Re: ancient tape squeak

[pk@mainstring.win.net (Pat Kirtley)]

PainPete@aol.com wrote:

>>This problem can occur under certain circumstances even with
>>well-adjusted machines and high quality tapes. But there is a lot of tape
>>made in the mid and late 70's that is now shedding like crazy due to
>>binder formulation problems. That's a widespread problem. 
>
>
>I'm not advocating this, but I've heard annecdotal evidence that with old
>reel tapes with this problem, baking them (yes! in the oven!) stabilized 
>the
>binder enough to make a transfer to newer tape. Time and/or temperature
>information is missing from this story, but I bet it's well below what's
>required to melt plastic!
>

and Kim Corbet wrote:

>....okay, this sounded bizarre when I first heard about it, but I believe 
>Bruce Richardson (73422.3357@compuserv.com) had a recent studio project 
>where he had to salvage an archiv of ancient tapes and used a, get this, 
>baking process in his kitchen oven...that somehow re-applied the material 
>to the tape.  I don't know temps or other details, but I'm sure 
>he'd be happy to share his family recipe.


Yes! I've heard of this technique before too. I believe the method was
originated by an archivist at the Library of Congress. I went searching on
the web for references and found this at:

http://sul-server-2.stanford.edu/byauth/wheeler/wheeler2.html

"Regardless of what format is used, the following are the most common tape
problems:

   1.Sticky residue or powder on tape, which makes it difficult to play 
the tape. 
   2.Binder degradation (oxide flaking off the basefilm). 
   3.Physical damage due to poor tape recorder maintenance. 

The sticky tape/powder problem can be temporarily relieved by baking the
tape for at least 8 hours at 55°C (130°F) and an extreme case may require
18-24 hours. A convection oven is recommended for this procedure. This
heating process makes the tape usable for a few weeks and can be repeated
many times. I recommend copying any tapes that develop this problem
because their long-term durability is questionable. The second problem,
binder degradation, can sometimes be reversed by storing the tapes in a
cold and dry environment for a couple of weeks. The third problem of tape
damage is usually caused by one edge of the tape being curled and is the
result of an improperly aligned tape transport. A severe case of edge
damage, pleating, or creasing is usually difficult to play, but I have
developed a method of correcting the problem so that the tape is at least
playable..." 

The rest of the article at the web site is interesting, and there is also
another good article at: 
http://palimpsest.stanford.edu/cpa/reports/sound.html

entitled "The Care and Handling of Recorded Sound Materials", by: 
Music Division / National Library Of Canada

I would caution that this drying method appears to be workable for
polyester, etc. based tape formulations from the 70's and 80's, but for
tapes made before the mid 60's, which use an acetate base, baking and
drying could cause severe tape breakage problems. Hope this helps! 


Pat Kirtley