OK, here are my mixed results after 9 hours of baking at 135 degrees F, then letting it cool down for about a day before I got around to trying to play it......
Very sorry. I never personally spool before baking, and out of many hundreds, maybe thousands of baked Ampex 1/4 reels, exactly one had the oxide separate cleanly like that after baking. My guess is that you'd have had the same problem after baking.
Sticky shed is usually known on tapes that have backcoat, and apparently manufacturers started using urethane in the binder for the backcoat and the oxide layers. My feeling is that even among certain manufacturers and tape "models" that there is a wide variation in decomposition. I am guessing there is batch inconsistency as well as storage differences. In the USA, Ampex is most cited, but also 3M, Agfa, etc. Other tapes may have other problems that may make them seem sticky, and baking is not recommended.
There is one fellow who says to "simply" remove the back coat, which he says is the root cause of the problem. A few test demonstrations have apparently been successful, but he has yet to show a practical method of doing this.
Here are some references. I would probably start with the Richard Hess paper.
---Sticky Shed References from the 1980s-90s---
IASA Phonographic Bulletin #61, "Restoration of Tapes with a Polyester Urethane Binder" 1992
Studio Sound, May 1991 - Barry Fox's Business column, Sticky Shed Update
Studio Sound, December 1990 - Tape Life: An Era of Concern by Barry Fox
Audio, November 1990 - Archival Revival by Michael Stosich
Audio, July 1990 - Bert Whyte's Behind the Scenes column (I bake for Whales)
MIX, May 1990 - Philip De Lancie's Tape and Disc column "Sticky Shed Syndrome, tips on saving your damaged master tapes"
Recording Engineer/Producer, July 1988 - Studio Update:
Talkback: Binder Breakdown in Back-Coated Tapes by Scott Kent
JAES, April 1988 - Increasing the life of your Tape by Jim Wheeler, Ampex.
Broadcast Engineering, October 1987 - Preserving Magnetic Tape by Walter Davies (the LAST Factory)
IEEE Transactions on Magnetics, September 1985 - Kinetics of the Humid Aging of Magnetic Recording Tape, by H. Neal Bertram, Ampex.
---Other references---
The Ampex Patent
U.S. Patent 5,236,790
Richard Hess
Tape Degradation Factors and Challenges in Predicting Tape Life
ARSC Journal, volume 39, No. 2 (Fall 2008) page 240
http://www.richardhess.com/tape/history/HESS_Tape_Degradation_ARSC_Journal_39-2.pdfHess' personal site with tape degradation info for several tapes
https://richardhess.com/notes/formats/magnetic-media/magnetic-tapes/analog-audio/degrading-tapes/Sonicraft (New Jersey) on tape baking
https://www.sonicraft.com/tape-baking/Eddie Cilletti
If I Knew You Were Coming, I'd Have Baked a Tape!
http://www.tangible-technology.com/tape/baking1.htmlMike Rivers
Early article with caveats
https://mikeriversaudio.files.wordpress.com/2020/07/how-to-bake-a-tape_original_1990-article.pdfARSC (Association for Recorded Sound Collections)
Guide to Audio Preservation (CLIR pub 164)
https://www.clir.org/pubs/reports/pub164/British Library
Manual of Analogue Sound Restoration Techniques
https://www.bl.uk/help/manual-of-analogue-audio-restoration-techniquesIASA (International Association of Sound and Audiovisual Archives)
TC03 (general planning), TC04 (restoration guides)
https://www.iasa-web.org/tc04/audio-preservationWeb version free to public; PDF free to IASA members; paperback for a fee.