Hi, Tom,
All the 206 that I own and have tried playing is fine, but some client
tapes have been stiffer. They have all played well with little or no
dusting.
Yes, I have noticed the stiffening more on Maxell UD-50 (1.5 mil) than
UD-35 (1 mil). I haven't really thought about whether it was the mag
coat or the base film. The tapes I bought in the 1970s were NOT the
backcoated variety.
I had assumed the stiffness was a degradation of the PET base film as I
didn't think (until you mentioned it) that the mag coat would have
enough structural strength to change the stiffness of the whole package,
but, upon further thought, perhaps it would...think of hairspray.
Cheers,
Richard
On 1/24/2016 8:10 AM, Tom Fine wrote:
> Richard, I think that "stiffness" you and I have seen is taken to the
> extreme in what Shai said he dealt with in 206/207 tapes. If I
> understand Shai correctly, his problem was the oxide flaking off, which
> would happen if the tape is so stiff that it's not able to travel
> through the path without the oxide surface cracking and flaking. I have
> not encountered that extreme, but often have to clean up small amounts
> of oxide dust when I transfer old 206 tapes, especially a particular set
> that I own that was stored in an attic for 10+ years. Do you think the
> binder actually dries out, making these tape stiff, or is it more likely
> a change in the polyester over time, or is that the same thing?
>
> I've also seen slight "stiffening" of Maxell UD and UDXL 1-mil tape over
> time, but it doesn't seem to cause any flaking or dust-dropping, and it
> doesn't seem to effect that tape's performance as far as sound quality
> and moving through various transports, at all.
>
> -- Tom Fine
>
> ----- Original Message ----- From: "Richard L. Hess"
> <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Saturday, January 23, 2016 4:27 PM
> Subject: Re: [ARSCLIST] One more sticky-shed data point - Richardson
> treated tape
>
>
>> Hi, David,
>>
>> I would suspect it was not a coincidence. How is 400 holding up?
>>
>> 206/207 is starting to get stiff in many instances, but is still
>> holding up in other ways. I think we've heard some reports of shedding
>> or possibly binder hydrolysis, but nothing major other than the
>> stiffness.
>>
>> Cheers,
>>
>> Richard
>>
>>
>>
>> On 1/23/2016 4:07 PM, David Crosthwait wrote:
>>> Coincidentally or not, 1969 was about the time that 3M Scotch
>>> introduced back-coated model # 400 color videotape. In addittion to
>>> the binder introduction, the base film was more elastic in nature,
>>> leading for some improvement in Quad-head life.
>>>
>>> Regards,
>>>
>>> David Crosthwait
>>> DC Video
>>>
>>> http://www.dcvideo.com/what-we-do
>>>
>>> [log in to unmask]
>>> http://dcvideo.com/
>>> Follow DC Video on Facebook: https://www.facebook.com/dcvideo
>>> Follow DC Video on YouTube: http://www.youtube.com/user/dcvideoonline
>>>
>>>
>>>
>>> On Jan 23, 2016, at 12:50 PM, Richard L. Hess wrote:
>>>
>>>> Hi, Peter,
>>>>
>>>> I apologize! I think now we are all in violent agreement here, then.
>>>> Thank you for a clear explanation and also thank you for noting that
>>>> the resulting polymers after baking are more likely to revert.
>>>>
>>>> I'm not trying to cause trouble, I'm trying to understand...still.
>>>>
>>>> Yes, the packing was a major consideration in the back coating
>>>> design...allowing a path for entrained air to escape.
>>>>
>>>> Wasn't 3M first with back coating with 206/207 in 1969 (3M date
>>>> confirmed via the late Del Eiler's spreadsheet at aes.org/aeshc/)?
>>>>
>>>> I think that was billed at the time as static drain, better escape
>>>> of entrained air, and better guidance, but I could be wrong. Anyone
>>>> have data sheets / ads going back to then?
>>>>
>>>> Thanks for sharing all this information.
>>>>
>>>> Cheers,
>>>>
>>>> Richard
>>>>
>>>>
>>>>
>>>> On 1/22/2016 8:48 PM, lists wrote:
>>>>> Arrgh, Richard:
>>>>>
>>>>> You did exactly what I asked "please" not to get into in my early
>>>>> post. Oh well- I said quite that hydrolysis is NOT REVERASBLE it
>>>>> is BI-DIRECTIONAL. People keep trying to prove the wrong thing- it
>>>>> is not reversible, it is not reversible, it is not reversible- it
>>>>> is bi-directional! The oligomers cross-link back into polymers. We
>>>>> and others have proven this in the lab- not just Cuddihy.
