This is where AMIA and ARSC can benefit from one another.

The members of AMIA have been dealing with Vinegar Syndrome (VS) for 
many more years than audio people with acetate based audio tape (acetate 
based motion picture film has been around since the late 1920's / early 
1930's). There are storage recommendations and standards for acetate 
based motion picture film that have been published many times and tools 
one can easily find to help identify even minute beginnings of VS, such 
as AD strips from the Image Permanence Institute at RIT:

 From my humble experience, all acetate based media slowly breaks down. 
Without the ability for acetate based media to "gas-off" so to speak, 
acidic acid leaches out of the acetate base and the vapors are contained 
with the media. VS begins and the vapors become more and more dense. As 
the density increases, the acetate breaks down and VS increases 
logarithmically. You see this all the time with motion picture films 
stored on old metal reels in old metal tins that do not allow the film 
to breathe. The only time I have found acetate based audio tape with VS 
is with the same storage parameters - the reel was placed in a 
protective plastic bag, then in the standard cardboard box, or 
protective air tight plastic audio box or the reels were placed together 
in an air tight plastic container. The audio tape could not breathe or 
gas-off and VS began. From my understanding, VS breakdown can be halted 
(but not reversed) by using cold storage methods. Again, I am not an 
expert but it is my understanding that you can halt VS at storage temps 
just above freezing, freezing is not required.

Motion picture film is frozen all the time. The key is how the film is 
prepped and packed prior. Also how the film is unpacked and 
re-acclimatized to the environment prior to working with the film again 
in standard room conditions. Although the base is the same, there is 
obviously a difference between acetate based motion picture film and 
audiotape because of the medium that is on the acetate carrier. It is 
possible that the binder in acetate based audiotape is less forgiving 
than motion picture film emulsion when frozen - but again, another good 
question that may have some good answers from AMIA, as these folks work 
with and store, a lot of full coat and mag stripe acetate based audio 
recordings which are surrogates to the visual motion picture film.

Tom, I know you're relatively speaking, but I would not want someone 
inexperienced reading this post thinking warmer/wetter is a better 
storage condition for acetate based media. Warmer and wetter than 
freezing - yes, but the warmer and wetter the storage conditions above 
freezing, combined with the inability for the medium to gas-off, the 
better the chance for VS to begin with acetate based media. I have 
clients on almost a weekly basis bring in motion picture film to 
transfer, who thought that the home basement or below ground office 
storage was the best place to store their movie film. Yes, the temps are 
slightly cooler than the rest of the building, but RH is definitely 
higher in a room "below ground level". This is where I see the bulk of 
the VS movie film coming in - when the client has stored the film in a 
basement in a metal tin. I rarely get film with VS that has come from an 
air conditioned house or business where the film has been stored on the 
first or second floor. This tells me that VS is triggered more by 
humidity than temp.

On the topic of sticky shed, folks from AMIA also deal with a LOT of 
sticky shed. I'm now baking almost as many videotapes as I do 
audiotapes. And the videotapes, like the audiotapes that require baking, 
are the professional back-coated tapes. Most often they are open reel 
videotape formats although I see more and more 3/4" U-Matic tapes and 
other older format cassette tapes that require baking. I'm not sure 
myself if cooler less humid storage conditions help to mitigate sticky 
shed. It's interesting because a client came to me three weeks ago with 
reel to reel tapes that he claimed were properly stored in a climate 
controlled vault. They were 3M/Scotch 206 audiotapes. They had the 
typical sticky shed and required baking even with the climate controlled 
storage. I'm not sure what freeze drying would do to a tape, but it 
might be interesting to see if this might be an alternative to baking. 
I've talked to several companies in the past that specialize in disaster 
relief. Their standard practice is to freeze dry everything (in these 
cases it is contents from an office building or home and AV media just 
happened to be caught up in the mix). I'm wondering what the effects 
were on the media?

For what it's worth...

