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ARSCLIST  January 2016

ARSCLIST January 2016

Subject:

Re: playback of disintegrating open reel tape

From:

Tom Fine <[log in to unmask]>

Reply-To:

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

Date:

Sat, 30 Jan 2016 08:18:03 -0500

Content-Type:

text/plain

Parts/Attachments:

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text/plain (168 lines)

Hi Eric:

I have not heard of the camphor treatment, but perhaps that's behind what Nadja is doing? I do think 
you should make sure to find and absorb the SMPTE journal articles about acetate, because Hollywood 
has already done research and come up with restoration methods.

Two questions for you, I hope you don't mind:

1. Isn't some derivative of TDK still in existence? If so, have you reached out to them? It's 
possible that there are records in Japan that could clear up the question of the tape base material.

2. Could you share your tape-humidification technique?

Oh, one more suggestion. If tape humidification works, make the material less brittle, I suggest you 
carefully reverse-wind it onto another reel (ie oxide side out), so the curl is in the opposite 
direction, and leave it on a shelf for a few weeks or longer. Then it will probably require 
humidification again before (careful) winding back onto its original reel with the oxide side down, 
and then try playback. In my experience, the reverse-winding usually helps the curl, but it takes 
some time and it's imperfect. The less brittle the material, the more likely it is to help. Assuming 
this tape is either a full-track or 2-track/half-track format, you may get your best results by 
playing it with a 4-track machine and using the middle two tracks to extract the audio, thus 
avoiding at least some of the warpage dropouts worst at the edge.

-- Tom Fine

----- Original Message ----- 
From: "Eric Jacobs" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, January 29, 2016 10:15 PM
Subject: Re: [ARSCLIST] playback of disintegrating open reel tape


Hi Tom,

I cannot identify the tape base. It doesn’t pass light through the side of
the reel - the reels are absolutely opaque.  But they also appear to be
0.5 mil - which doesn’t always pass light when viewed through the side of
the tape pack.

Detailed tape info:

    TDK-E (TDK Electronics)
    Synchrotape
    Type 12A-PL-8


Only one of the reels was stored in a sealed plastic bag.  It was
mechanically the strongest and most flexible in the collection (the entire
collection is on TDK Synchrotape).  It was the only tape that could be
leadered and played.  The strongest sign that the tapes may be acetate is
that only this one tape had a distinct vinegar smell when the plastic bag
was opened.

We regularly humidify tapes on acetate base.  That’s my next step.  We’ve
had good success with this in general, but these tapes are the worst we’ve
seen yet - the outer wraps are fused and the shrinkage is fairly extreme
as well.

I’m hoping these tapes are indeed double- or triple-play acetate, and that
the humidification succeeds.

Tom, you mention cellulose acetate film.  Do you know if anyone has used
camphor (plasticizer used with cellulose nitrate film) to revive acetate
audio tape?

~ Eric


On 1/29/16, 4:28 PM, "Association for Recorded Sound Discussion List on
behalf of Tom Fine" <[log in to unmask] on behalf of
[log in to unmask]> wrote:

>Hi Eric:
>
>Is this acetate-backed tape for sure? The description makes it sound that
>way. If it is, I recommend
>you try humidifying it for a while, let it get thoroughly humidified, and
>then play it in a
>relatively warm environment. All of that might make it less brittle, and
>also it might curl less as
>it goes through the guides. Just a theory, but in my experience, acetate
>will behave better if it's
>not super dry. I don't know of a great way to humidify it. Maybe leave it
>in a commercial greenhouse
>for a few days? Not the paper box, of course.Watch out for mold, too,
>there may be spores all over a
>greenhouse. Certain molds grow on and eat acetate, I know this for a
>fact. So maybe put it in a
>sealed oven at relatively low temp (maybe 100-120 degrees F, maybe less)
>with a water source that
>can evaporate and infuse the acetate over a time period? I'd experiment
>with a junker reel first! I
>can send you some edge-curled but not vinegar Scotch 111 to play with.
>Can't say if it would behave
>exactly the same way as the Japanese tape.
>
>By the way, there were several articles over the years in the SMPTE
>Journal about the long-term
>problems and breakdowns of cellulose (acetate) base for films. I assume
>the same problems and
>mechanisms described apply to thinner-base magnetic tapes. A lot of SMPTE
>Journals are online at
>archive.org, but maybe not the later era of which I speak (articles
>appeared in the 1980s).
>
>-- Tom Fine
>
>----- Original Message -----
>From: "Eric Jacobs" <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: Friday, January 29, 2016 7:13 PM
>Subject: [ARSCLIST] playback of disintegrating open reel tape
>
>
>We have a 1/4-inch open reel tape (TDK Synchrotape ca 1966 Japanese stock)
>that is quite literally disintegrating and cannot hold any tension.  The
>very slightest amount of tension causes the tape to snap.  The tape cannot
>even hold a leader without snapping.  We¹ve turned the tape tension way
>down
>on our Studer A820, but it can¹t be pulled through the transport without
>snapping.
>
>The tape is heavily curled along the edges (only the center 25% is flat)
>and
>is anything but straight from exposure to presumably high temperatures
>over
>the past 50 years.  The outer wraps have bonded to each other.  We can
>deal
>with the edge curl and the age-induced country-laning by using a custom
>mechanism that gently increases the tape wrap around the PB head (forces
>the
>tape flat) and additional edge guides fore and aft of the PB head that
>keeps
>the tape centered on the head.  We can even separate the outer wraps,
>albeit
>in 1-inch segments that would need to be spliced together ­ this seems
>like
>a bad idea, but I don¹t see any other choice if we want to get past the
>outer wraps.
>
>But it¹s the fragility of the tape (lack of tensile strength) that is the
>central issue.  If it were possible to ³back² the tape, it might keep it
>from snapping.  But how do you efficiently and reliably ³back² 1200 feet
>of
>tape that snaps with the slightest bit of handling?  And what do you back
>the tape with?  Splicing tape? It might be easier to apply backing to the
>centerline of the tape rather than the full width because of tape
>shrinkage
>and edge distortion, but then the resulting tape pack would probably be
>quite poor, especially if the backing doesn¹t stack precisely on top of
>the
>previous wrap.  Also, a narrow backing (like cassette splicing tape) may
>or
>may not affect the ability to force the tape flat at the PB head ­
>essential
>for a quality transfer.
>
>Looking for ideas and suggestions.
>
>~ Eric
>
>   Eric Jacobs, Principal
>   The Audio Archive
>   1325 Howard Ave, #906, Burlingame, CA  94010
>   Tel: 408-221-2128 | [log in to unmask]
>   www.theaudioarchive.com <http://www.theaudioarchive.com/>
>

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