yet to experience this with 206, but so far,
> my 207 seems fine.
> I just did another 54 reel project and all played fine. But the tape
> and boxes did not appear to match.
> There are so many factors, I don't know where to begin. I've asked Ric
> Bradshaw if he has any thoughts, but he's getting farther away from
> that phase of his life, and his experience was mostly at IBM on data
> Just a reminder about a great 3M tape resource:
> On 12/6/2016 13:28, Aaron Coe wrote:
>> I’ve also encountered Scotch 206 tapes de-laminating (oxide layer
>> separating from the substrate). I believe these are from the 1970s,
>> but not sure. As of right now there is no treatment that I’m aware
>> of, but I know Richard Hess has been investigating it though.
>>> On Dec 5, 2016, at 8:57 PM, Gary A. Galo <[log in to unmask]> wrote:
>>> Hi Dan,
>>> I'm sure Richard Hess can shed further light on this, but my
>>> experiences with tapes in the Crane Recording Archive is that the
>>> sticky-shed tapes are not the ones that are shedding oxide (by
>>> "delaminating" I assume you mean that the oxide is peeling off the
>>> tape). My entire analog career at Crane was on Ampex tape, mostly
>>> 456, but also some 406, 407 and 457. None of those that I've baked
>>> and transferred have oxide shedding problems.
>>> The worst offender in our archive, for the problem you describe,. is
>>> probably Scotch 201 from the mid-late 1960s. 201 was 3M's last
>>> acetate formulation and it's one of the most problematic tapes I've
>>> encountered. But, being acetate, you don’t EVER want to try baking
>>> it. Besides, the only tapes requiring baking are back-coated tapes,
>>> and none of those are acetate, as far as I am aware. Most of my
>>> problems with 201 are around splices - the physical cutting of the
>>> tape seems to have stressed the tape so it's more prone to oxide
>>> flaking there than elsewhere.
>>> Gary Galo
>>> Audio Engineer Emeritus
>>> The Crane School of Music
>>> SUNY at Potsdam, NY 13676
>>> "Great art presupposes the alert mind of the educated listener."
>>> Arnold Schoenberg
>>> "A true artist doesn't want to be admired, he wants to be believed."
>>> Igor Markevitch
>>> -----Original Message-----
>>> From: Association for Recorded Sound Discussion List
>>> [mailto:[log in to unmask]] On Behalf Of Dan Gleich
>>> Sent: Monday, December 05, 2016 8:00 PM
>>> To: [log in to unmask]
>>> Subject: [ARSCLIST] Baking Tapes and Beyond
>>> Dear Colleagues
>>> Over the course of a large digitizing project of mostly 1/4” tapes,
>>> we have run across a few tapes that will actually delaminate when we
>>> attempt to play them, in some cases even after the usual low level
>>> heat treatment that renders “sticky” tapes playable for transfer.
>>> We have a lot of recordings on Ampex 406, 407 and 456, and 3M 226
>>> that I expect we’ll need to treat in order to be able to play them,
>>> but I’m wondering if anyone out there has experience with saving
>>> tapes that are actually peeling apart.
>>> Any help would be most welcome. Thanks.
>>> Dan Gleich
>>> Dan Dugan Sound Design