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ARSCLIST  April 2013

ARSCLIST April 2013

Subject:

Re: remanence decay and tape aging

From:

"Richard L. Hess" <[log in to unmask]>

Reply-To:

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

Date:

Wed, 17 Apr 2013 20:49:04 -0400

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (210 lines)

On 2013-04-17 4:47 PM, Tom Fine wrote:
> Hi Richard:
>
> In your point (d), are you agreeing with my theory that sticky-shed 
> tapes will go sticky no matter how they are stored? 

Yes, but the meeting I had this summer at LoC seemed to indicate that 
the baking times are not rising nearly as fast from their cold storage 
as the samples I see "in the wild. So I still think cold storage is a 
plus at least until you have a great digital copy.

> Also, do you think they go back to being sticky after being baked, now 
> matter how they are stored? 

I think so, but again, it will be slower.

> I think yes to both questions, based on experience, which is why I 
> think it's foolish to go to the expense of a super-low-humidity 
> storage environment in an effort to "remedy" sticky-shed. 

The point is if you don't have the capacity to transfer it now, you need 
to protect it as best you can until you do transfer it. It's like the 
Corbus collection--they figured out if they didn't FREEZE it, there 
would be lost images before it could all be scanned.

> And, if that's not the reason for super-dry, then what else, 
> especially since it seems (again from personal experience) to ruin 
> acetate-backed tapes.

Segregation seems like a good idea in this instance (please do not 
misquote me and apply this to larger topics).

>
> Regarding John Haley's post, my northeastern US indoor environment 
> varies from about 50% humidity in the winter (it can go lower on days 
> where it's bone-dry outside and the hot water heating system is on 
> full bore) to about 60% in the summer (some days requiring the 
> dehumidifier because the concreate slab "sweats" if it's hot and humid 
> enough). That doesn't seem like a massive variance that would ruin 
> magnetic media quickly. Ideally, if I wanted to spring for a robust 
> climate-control system, I'd probably opt for around 55% humidity and 
> 65 degrees all the time. That seems to be the most comfortable indoor 
> working environment and equipment seems to like it best. It also seems 
> to be good for keeping static charges under control.
I've been running 40-50% this winter. In our climate, too wet can damage 
the house. 50% is sort of the upper limit for winter or you might end up 
with mould and rot in the house.

