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.

-Aaron
_____________________
http://cuttingcorporation.com

> 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. 
> 
> Best,
> Gary
> 
> ____________________________
> 
> 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