John Schroth

On 3/1/2015 11:20 AM, Tom Fine wrote:
> Hi Richard:
> I worry that below-freezing storage of acetate media may freeze-dry it 
> out and make it so brittle that eventually it has no plasticity. If 
> super-cold/super-dry storage staves off severe sticky-shed and it can 
> be proven to really do that over time, then I would say it's the way 
> to go on that quantity of polyester-backed tape prone to sticky-shed 
> (I've heard estimates of 25-33% of tapes in vaults; I'd say it's 
> probably closer to 25% given the long history of tape recording before 
> polyester back-coated tapes, the fact that not all polyester 
> back-coated tapes develop sticky-shed, and the fact that there is no 
> consistent data showing that "post-sticky-shed" formulations didn't 
> solve the problem, and tape was used for quite a while after the 
> problem was said to be solved).
> It may well be that sticky-shed tapes need to be stored in a special 
> way, by themselves. Much like nitrate films (maybe even in the same 
> vaults, because I think they both need the same storage conditions). 
> Everything else should probably be stored in somewhat warmer, somewhat 
> wetter conditions. But, we're all just speculating until there's more 
> reliable science on this. I do speak from decades of experience owning 
> and using old acetate tapes, however.
> -- Tom Fine
> ----- Original Message ----- From: "Richard L. Hess" 
> <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Sunday, March 01, 2015 10:58 AM
> Subject: Re: [ARSCLIST] Distressing data point for upcoming ARSC tape 
> playback workshop
>> Hello, Tom,
>> This is a wonderful post. Without actually stating this, you 
>> highlight the challenge we all face by NOT having adequate scientific 
>> analytical backup to help direct the care and physical restoration of 
>> various media. Of course, after PrestoSpace found that the same 
>> manufacturer tape type number could apparently represent four 
>> different formulations over time, we learned that the project is 
>> daunting if it is doable at all with any accuracy in an affordable 
>> manner.
>> I have a couple of addenda to help round out this picture. I agree 
>> that more work needs to be undertaken and it is getting late to do 
>> it. I have spoken of your concerns whenever I thought it would make 
>> an impact as I know this is not the first time you have semi-publicly 
>> stated them here on ARSCList.
>> (1) I believe, at least here at Library/Archives Canada, that FILM is 
>> kept cool and dry but well BELOW FREEZING (of water i.e. WELL BELOW 
>> 0°C / 32°F. If you want an idea about how well below, my GUESS is 
>> -20°C / 4°F. I also believe that this level of cold does help stave 
>> off "vinegar syndrome."
>> (2) When I had an informal meeting with the good folks at the Library 
>> of Congress (I think it was late June 2012), I started talking about 
>> the extended baking times several of us have independently reported 
>> and they claim that is not needed in their work. I confirmed that 
>> they are working with "captive" tapes from their vaults. I do think 
>> this is a clue that cold/dry storage is reducing the severity of 
>> sticky shed syndrome.
>> I am blind copying a few people to make certain this information gets 
>> out there.
>> Thanks again!
>> Cheers,
>> Richard
>> On 2015-03-01 9:46 AM, Tom Fine ([log in to unmask]) wrote:
>>> I am right now working with tapes from 1959 and 1961, 3-track 1/2"
>>> tapes, with splices "replaced" in 1971 (according to documentation on
>>> the boxes) and, in the case of 4 reels, splices cleaned and/or replaced
>>> in the early 1990s. Alas, every splice so far has needed new cleaning
>>> with Naptha and many of them -- even those cleaned and successfully
>>> played in the 1990s -- have required full replacement.
>>> The replacement splicing tape put on in the 1990s has proven mostly
>>> stable but there has been some ooze and stiction around some splices. I
>>> tend to believe that is leftover ooze from non-complete cleaning of the
>>> original splices before replacement, but it could be new ooze over the
>>> past 20 years.
>>> Bottom line is that there seems to be no "permanent" splicing tape, it
>>> all seems to ooze and/or dry out over time.
>>> Another distressing datapoint ... This is the second batch of late 
