I learned this trick from Seth Winner 20 years ago or more (and I think he may have learned it from Tom Owen). I store all acetate tapes in a B-wind (after repairing all of the splices, leader tape, etc., and replacing all slotted hubs). Even if you return them to a normal wind for playback or transfer, it makes sense to store them in a B-wind permanently. As you note, they often have a smoother pack this way, and though the benefit may remain long enough to get a good transfer, it may not be permanent. I think what's going on is that the stresses on the tape that caused them to deform in the first place are now in the opposite direction.
I don't find that a B-wind does much for Mylar/polyester tapes.
Audio Engineer Emeritus
The Crane School of Music
SUNY at Potsdam, NY 13676
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From: Association for Recorded Sound Discussion List <[log in to unmask]> on behalf of Marcos Sueiro Bal <[log in to unmask]>
Sent: Tuesday, February 7, 2017 9:56:44 AM
To: [log in to unmask]
Subject: [ARSCLIST] B-wind for better pack
A few weeks back, my colleague Ana Marie showed me a "trick" whereby she gives a half twist to tapes suffering from poor pack while library-winding them. The resulting reel of tape, B-wound (oxide on the outside), often shows a much better-looking pack --so much so that this has now become standard practice for me. However, the benefit does not always remain (or at least not as strongly) after twisting the tape back into an A-wind for storage.
I was wondering if anyone else uses this "trick" and --more importantly-- what makes it work, and why the tape often reverts back to a poorer pack. Also, does anyone store tape B-wound?
Marcos Sueiro Bal
Senior Archivist, New York Public Radio
646 829 4063