As always, Richard has made some very astute comments regarding the
issue of re-hydration. I have only had experience with Magnetophon type
L tapes; the only type C tapes I have ever seen were in the Mullin
collection and a few reels in a couple of archives I've worked with.
Either way, you will need a set of modified guides for the 6.5mm tape (I
used a heavily modified Studer A-80 transport for most of these, which
required a bit of precision machining to get right, but other machines
with modified guides should work as well).
I used distilled water with a small amount of Kodak wetting agent, but I
don't think it makes too much difference. On most tapes, I've
re-tensioned the tape with a reverse (flipped) wind on the pack to
reduce cupping after about an initial 24 hour exposure, and then treated
it for another 24-48 hours before cleaning and playing. There are
probably some other viable approaches, but this has worked quite well on
a number acetate base tapes from the 1940's to the 1960's.
Scott D. Smith CAS
Chicago Audio Works, Inc.
On 12/9/2011 4:14 PM, Richard L. Hess wrote:
> Hi, Simon,
> I apologize for not responding sooner to your question.
> Magentophonband Typ C was produced up until 1944 when the factory
> burned in an industrial accident. From then until the end of the war
> (and beyond) Typ L was the only tape manufactured in Germany (as far
> as I know). Typ L is Luvitherm (PVC) and is one of the few homogeneous
> tapes ever manufactured. Typ C is a much more conventional coated
> acetate tape.
> When I transferred several dozen reels of Typ C (a total of 51 mostly
> Typ C and Typ L from the Mullin-Palmer collection and a few dozen more
> from the Eve Mullin Collier collection) all of the Typ C tapes played
> well, even though they were somewhat stiff. I can imagine that they
> have become even stiffer in the intervening years.
> I transferred a half dozen Tonschreiber B reels (also Typ C, if I
> recall correctly) a few years later for Stanford (these were part of
> the Ampex Museum Collection which is now housed at Stanford). These
> had been stored in metal cans as opposed to the cardboard boxes of the
> other collections (I also did a few reels of mostly Typ L for the
> Pavek Museum). These reels stored in metal cans were suffering from
> vinegar syndrome.
> The first caveat I have is that these tapes are 6.5 mm wide as opposed
> to 6.35 mm wide and if you are having difficulties playing them or
> they are bouncing around part of the issue may be binding in the
> guides. I ended up taking a file to the worn side of a set of fast
> guides in one of my Sony APR-5000 head assemblies in order to widen
> the guides to more easily accommodate the tape (I can loosen the guide
> and turn it back to a never-worn side for 6.35 mm wide tape).
> The one tape that I had from the Eve Mullin Collier collection that
> was very stiff (much like a carpenter's tape measure with the cupping
> in it) was of concern. This was the early (circa 1935) tape and was
> only made for about two years if I recall correctly). I called
> Friedrich Engel in Germany and we talked about it a bit. He suggested
> a process of hydration. I placed the tape above some water in a closed
> plastic storage bin for about 24 hours.
> When I removed the tape, it was like a silk ribbon--very pliable. The
> tape played fine (unfortunately, Mullin had used it as an experimental
> tape and there were only series of test tones on it. I ended up not
> digitizing it at all. Too bad, after all that work, but it proved the
> I tried rehydration once more with an acetate tape that had fallen
> behind a wood stove in Vermont and stayed there several winters. It
> was of no use because the edges of the tape were actually fused
> together in spots, so nothing would help. It appeared that the
> rehydration process weakened the tape, but the wood-stove treatment
> didn't do it any good previously.
> If you are looking for more information about acetate film, the Image
> Preservation Institute (IPI) at Rochester Institute of Technology has
> some information on their website.
> Some of their papers are cited in my paper on tape degradation that
> was originally presented at the Audio Engineering Society's 121st
> convention in October 2006 in San Francisco was published in the ARSC
> Journal in the Fall of 2008. It is available here:
> IPI is also a source of information on vinegar syndrome. As Tom
> mentioned, Kodak tape is quite susceptible.
> Here are a few links related to Vinegar Syndrome from my site,
> including the old German tapes in cans.
> Here is a list of many degrading tapes and the current thoughts of
> what to do with them.
> I see while I was typing this Don Tait mentioned rehydration.
> On 2011-12-08 6:48 PM, Simon Kunz wrote:
>> Dear all,
>> I would like to use camphor on a brittle acetate tape to smoothen it
>> and make it playable. I have recently read of this procedure for film
>> and I wondered if it would work in magnetic tapes as well.
>> Does anyone have some experiences with this kind of treatment? Are
>> there any published articles concerning this topic? (whether applied
>> to film as to magnetic tape)
>> The tape I would like to treat is a Magnethophon Typ C from 1943.
>> Every hint is appreciated! If you prefer you may contact me off-list.
>> Simon Kunz