I think Dennis is bringing up a really important point. Sarah and Richard, do you have any contacts 
with original tape manufacturer chemists, people who were familiar with the "brew" of the tapes? 
Before these people die, it's important to get information from them about what chemicals were used 
in the binders. There's no "state secret" anymore -- all of those tape manufacturers are out of 
business now (and I'm afraid, given how things work, that corporate records detailing the "brew" are 
probably lost to time). One rumor that's widely circulated is that sticky-shed stems from American 
manufacturers losing access to whale oil, so something else had to be used in the binder and 
unintended consequences ensued. I've also seen this rumor denied by former 3M employees, but I don't 
think those people were actual tape-brew chemists. It would be helpful to know these facts.

On a related line of inquiry, there should be research about storage of non-sticky tapes. My own 
first-hand experience with acetate and early polyester tapes is that if you store them in too dry an 
environment, the edges curl and the acetate tapes become very brittle. I can state first-hand that 
you can improve playback on an acetate tape that isn't vinegar-syndrome but is edge-curled by 
b-winding it (oxide out) and letting it sit in a cool, somewhat humid but not wet environment for a 
few months, then returning it to a-wind and playing it. I've had good luck with this method with 
quarter-track acetate tapes, often able to make the left channel mostly playable without extreme 
measures like putting gauze in the play-head can. All of this backs up my theory that the very-dry 
storage conditions recommended for sticky-era tapes are not appropriate for older tapes and hasten 
the complete disintegration of acetate tapes because they dry out and become so brittle that the 
oxide flakes off. As I've said before, I haven't seen any science saying that super-dry storage 
conditions has any effect on sticky-shed, the tapes still need baking and still go back to sticky 
after they've been baked. So why ruin other tapes in an ineffective attempt to "preserve" sticky 
tapes?

-- Tom Fine

----- Original Message ----- 
From: "Dennis Rooney" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, April 05, 2013 1:01 PM
Subject: Re: [ARSCLIST] Sticky SHRED


> Unless I have overlooked an important post on this topic or am
> misunderstanding something, what I find missing in this discussion is
> any comment on the number of different oxide formulations by both age
> and manufacturer that have been investigated with respect to binder
> hydrolysis. We know from experience that the phenomenon affects
> preponderantly those tape types manufactured after 1975, Earlier
> formulations exhibited other problems but were stable with respect to
> binder hydrolysis. If my surmise is correct, there is much further
> study to be carried out on the problem in order to discover
> preservation and playback strategies that are more than anecdotal..
>
> DDR
>
> On Thu, Apr 4, 2013 at 4:40 PM, Sarah Norris <[log in to unmask]> wrote:
>> Hi, Tom (and list):
>>
>> Please find responses below:
>>
>>>Would you, for us non-scientists on the list, summarize Bradshaw's
>> thinking and the opposing view(s)?  Please try to keep it in the realm
>> of what an English major or at least what a MLS major can comprehend.
>>
>> A more thorough description is in my post from April 2, but here's a
>> very abbreviated summary:
>>
>> Bertram / Cuddihy's model says baking works because it repairs the glue
>> that holds the media together.
>>
>> Bradshaw / Bhushan's model says baking works because it makes the media
>> and other degraded fragments hold hands for awhile.
>>
>>>Do any of the theories you explored about what causes sticky-shed
>> reveal why baking times would be increasing as the tapes get older?
>>
>> The models summarized above answer the question, "Why does baking work?"
>> The question we're asking now is something closer to, "How are tapes
>> aging?"  I think the first question probably is relevant to the second
>> question, but probably not in a direct, straight-line kind of way.  It
>> makes logical sense that longer required baking times indicate more
>> advanced degradation.  Is that really the case?  Now might be a great
>> time for a series of studies, one every few years, comparing required
>> baking times with degraded binder in tape samples!
>>
>>
>> Sarah Norris
>> Conservator
>> Texas State Library and Archives Commission
>> phone: (512) 463-5446
>> fax: (512) 463-5430
>> e-mail: [log in to unmask]
>
>
>
> -- 
> 1006 Langer Way
> Delray Beach, FL 33483
> 212.874.9626
>