Cheers,

Richard
>
> -- Tom Fine
>
> ----- Original Message ----- From: "Richard L. Hess" 
> <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Wednesday, April 17, 2013 4:29 PM
> Subject: Re: [ARSCLIST] remanence decay and tape aging
>
>
>> Shai,
>>
>> Jay "MRL" McKnight actually has a paper looking at what might be a 
>> "safe" field.
>> http://home.comcast.net/~mrltapes/field-strength-for-partial-erasure.pdf
>> (I don't see it currently indexed on his HTML, but Google found it)
>> and the IASA has a report and I'll leave the exercise to the student 
>> converting units
>> between Jay's paper and the IASA report.
>> http://www.iasa-web.org/magnetic-fields/influence-recorded-tape
>>
>> John,
>>
>> Thanks for the kind words about my paper and website. I have a 
>> slightly different mental model of what you're describing:
>> (a) Temperature and humidity and especially the cycling thereof is 
>> not good for tapes.
>> (b) Tom Fine postulates (and I tend to take this seriously) that 
>> too-low humidity such as that recommended for storing tapes subject 
>> to SSS is very bad for acetate tapes.
>> (c) The binders that are extremely subject to degradation based on 
>> normal room temperature heat/humidity were improper 
>> applications/designs or poorly/incompletely reacted during manufacture.
>> (d) While storage conditions play a role, there are tapes with 
>> inherent vice that will self-degrade far more rapidly than other 
>> tapes. This "vice" was built-in during the design/manufacture process.
>> (e) Tape type numbers are only a loose approximation for identifying 
>> tape chemistries
>> (f) Lot-to-lot variations can be VERY substantial even within the 
>> same chemistry.
>>
>> Cheers,
>>
>> Richard
>>
>> On 2013-04-17 3:42 PM, John Haley wrote:
>>> I just read your 2008 tape article from ARSC Journal, Richard, and 
>>> looked
>>> at your website, thanks very much for sharing all this valuable info 
>>> you
>>> have collected about the vicissitudes of various tapes.   I have not 
>>> seen
>>> this much good collected empirical info anywhere else.  You're the man!
>>>
>>> I have always assumed that in addition to things that happen 
>>> resulting from
>>> manufacture, tapes are highly affected by things like heat and humidity
>>> during the years that they have been stored.  A household in the 
>>> Northeast
>>> that does not run a humidifier in the winter can get far dryer than the
>>> Sahara desert, to the detriment of everything in the house--furniture,
>>> wood, living things and things made from chemicals, like tapes.
>>>
>>> Thanks,
>>> John Haley
>>>
>>>
>>> On Wed, Apr 17, 2013 at 3:06 PM, Shai Drori <[log in to unmask]> 
>>> wrote:
>>>
>>>> Jay I assume from MRL? If so, he has a little leaf he hands out 
>>>> with every
>>>> test tape he sells, that is a very interesting read. In short, he 
>>>> claims
>>>> (and I believe it) that the tapes are very robust and that if you read
>>>> through his description you realize that it takes a very strong 
>>>> magnetic
>>>> field to erase a tape.
>>>> Shai
>>>> בתאריך 17/04/13 7:01 PM, ציטוט Richard L. Hess:
>>>>
>>>>   Hello, Gregorio,
>>>>> In general, the magnetic record seems to be rather robust and it 
>>>>> mostly
>>>>> decays from close encounters with magnetic fields stronger than the
>>>>> Earth's. I know of no studies that have attempted to quantify 
>>>>> this, but I'm
>>>>> copying Jay McKnight who may know of a study and if he has any 
>>>>> information,
>>>>> I'll post it to the list.
>>>>>
>>>>> So, assuming no chemical or physical degradation (which mostly affect
>>>>> tape via spacing loss across part or all of the tape) and no close
>>>>> encounters of the strong magnetic kind, the S/N decay rate would 
>>>>> be minimal
>>>>> (I don't want to say zero, but I suspect close to it).
>>>>>
>>>>> We had the discussion on the Studer list about whether tape or 
>>>>> machine
>>>>> background noise is predominant and Jay chimed in with an "it 
>>>>> depends". For
>>>>> master tapes, generally the tape noise is predominant. There are 
>>>>> times at
>>>>> slower speeds and narrower tracks where head/electronics noise 
>>>>> would be
>>>>> predominant.
>>>>>
>>>>> As to degradation factors, I have a page I try and keep updated where
>>>>> this is discussed.
>>>>>
>>>>> http://richardhess.com/notes/**formats/magnetic-media/**
>>>>> magnetic-tapes/analog-audio/**degrading-tapes/<http://richardhess.com/notes/formats/magnetic-media/magnetic-tapes/analog-audio/degrading-tapes/> 
>>>>>
>>>>>
>>>>> I hope this helps a bit.
>>>>>
>>>>> Cheers,
>>>>>
>>>>> Richard
>>>>>
>>>>>
>>>>> On 2013-04-17 12:32 PM, Gregorio Garcia Karman wrote:
>>>>>
>>>>>> Dear members,
>>>>>>
>>>>>> I am looking for references in the literature dealing with the 
>>>>>> study of
>>>>>> the decay of magnetic remanence as an effect of tape aging. What 
>>>>>> is the
>>>>>> expected signal-to-noise decay rate under ideal conditions (i.e. no
>>>>>> chemical degradation)? In real life, what is your experience in 
>>>>>> regard to
>>>>>> different brands / models in similar storage conditions?
>>>>>>
>>>>>> Thanks in advance and regards
>>>>>>
>>>>>> Gregorio
>>>>>>
>>>>>
>>>> -- 
>>>> בברכה,
>>>> שי דרורי
>>>> מומחה לשימור והמרה של אודיו וידאו וסרטים 8-35 ממ.
>>>>
>>
>> -- 
>> 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.
>>
>

-- 
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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