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Re: [ARSCLIST] Fwd: Sticky AGFA PEM 469

Hi Goran:

Thanks for digging these posts up.

What Claus describes with Ampex sticky tapes is exactly my experience -- they go sticky again after about 30 days. What Claus did not touch on but has definitely been my experience is that there is audible deterioration after two or three bakings. Treble dropoff, fuzzy upper midrange, the kind of stuff you hear in a multi-track if it's been run thru too many times for endless punch-ins.

I have also had experience with some Ampex tapes so badly stuck together that even baking would not make them un-spool correctly. The oxide would be "glued" to the back-coat of the layer ahead of it and thus would rip the back-coat off and end up an unplayable mess. This was with tapes that had been under extreme storage conditions (basements, attics, garages).

As for 3M, I can say that Scotch 226 and 227 reels I've had the misfortune of dealing with behave pretty much like Ampex tapes. I've never seen this white film discussed in the old posts, just typical sticky-shed that is temporarily cured by baking. However, with 1-mil Scotch 227, I had to bake 18 hours and let cool 18 hours to make one pair of 3600' reels fully playable with no shedding. These particular reels happened to go back sticky within 2 weeks, because I tried to make another go at part of one and ended up with quickly discovering it was sticking and needed another baking. Luckily, the second pass worked great and those reels were disposed of later on.

I have a bunch of Agfa PEM 468 1/2" reels recently given to me. I will report back if I run into any troubles. The two I've played so far are just fine, and one was literally in a basement closet for at least a decade.

-- Tom Fine

----- Original Message ----- From: "Goran Finnberg" <mastering@xxxxxxxxx>
To: <ARSCLIST@xxxxxxxxxxxxxxxx>
Sent: Wednesday, April 02, 2008 11:11 AM
Subject: Re: [ARSCLIST] Fwd: Sticky AGFA PEM 469

Peter Brothers:

The microwave process is called the XT process. It is patented,

That´s correct.

I have saved this from the ARSC list in 2004 that gave some more
information coming directly from Terry O´Kelly of BASF:


ctrelby@xxxxxxxxxxxxxxx 9/28/2004 5:06:38 PM >>>

Hi John,

Welcome to the 70's tape pit. I'm sure you have heard about sticky-shed
syndrome etc.

Environmental law changes forced most tape manufactures to change the
formula of their binder in the early 70's. This has left us with
sticky-shed and other artifacts. Scotch/3M I have found not to exhibit
sticky-shed unless it was stored VERY poorly, but* A fine white powder
in many cases be released and distribute itself on the tape path and
It is very hard to see, and in many cases you have to look at the erase
(it's black) to see this. The powder is fine enough that it will slowly
deteriorate the Hi frequency play-back response during a pass.
The baking of tapes is not a fix-all solution. It was specifically
by a group of engineers from Ampex to solve the sticky-shed issues. AGFA
developed their own solution to the same problem. (I'll include an email
from a BASF engineer to our Video Director at the end of this posting).
such study was done by Scotch/3M to my knowledge but I have found that a
pass or two on a pellon based cleaning machine with light tension will
off the powder and render the tape playable. This process can also be
by hand if you are very careful.

I know this doesn't answer your question about TDK, but I have not
encountered tapes from the 70's from TDK, and have no direct solution
you. It sounds like and cleaning pass is in order for you, BUT PROCEED
CAUTION, and test on lengths of tape with no audio, since you might
the tape in trying to find your solution.

The following excerpt is from and email from Terry O'Kelly, formerly of
to Pat Shevlin, Xepa Digital. (130 @ 8hrs refers to 10.5" dia, 2" tape -
would still suggest this process is done by engineers with experience to
assure a successful result)*


"I do have good records of the Agfa XT process and the AMPEX process for driving water molecules out of the polyurethane binder. Agfa used a microwave, but the oven had to be so carefully controlled over a short period of time that it was not generally recommended for users. IDT in West Palm Beach licensed the Afga method, but I don't know if they are still around.

The Ampex method used a convection oven with an internal fan that moved
heated air around the tape.  The tape was slowly brought to a
temperature of
130 degrees F. for a period of about 8 hours.  Plastic reels could be
but it was better to have transferred the tape to a metal reel.  The
transfer process itself helps to redistribute tension in the tape pack
make it more uniform.  More than one tape required a spacer such as an
metal reel.  Once the tapes had cooled to the touch, they were good for
about 30 days; but copying the data as soon as possible was safest.  The
binder would begin to absorb water again after 30 days, but the linking
structure of the binder would be damaged enough that a second baking may
have prevented the oxide/binder combination from delaminating or rubbing

The goals of both the Ampex and Agfa methods were the same: drive the
molecules out.  The XT process was faster but more difficult without a
controlled environment.  The Ampex process was slower but easy to follow
most people."


I hope you find this helpful.


Claus Trelby
Managing Engineer/Partner

XEPA Digital
1137 Branchton Road, 19-N-3
Boyers, PA 16020-0137



Goran Finnberg
The Mastering Room AB

E-mail: mastering@xxxxxxxxx

Learn from the mistakes of others, you can never live long enough to
make them all yourself.    -   John Luther

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