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ARSCLIST  January 2016

ARSCLIST January 2016

Subject:

Re: One more sticky-shed data point - Richardson treated tape

From:

David Crosthwait <[log in to unmask]>

Reply-To:

Association for Recorded Sound Discussion List <[log in to unmask]>

Date:

Tue, 26 Jan 2016 08:49:32 -0800

Content-Type:

text/plain

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text/plain (154 lines)

Hello Tom,

I think it's safe to say the following: Once we think we have figured it out, we are setting ourselves up for a disappointment.

I have always been of the opinion that unless we are dealing with our own personal tapes in recovery (where we can guarantee 100% it's legacy of storage conditions), the history of the media we have been handed is a great unknown, no matter what the client states ("Oh it's always been in a cool, dry environment").  We heard it all. With that in mind, we open each container (if their is one) and start the preparation process on a case by case basis. Even if it looks familiar, we don't know the following:

1)	Manufacturing run and it's composition i.e. backing/binder/oxide "soup" version.
2)	The environment the tape experienced during it's travel from the manufacturer to the end user (Example: Did it sit on the airport tarmac palletized for extended periods and if so, in hot, cold, direct sunlight, dry, moist?)
3)	What physical abuses, if any, was the tape stock subjected to during recording i.e. severe tension swings due to mal-aligned first or second generation VTR's? Multiple-pass editing? Was this in a cigar-smoke filled VTR room? Was this a remote in Manhattan where the back door of the VTR 			area is open, exposing the tape stock to possible mid-city air contaminants? Or was it at Manhattan Beach at the ocean's edge where salt-spray is just outside the Compact Video truck window (been there)?
4)	After production and airing, who had their hands on that tape and where? How was the tape handled, abused and under what environmental conditions?
5)	For it's 40+ year storage history, what were the the uses, abuses and the temperature/humidity swings? Outhouse? Underground salt vaults?
6)	The container (if any): Was the tape wrapped in some sort of plastic bag and if so, how long? The plastic container: Was it outgassing any undesired particles (remember, it may have been a tightly-sealed closed environment for a long time)? The fire-retardanet properties of a 1" B format tape 			container manufacturer has been flagged as an issue in tape stock contamination. If in a cardboard box, was the acidic nature (if any) contaminating the tape? 
7)	The anodized flange has been seen to deteriorate, spreading microscopic particles onto the tape pack.

In summary, one has to look at other issues surrounding archived tape storage when encountering playback issues. 

When the Challenger blew up, an intensive study with analysis followed immediately. The entire team at NASA and it's suppliers were involved. Unfortunately, we don't have that sort of power in our business.


Regards,

David Crosthwait
DC Video

http://www.dcvideo.com/what-we-do


On Jan 26, 2016, at 5:56 AM, Tom Fine wrote:

