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ARSCLIST  April 2013

ARSCLIST April 2013

Subject:

Re: tape chemistry/processing

From:

[log in to unmask]

Reply-To:

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

Date:

Sat, 6 Apr 2013 08:05:04 -0400

Content-Type:

text/plain

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text/plain (255 lines)

I bought some of that reslit tape, extra long lengths on a 7 in reel.  
Worked fine.
 
Don Chichester
 
 
In a message dated 4/6/2013 12:43:55 A.M. Eastern Daylight Time,  
[log in to unmask] writes:

At DAK  we got our binder and dry oxide from MagNox, these were mixed in a 
drum mixer  along with MEK as a thinning agent that also improved adhesion 
to the base  polyester (aka dupont mylar) film.
Mag tape coating is similar to the first  step in Offset printing. The 
oxide (ink) is supplied to a roller and passes  through a metering blade that 
leaves a smooth thin layer of oxide on the  roller that rotates against the 
film base and transfers the oxide  coating.  
Traveling through an oven evaporates the solvent and begins  to harden the 
coating, which next passes through calendar rollers which  smooths and 
compresses the oxide coating under pressure and heat to finish  hardening the 
coating.  
Two types of calendar rollers were used with  different tape surface 
textures. A Nylon roller would leave a soft matte  finish while a hard chrome 
roller would give the oxide a highly polished sheen  which looked nice but  
would cause increased odixe to tape head adhesion  because of the lack of 
microscopic air pockets in the oxide..... often to the  point of squealing noise.
The highly polished hard chrome surface was  mostly used for video and high 
speed instrumentation tape.
At DAK we coated  on 6-8-12" web widths. Rotary slitters converted the webs 
to 1/8" cassette and  1/4" reel stock into master pancakes. 
One step that could contribute to  oxide flaking is the calendaring 
processing where pressure and heat are  critical to long term adhesion.
The hard chrome finished surface of the  oxide can contribute to head/tape 
squeal due to surface adhesion. The hard  chrome finish at one time was 
promoted as providing few drop outs and more  uniform output in Master tape 
products when used at higher  tape  speeds....  where did the seconds end up ?  
you guessed in the  bargain boxed 3M and Ampex, which accounts for the 
inconsistency of the  bargain box stock. 
Also the Melody brand used reslit 1/2" computer stock  that was returned to 
the mfgr for credit toward new stock... it was part of a  gov buy back 
program...  again  nothing goes to waste, find a way to  reuse it.
Even DAK  secured 1000's of reels of computer and  instrumentation tape to 
be reslit.

d nelson ward 


Beautiful  Music you will never forget, at;  
http://www.americanbeautiful.podbean.com/




--- On Fri,  4/5/13, Richard L. Hess <[log in to unmask]> wrote:

