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Re: [ARSCLIST] MAGNA-REEL Sound Recording Tape
At 04:16 PM 9/19/2006, Dave Nolan wrote:
>Is there a strong smell of vinegar or "lemon chicken" with these tapes?
Yes. The squealing tapes definitely have that "lemon chicken" smell.
OK, then the tapes are far more than dehydrated, and rehydration
generally won't help. Please look at the Image Permanence Institute
books on Vinegar Syndrome and your tapes have it just like the old
Tonschrieber tapes I did earlier this year.
http://www.imagepermanenceinstitute.org/shtml_sub/acetguid.pdf
http://www.ebu.ch/CMSimages/en/tec_text_r74-2001_tcm6-4685.pdf
http://www.imagepermanenceinstitute.org/shtml_sub/actionplan.pdf
Is there a recommended length of time in the fridge that anyone on the list
has used successfully? Any other "tape-in-the-fridge" handling tips? Any
suggested ways to measure whether the tape has hit 4 degrees celsius?
I would leave the machine in 8-12 hours and the tapes 4 hours for
1/4" tapes to be sure. It will take a much longer time for the tapes
to come to moisture equilibrium.
Yes, use a frost-free fridge (it will be dry) and keep the door shut!
Run the wires out thru the bottom of the door gasket.
Is rehydration still acceptable for non-squealing acetate tapes that
exhibit signs of cupping, excessive brittleness, etc...? I haven't gotten
to those yet, but will soon...
The more I think of it, the more I think it is a route of last
resort. I did it with one reel of carbonyl iron Magnetophonband from
1935 but it did not display any vinegar symptoms. The tape that had
hidden behind a woodstove during one or more New England winters did
NOT like hydration. It probably weaked the tape.
Is there any longitudinal spring to your acetate tapes? If so, that
is, I think, a sign of severe VS degradation. I found the cupping
could be flattened a bit by keeping the reels wound under tension for
a few days.
Oh the joys of 30 in/s full-track. I can't imagine what some of the
Magnetophonband tapes would have sounded like at 7.5 in/s quarter
track. Track 1 would have been gone, I fear. At 30 in/s FT, they sounded good.
>The other option is to reduce tensions and do a Pellon wipe (or
>several) as that has worked on 3M 175 (again a later tape).
While we're on the Pellon subject -
A) Is there a specific type of Pellon that is recommended for this sort of
use? I was very surprised to see the many many types and finishes of
Pellon out there - smooth, furry, thin, thick, etc... And of course, any
Pellon-handling tips and tricks would be greatly appreciated. I recently
saw an engineer using a 2" square between his fingers to clean the surface
while library-winding a tape. Other folks have suggested creating a Pellon
pad that entirely covers the stationary parts of the head block and either
playing back in "real-time" or library winding. What methods do folks here
like and why?
This is the stuff I use:
http://www.shoppellon.com/ProductDetails.aspx?productID=458
I use a strip wound around a pencil and I wrap the tape over that and
slowly unwind exposing new surface to the tape. I use library wind.
BUT, I've found that library wind is not great for tapes prone to
pullouts or pinning. So I use 1.88 in/s for that and am hoping to
build up an automated Pellon dispenser.
>The squeal MUST be attended to during playback as it is a stick-slip
>condition and will print to the digital file (as you discovered). So
>you don't even need to test with audio. If you can hear the squeal,
>try something else.
There is one technique I have heard discussed where one can theoretically
rig up the reel-to-reel machine to have the tape touch NO stationary parts,
but to have the tape pass close enough to the playback head for the signal
to be properly transferred. Is this reality or science-fiction?
No stationary parts other than the play head. 350 nm of spacing will
cause a 3 dB loss at 15 kHz at 3.75 in/s. Be advised. 350 nm is small.
>One other thing to consider about lubricant. It's there based on the
>design friction load. As the Tg drops, the tape gets more rubbery and
>the real tape contact area increases. Normal tape has a contact area
>in the neighbourhood of a few percent (2-3%) of the entire surface
>area, and the normal lubricant loads are designed for this with some
>margin. If by softening the surface, the contact area goes up, there
>isn't enough lubricant. This is why Marie O'Connell's wet playing
>works, but I'm not sure I'd want to try that with acetate as acetate
>is far more hygroscopic than PET (which is, surprisingly somewhat
>hygroscopic).
I have been in touch with Marie - as well as some other folks here in NYC
that are successfully using an isopropyl system to play back LOL tapes. My
only question is: Has anyone had any long-term deliterious effects from
the isopropyl on the tape? I'm not a scientist, nor do I pretend to be
one - but based on my limited use of isoprpyl to clean built-up oxide off
of tape heads, I'm wondering what effect (if any) on tape from using the
alcohol method might have been observed by list members...
Marie's process does NOT seem to damage the tapes, but she has used
it on PET basefilm (and perhaps PVC base film) tapes. The stuff dries
rapidly. In fact, one hypothesis as to why it works is that it cools
the tape surface and hardens it a bit. Think about that! A double
wammy - a lubricating film and a reduction in the oxide temperature.
It also conducts the heat of friction away from the head/tape
interface (which on a micro level is non-trivial according to
Bhushan's "Tribology and Mechanics of Magnetic Storage Devices, 2nd Ed."
>I hope shortly after AES to be set up to do cold playing easily, but
>I'm swamped at the moment. I really would like to know your results.
I'll certainly give everyone's suggestions a try here - and thanks again to
Richard in particular for the in-depth response...
You're welcome--this is new stuff that I'm previewing here and will
be presenting at AES in an 11,000 word paper.
But your tapes are classic vinegar syndrome IMHO and the best info on
that comes from the film world and IPI. Not pretty. Also, PLEASE
segregate any VS tapes from those that don't have it yet. It is
"contagious" in the sense that the off-gassing vapors from a
degrading tape can help catalyze a tape that wouldn't have gone VS
quite so soon.
Cheers,
Richard
Richard L. Hess email: richard@xxxxxxxxxxxxxxx
Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX
Detailed contact information: http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.