Re: [ARSCLIST] S-S-S and tape baking

["Marie Azile O'Connell" <marie.oconnell@xxxxxxx>]

Hi Mike

I sent you an email with pictures from my home email.  Wouldn't work here for
some reason.

Cheers
Marie

Quoting Mwcpc6@xxxxxxx:

> I tried to post this on the [Ampex] list but it may not appear because of 
> creeping HTML content in AOL mail. Others here might be interested in the 
> anecdotal data.
> 
> About twelve years ago I salvaged tape from a local studio's radio commercial
> 
> masters for editing transfers of some oral history material for cassette 
> access. The tape was in Ampex 291, 414, 405; 3M 201, 175, and many white
> boxes, 
> various lengths. 
> 
> I found that black oxide back coated tape was useless because of SSS, 
> non-back coated tape was fine, regardless of oxide shade, and brown oxide
> back coated 
> tape seemed OK. At the time I thought the SSS was a function of the oxide, 
> not the backing so I interspliced the scraps of brown coated and non-back
> coated 
> tape.
> 
> Now I am trying to use these same edited reels to make mp3 files for access.
> 
> Now the brown oxide back coated tape has serious problems.
> 
> Back then, the black oxide back coated tape oxide stuck to the heads and 
> squealed, but did not adhere to the coating. Now some of the brown oxide tape
> 
> still plays fine, leading me to start rewinding one reel before checking.
> Before I 
> realized it, about half the oxide of that section had transferred to the 
> backing.  Baking that reel recovered the part that had not been damaged, but
> after 
> baking the oxide on the damaged section fell off in strips!
> 
> After that incident, I have been baking all back coated tape, whether it 
> seems to need it or not.
> 
> Also the adhesive of the splices on the back coated tape are softened and 
> they come apart during rewind, even on back coated tape that plays OK, while
> 
> splices on the non-back coated tape in the same reel made at the same time
> with 
> the same splicing tape are holding just fine.
> 
> Baking these composite reels 12 hours at about 60C (dehydrator) recovers the
> 
> back coated tape without damaging the uncoated tape or the reels (7" plastic,
> 
> various designs) and even seems to harden the splices in the back coated
> tape.
> 
> This relates to the question of whether it is the oxide binder or the backing
> 
> that is responsible for sicky-shed syndrome. It seems that the backing alone
> 
> is enough to cause tape deterioration, though it may take a decade or more 
> longer to have its effect. The completely different behavior of the splicing
> tape 
> on back coating and plain base may be interesting also.
> 
> Obviously mixing types of tape on a single reel is not good practice and 
> nobody on this list would do that, but this provides some idea of the wide 
> variation of tape condition over time even under identical storage conditions
> (on the 
> same reel).
> 
> Mike Csontos
> 


Marie O'Connell
Sound Archivist/Sound Engineer/Sound Consultant
Center for Oral History & Cultural Heritage
University of Southern Mississippi
Phone: 601-266-6514
Mobile: 601-329-6911