> Hi Richard:
> 
> For me, the key learning from Peter Brothers and you is that baking doesn't "put humpty-dumpty together again," i.e. return the tape to its exact pre-SSS condition. That would be an avenue toward explaining audio degradation and also might explain why we've gotten some reports of recent re-baking of tapes baked in previous years are taking longer. The return to SSS after baking might be more gooey and insidious. I do think more scientific study is called for, and I think Richardson's knowledge should be brought to the table, as I suggested through treating him as less of a pariah. I think ARSC is the obvious venue for all of this because of its membership and because I've seen collegial discussions among people of differing views in various ARSC venues.
> 
> I think it would be helpful to review these questions:
> 
> 1. do we really understand the mechanism of binder breakdown and stickiness? For all its permutations?
> 
> 2. can we quantify what sonic damage occurs from repeated baking? Or, can this be measurably ruled out?
> 
> 3. do we need new guidelines for baking times, given the age of the Ampex patent and the recent field experiences?
> 
> 4. what of Richardson's claims that baking is inherently damaging to the content of magnetic tapes? Can we encourage him to share data he's collected and expound further on his ideas? Can we get a detailed description of Richardson's back-coat removal process, and his ideas on making this scalable and widely practical?
> 
> 5. it's clear that there are a lot of ideas on tapes that don't respond to baking, but what is the science?
> 
> 6. does cold/dry storage appropriate for binder-problem tapes actually harm acetate tapes by drying them out? Or, does it stave off vinegar syndrome, perhaps at the cost of making acetate tapes very brittle? Would cold but less dry storage be more appropriate for acetate tapes?
> 
> 7. how does this apply to all-digital tapes? Can we quantify if baking damages digital information beyond the capacity of error-correction? Can we be sure that baking is the appropriate action for digital tapes that won't move smoothly through a transport?
> 
> I thank especially Peter and Richard for leading this most interesting discussion (and thank everyone else who has chimed in because all data points from the field are interesting), and I hope we continue to get deep in the weeds on this topic, because it is absolutely vital for anyone with analog magnetic tapes.
> 
> -- Tom Fine
> 
> ----- Original Message ----- From: "Richard L. Hess" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Tuesday, January 26, 2016 8:22 AM
> Subject: Re: [ARSCLIST] One more sticky-shed data point - Richardson treated tape
> 
> 
>> Hi, John,
>> 
>> I'm sorry, I said "deposition" to cover SSS tapes. Thanks for the clarification.
>> 
>> To further clarify, in my worldview--and I am only trying to use this taxonomy for the sake of clarification of failure modes and their treatment, Soft Binder Syndrome (SBS) is an over-arching condition and Sticky Shed Syndrome (SSS) is a subset with, at this point, nothing hanging outside the SBS representation in the Venn diagram.
>> 
>> While there may be degrading tapes which are not SBS, SSS tapes so far (with or without backcoat) are also SBS tapes. A degrading, non-SBS tape, for example, would be an acetate tape which is suffering from vinegar syndrome. It is also non-SSS.
>> 
>> To me, the definition of SSS is SBS that can be temporarily reversed through "baking" roughly following the rules of the Ampex patent, but allowing now for extended baking times.
>> 
>> The treatments that I have been discussing for almost the last decade (OY--has it really been that long--it was October 2006, that I presented the paper at the AES in San Francisco) such as D5, cold playback, and fast playback, are meant for tapes that normally do not respond to baking. I see these three methodologies overlapping to some extent within the SBS circle, but not overlapping with SSS, by definition.
>> 
>> It may be ultimately shown that those three treatments plus Marie O'Connell's isopropynol playback overlap to some extent, if not completely. I do not think that any of these four techniques overlap with SSS because none of them allow for the separation of the mag coat from the back coat when they are adhering firmly enough to pull off the mag coat. Those bonds seem to be broken during the baking.
>> 
>> This may be another validation of Peter Brothers' explanation that some repolymerization is occurring during the baking. I had always until now considered that the bonds between mag coat and back coat are broken during the baking cycle.
>> 
>> However, an alternate explanation of the process could be that the mag coat's internal bonds (to itself and to the base film on the proper side) are strengthened by the baking process to better allow the temporary bonds with the back coat to be broken with no ill effect. However, if that were the case, I would expect to still hear some "ripping" which I do not hear when winding a baked tape.
>> 
>> So that is why I have suggested that the baking process breaks the temporary bonds between mag coat and back coat that happen during the binder hydrolysis and related failure modes of SSS. I have carried on this bond-breaking-by-mechanical-means (thermal contraction and expansion) to include cold desiccation's partial success in un-pinning pinned, non-back-coated tapes that would suffer from mag coat pullout.
>> 
>> I realize we are putting a very fine point on all of this, but, ultimately, I think this increases our (at least my) understanding of the mechanism, variants, and cures for tape degradation modalities.
>> 
>> Cheers,
>> 
>> Richard
>> 
>> 
>> 
>> I realize that a symptom/cure-based taxonomy is less scientific than a cause-based taxonomy (binder hydrolysis, vinegar syndrome, etc), but it does have a practical application in the field for those of us struggling with tapes that are misbehaving. If they ain't misbehavin' then they don't get a classification other than, "tape" <smile>.
>> 
>> 
>> 
>> 
>> 
>> On 1/25/2016 9:27 PM, John Schroth wrote:
>>> Hi Richard:
>>> 
>>> To be clear these tapes I talk about did not have back-coating and
>>> exhibited classic signs of sticky-shed, They quickly left large binder
>>> deposits on the heads when tested and responded very well to baking.
>>> 
>>> These were not squealing tapes, what you have referred to in the past as
>>> soft binder - that needed cold play or Marie O'Connel's playback method.
>>> These were sticky shed tapes that did not have back-coating.
>>> 
>>> My point was that we cannot ALWAYS associate sticky shed with back-coating.
>>> 
>>> Kind Regards,
>>> 
>>> John Schroth
>>> MTS
>>> 
>>> On 1/24/2016 11:10 PM, Richard L. Hess wrote:
>>>> Hi, John,
>>>> 
>>>> This is indeed true. HOWEVER, my success rate for baking tapes that
>>>> are suffering from squealing and/or deposition that are not back
>>>> coated is much lower.
>>>> 
>>>> This raises another question. If all binder breakdown is hydrolysis,
>>>> then why doesn't baking cure it 100%? I'm thinking of Sony PR-150 and
>>>> 3M-175.
>>>> 
>>>> These two seem to show the falling Tg, but don't have the shedding.
>>>> They are outliers and inconsistent.
>>>> 
>>>> Cheers,
>>>> 
>>>> Richard
>>>> 
>>>> 
>>>> 
>>>> On 1/24/2016 3:41 PM, John Schroth wrote:
>>>>> Back-coating may instigate or speed up the hydrolysis process but I
>>>>> cannot ignore the fact that there are still obscure instances where the
>>>>> tape had no back-coating and suffered from SS. Richard, you have noted
>>>>> this in the past and I have had this happen in at least two instances
>>>>> that I can recall. I'm at home today so I don't have access to my notes,
>>>>> but it was clearly sticky shed on tapes that had no back-coating. So one
>>>>> should not "always" equate back-coating with sticky shed.
>>>>> 
>>>>> Just my two cents...
>>>>> 
>>>>> John Schroth
>>>>> MTS
>>>>> 
>>>> 
>>> 
>> -- 
>> Richard L. Hess                   email: [log in to unmask]
>> Aurora, Ontario, Canada                             647 479 2800
>> http://www.richardhess.com/tape/contact.htm
>> Quality tape transfers -- even from hard-to-play tapes.
>> 

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