>  From: Richard L. Hess <[log in to unmask]>
> Subject: Re:  [ARSCLIST] Sticky SHRED/tape chemistry
> To:  [log in to unmask]
> Date: Friday, April 5, 2013, 4:44 PM
>  My understanding was that BF Goodrich
> Estane was used widely as the  binder.
> 
> Dr. Bob Perry would not share any Ampex secrets with  me and
> said at the 
> time they were still secrets in his  mind.
> 
> PDF page 6 of my paper discusses this a bit more  formally
> than my 
> previous post.
> 
> This would  be useful information...
> 
> Let's all rattle whatever cages we  can.
> 
> Cheers,
> 
> Richard
> 
> On  2013-04-05 6:56 PM, Dan Nelson wrote:
> > Back in the 80s i was  working for DAK industries and we
> were coating our own webs and  slitting 1/8" and 1/4" stock.
> Before that i was familiar  with  Northridge magnetics
> who was making mastering quality 1/2"  tape.
> > In fact i set DAK up to buy the Northridge  facility.
> > MagNox was a prime supplier of  odixe and  coating
> chemistry to the  industry as a whole.
> > IM  looking for my folder of spec sheets which i thought
> i may have kept  when the Air Quality Inspections in LA 
> made it impossible to use  the  quantity solvents needed
> and DAK shut down the coating  plant.
> > Our next step was buying raw stock from Ampex here  on
> the West coast.
> > So any problems Ampex had in the 80s  was passed onto
> DAK labeled products.
> >
> > d  nelson ward
> >
> > Beautiful Music you will never forget,  at; 
http://www.americanbeautiful.podbean.com/
> >
>  >
> >
> >
> > --- On Fri, 4/5/13, Tom Fine  <[log in to unmask]>
> wrote:
> >
>  >> From: Tom Fine <[log in to unmask]>
> >>  Subject: Re: [ARSCLIST] Sticky SHRED
> >> To:  [log in to unmask]
> >> Date: Friday, April 5, 2013, 3:23  PM
> >> Richard, do any of these researchers
> >> know  the actual "recipes" for the tapes they are
> studying?
> >>  If not, is it possible to get that knowledge? Has
> anyone
>  >> interviewed in detail the tape manufacturers'
> chemists?  It
> >> sounds to me like we have a bunch of stabs in the
>  dark and
> >> theories. Are first-person details of actual
>  recipes already
> >> non-attainable?
> >>
>  >> Also, I would think a modern manufacturer like Mike
> Spitz  or
> >> Zonal could shed some light, perhaps talking about
>  other
> >> companies recipes rather than their own?
>  >>
> >> I really think it's time to get down in the  weeds
> with the
> >> chemistry, I can't see why the whole  process of
> sticky-shed
> >> is not understandable,  quantifiable and
> measurable???
> >>
> >> --  Tom Fine
> >>
> >> ----- Original Message ----- From:  "Richard L.
> Hess" <[log in to unmask]>
> >>  To: <[log in to unmask]>
> >> Sent: Friday, April 05,  2013 6:02 PM
> >> Subject: Re: [ARSCLIST] Sticky SHRED
>  >>
> >>
> >>> Hi, Nigel,
>  >>>
> >>> Thank you for this very useful insight!  This
> has been
> >> part of the mantra for a long time, but  it is
> wonderful to
> >> receive further  confirmation.
> >>> We cannot forget the "running changes"  that
> Benoit
> >> Thiebaut discovered specifically in  U-Matic tapes,
> but I
> >> suspect that process  "improvements" were common as
> tapes
> >> were running and  if this 60-70 % factor is involved
> it
> >> doesn't even  have to be a process improvement.
> >>> Cheers,
>  >>>
> >>> Richard
> >>>
>  >>> On 2013-04-05 4:53 PM, Nigel Champion wrote:
>  >>>> At last year's IASA conference in New
> Delhi,
>  >> Dietrich Schueller presented information gleaned
> from
>  >> discussions with retired employees of the major
> German  tape
> >> manufacturers, BASF & AGFA. Some expressed  the
> opinion
> >> that subtleties in the manufacturing  procedures had
> more
> >> influence on the finished quality  of magnetic tape
> than the
> >> actual chemical mix by a  factor of 60% or 70%.
> >>>> I infer from this that, even if  one tape
> has
> >> exactly the same chemical constituents  as another,
> a small
> >> variation in one step of the  manufacturing
> processes can
> >> result in pronounced  differences in measures of
> quality such
> >> as  performance, stability and/or longevity. 
> Such a
> >>  situation makes comparisons very difficult at this
> late
>  >> stage for those considering chemical analysis of
> >>  constituents or assessing differing degradation
> under
> >>  controlled climatic conditions as suggested
> recently on this
>  >> list for sticky-shed.  It would also explain
> the
>  >> differing experiences of many on this list with the
>  "same"
> >> tape.
> >>>> Nigel
>  >>>>
> >>>>  ________________________________________
> >>>> From:  Association for Recorded Sound
> Discussion
> >> List  [[log in to unmask]]
> >> on behalf of Tom Fine  [[log in to unmask]]
> >>>> Sent: 06 April 2013  07:23
> >>>> To: [log in to unmask]
>  >>>> Subject: Re: [ARSCLIST] Sticky SHRED
>  >>>>
> >>>> I think Dennis is bringing up a  really
> important
> >> point. Sarah and Richard, do you  have any contacts
> >>>> with original tape manufacturer  chemists,
> people
> >> who were familiar with the "brew" of  the tapes?
> >>>> Before these people die, it's important  to
> get
> >> information from them about what chemicals  were
> used
> >>>> in the binders. There's no "state  secret"
> anymore
> >> -- all of those tape manufacturers  are out of
> >>>> business now (and I'm afraid, given  how
> things
> >> work, that corporate records detailing the  "brew"
> are
> >>>> probably lost to time).
>  >>>> <SNIP>
> >>>>
>  >>>> -- Tom Fine
> >>>>
> >>> --  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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