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ARSCLIST  December 2010

ARSCLIST December 2010

Subject:

Re: SSS and other failure modes (was if you want it done right, do it yourself .../ not always)

From:

"[log in to unmask]" <[log in to unmask]>

Reply-To:

[log in to unmask]

Date:

Wed, 22 Dec 2010 17:41:33 -0600

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text/plain

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My one effort at transferring a reel of PR-150 was successful, thanks to 
you and all who pointed me in the direction of putting the tape in the 
fridge.

joe salerno


On 12/22/2010 4:39 PM, Richard L. Hess wrote:
> Hi, Shai and Michael (and Michael from off-list),
>
> I am here wrapping Christmas presents for my family...and figuring how
> to deal with 17 microphones (9 wireless) for the church Christmas
> Pageant Friday afternoon at the 3 and 5 PM services.
>
> Anyway, this is a complex issue and is addressed to some degree in my
> paper from the ARSC Journal.
>
> My paper on tape degradation that was originally presented at the Audio
> Engineering Society's 121st convention in October 2006 in San Francisco
> was published in the ARSC Journal in the Fall of 2008. It is available
> here:
> http://www.richardhess.com/tape/history/HESS_Tape_Degradation_ARSC_Journal_39-2.pdf
>
>
> However, this discussion is equating SSS with back coating.
>
> What I think I know is:
>
> (a) Almost all SSS tapes also have back coating.
> (b) Not all back-coated tapes exhibit SSS.
> (c) Charlie Richardson claims that removing the back coating will
> restore the tapes. He can discuss his findings in greater detail. I
> can't speak for him or his patented process which I have never tried to
> replicate.
> (d) The chemistries of the mag coat and the back coat may be similar or
> different, depending on the tape.
> (e) The precise chemical makeup of the tapes is unknowable at this point.
> (f) The degradation trajectory relating to basic chemistry,
> out-of-control processes (i.e. out of spec tape) and storage conditions
> is impossible to know at this point.
> (g) It appears that at least some manufacturers of some tape types
> substantially changed the tape chemistries while maintaining the same
> "model number". This is best documented by Benoit Thiebaut in his
> testing of video cassettes for Presto Space.
> (h) We think that polyester polyurethane binders were introduced about
> the same time back coating was introduced, so there may be no
> cause-and-effect relationship.
> (i) Some archives (I believe Screensound Australia) interleaves paper
> leader with back-coated tapes so that the back coat and mag coat are not
> in direct contact.
> (j) While the analogy may fail, have you ever seen an electrostatic copy
> (like a Xerox) that has spent a long time in direct contact with a vinyl
> binder? It's enough to make one wonder, at least.
> (k) Some polyester-polyurethane compounds do a good job of breaking down
> when exposed to moisture, especially at elevated temperatures.
> (l) Bradshaw did enough work to disprove that the chains re-link when
> baking as it just doesn't happen in a filled matrix.
>
> So, that's off the top of my head in five minutes...there is no simple
> answer and I doubt we'll ever have something as easy to use as a "pool
> test kit" for determining the likelihood of future SSS failure. If it
> says Ampex 406/407/456 on the box/reel and there is no reason to
> disbelieve it, bake before winding.
>
> I was also asked off-list about the composition of the back coat and I
> suggest the answer is really (e), above. Yes, carbon black is in many of
> the back coats to drain off static, but the "bad actor" here is not the
> carbon black but rather the binder chemistry. Also, I've never seen a
> back-coated audio CASSETTE tape. Has anyone?
>
> I have some SM911 that is going bad--I'm not certain it's SSS or just
> shedding. I forget if it's BASF or EMTEC.
>
> Here is a list of degrading tapes that I _attempt_ to keep current.
> http://richardhess.com/notes/formats/magnetic-media/magnetic-tapes/analog-audio/degrading-tapes/
>
>
> I've been asked to do work on some Sony PR-150--pray for me.
>
> Cheers,
>
> Richard
>
> On 2010-12-22 2:13 PM, Shai Drori wrote:
>> It's a good argument, but has it been tested. Has anyone tried to
>> store a back coated tape without it's back coating to see the
>> difference? If I remember correctly (where is Rich Hess when you need
>> him) the SSS was first discovered in ampex 400 series, but it was the
>> new binder they used. I don't see how that is affected by the back
>> coating, and why doesn't it affect all back coated tapes. I have many
>> different tapes with back coating, some of them almost 30 years old by
>> now that play like the day I bought them. Maxell XLI, BASF pem468,
>> BASF dpr26, emtec 911 (not 30 years old). To put the blame on the back
>> coating just because if is from the same era. It should have sown up
>> in all back coated tapes. What am I missing?
>> Shai
>>
>> On 12/22/2010 8:47 PM, Michael Biel wrote:
>>> On 12/22/2010 2:27 AM, Shai Drori wrote:
>>>> I have many tape that are back coated that show no SSS. In my
>>>> experience there is no connection whatsoever.
>>>> Shai
>>>>
>>>
>>> But how often have you found non-backcoated tapes with SSS?
>>>
>>> Mike Biel [log in to unmask]
>>>
>>>
>>>> On 12/22/2010 8:46 AM, Michael Biel wrote:
>>>>> The one saving grace of 8mm is that I don't think I have come
>>>>> across a backcoated tape in this format. So if there is any truth
>>>>> to SSS being a reaction to backcoating, that reduces that problem.
>>>>>
>>>>> Mike Biel [log in to unmask]
>>>
>>
>

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