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ARSCLIST  January 2016

ARSCLIST January 2016

Subject:

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

From:

Tom Fine <[log in to unmask]>

Reply-To:

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

Date:

Tue, 26 Jan 2016 08:56:11 -0500

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text/plain

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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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