>>>>>
>>>>> They don't cross-link back into the original polymers (not
>>>>> reversible!). In addition, the polymers that are created by the
>>>>> cross-linking are almost always shorter than the originals- which
>>>>> means they are more subject to hydrolysis breakdown in the future
>>>>> than the originals-but they are still polymers and aren't "sticky".
>>>>>
>>>>> Sorry for the "rant".
>>>>>
>>>>> As for the carbon black, my contact at AMPEX who helped work on
>>>>> tape development indicated that the backcoating was not done as a
>>>>> static barrier but as a method to allow to tape to pack more smoothly.
>>>>>
>>>>> Peter
>>>>>
>>>>> -----Original Message-----
>>>>> From: Association for Recorded Sound Discussion List
>>>>> [mailto:[log in to unmask]] On Behalf Of Richard L. Hess
>>>>> Sent: Friday, January 22, 2016 1:29 PM
>>>>> To: [log in to unmask]
>>>>> Subject: Re: [ARSCLIST] One more sticky-shed data point -
>>>>> Richardson treated tape
>>>>>
>>>>> On 1/22/2016 12:05 PM, lists wrote:
>>>>>> Also,
>>>>>> remember, hydrolysis is a bi-directional chemical reaction. Not only
>>>>>> is there a threshold at which hydrolysis will occur, there is also a
>>>>>> threshold at which hydrolysis will run in the other direction and the
>>>>>> oligomers will cross-link back into polymers.
>>>>>
>>>>> Hi, Peter,
>>>>>
>>>>> That was definitely Bertram and Cuddihy's conjecture, but in the
>>>>> work that Ric Bradshaw did at IBM, he has seen evidence that this
>>>>> is not the case. As I understand it, he draws the following
>>>>> distinction:
>>>>>
>>>>> In basic chemical theory, the reaction is bidirectional, but in the
>>>>> filled matrix that is the recording tape binder, there is little
>>>>> likelihood that the ends of the severed long chain molecules will
>>>>> find receptive "landing sites" [RLH's phrase, not RWB's] and even
>>>>> less likelihood that they will find the original points from which
>>>>> they were severed.
>>>>>
>>>>> So, while there may be some random cross linking, the physical
>>>>> presence of the magnetic particles, lubricants, and other
>>>>> components of the mag coat matrix interferes with the reversing of
>>>>> the process. I believe I can state Bradshaw's conjecture as: yes,
>>>>> there may be some re-linking, but it never will come close to the
>>>>> original condition on day of manufacture. In other words, once it
>>>>> goes down this path, it's never coming all the way back.
>>>>>
>>>>> Thank you for the clarification of Richardson's hypothesis. I don't
>>>>> think I ever got that out of what I've read of his, but I have not
>>>>> read all of the material he sent as some was sent under
>>>>> non-disclosure and I do not recall opening it. I felt if I read it
>>>>> and integrated it into my understanding, I might inadvertently
>>>>> disclose something. At one point in my past life, I commented, "I
>>>>> have signed so many NDAs that I can't even talk to myself!"
>>>>>
>>>>> Also, thanks for confirming the existence of a threshold in the
>>>>> onset of hydrolysis. That makes sense.
>>>>>
>>>>> One other question. One of your recent posts seems to suggest that
>>>>> the hydrophilic nature of the carbon black or other back-coating
>>>>> materials was part of the plan. Was it? Or was carbon black chosen
>>>>> to be conductive to dissipate the static charge which, under
>>>>> certain conditions can spark over and print a "tick" to the tape?
>>>>> Perhaps the hydrophilic nature of carbon black was either ignored
>>>>> or not known by the designers--or they thought that it wouldn't be
>>>>> an issue. It would be much more expensive to deposit a copper or
>>>>> silver (and probably even
>>>>> aluminum) thin film on the back side of the base film to provide
>>>>> that conductivity.
>>>>>
>>>>> Thanks!
>>>>>
>>>>> Cheers,
>>>>>
>>>>> Richard
>>>>>
>>>> --
>>>> 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.
>>
>>
>
--
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.
|