>>> 1950s
>>> Audiotape acetate-backed tape I'm dealing with that has become very
>>> brittle, like most of the plasticity has dried out of the backing. I
>>> suspect this is made worse by over-dry storage conditions intended to
>>> somehow "prevent" or "mitigate" sticky-shed in later tapes (and 
>>> remember
>>> that there is no proof that dry storage does either). I wish some
>>> scientists would do some chemistry on acetate tapes and come up with
>>> better storage recommendations. There are millions of acetate tapes and
>>> films being stored under the same "keep it super-dry and cold" mandates
>>> that are imposed on polyester media (and these conditions DON'T stave
>>> off sticky-shed and DON'T make sticky tapes play longer after baking --
>>> all credible research and experience so far shows that ALL tapes prone
>>> to sticky-shed go sticky on their own, that baking allows playback, and
>>> that ALL sticky-shed tapes go back sticky a certain time length after
>>> baking; the only exceptions might be -- still not widely tried or 
>>> proven
>>> -- the Richardson method of chemically removing the back-coating).
>>> Incredibly, these old tapes still sound damn good on playback, and are
>>> able to move through a tape transport correctly after the splices are
>>> cleaned and repaired. I don't know if this will be the case at some
>>> future date. Luckily, these tapes I'm working with are backed by 
>>> funding
>>> for Plangent Process high-resolution transfers and defluttering, so the
>>> resulting digital assets will be very high quality.
>>> My recommendations, based on this experience:
>>> 1. I've now cleaned enough gooey splices with Naptha to be convinced
>>> that it is effective and safe for this job.Note that many hardware
>>> stores carry a can or two or no Naptha at all. It doesn't seem to be
>>> widely used by professional painters anymore.
>>> 2. It's been helpful to carefully detach the reel flanges -- while the
>>> tape end is taped down to the adjoining layers and the reel is not
>>> loose-wound -- and carefully (on a flat surface) clean all visible
>>> splice ooze (bubbles and chunks of white goo) with Naptha. I put the
>>> flange back on and flip the reel over very carefully, then do the same
>>> on the other side. Sometimes -- not always -- this mitigates stiction
>>> between layers around the splice, preventing even slight oxide 
>>> damage on
>>> the edges.
>>> 3. It is important to inspect the layers before and after the splice,
>>> and clean all residule goo off both sides of the tape.
>>> 4. Very gently deal with the splice itself. It can sometimes be gently
>>> coaxed up intact -- this happens about 50% of the time with original
>>> splices on these tapes. When that happens, clean the splice edges and
>>> center in particular, this is where the ooze will be. When the splice
>>> separates, I put a good dab of Naptha on the side stuck to the
>>> tape-pack, cleaning especially the center of the splice. Almost always,
>>> a gentle coax with the Q-tip with them lift the splice up so it can be
>>> repaired. When this doesn't happen, I used a chopstick that I whittled
>>> down to a blunt but pronounced "shovel" point. No splice points mangled
>>> so far with this. I then clean both sides of the splice, both sides of
>>> the tape, with a good dose of Naptha. By the way, change Q-tips
>>> regularly because the accumulated sticky ooze stays on the Q-Tip after
>>> the Naptha evaporates. Then I repair the splice (use a high-quality, 
>>> non
>>> worn-out splicing block, which isn't always to acquire these days). I
>>> use early 2000's vintage white-colored semi-clear splicing tape. I 
>>> don't
>>> at all like this newest thicker blue-colored splicing tape (which seems
>>> to be the only option these days). Luckily, I have a large store of
>>> old-style splicing tape.
>>> 5. When playback and transfer is complete, make sure to attach the end
>>> of the reel to the adjoining tape layer (if it's stored on a hub) or to
>>> the reel flange with NEW and EFFECTIVELY STICKY tape. An enemy of old
>>> tapes, especially acetate tapes, is storage under loose-wind 
>>> conditions.
>>> The acetate expands, contracts and sometimes gets vinegar syndrome. If
>>> it is stored tight-wound with the end taped down, it is less likely to
>>> get edge-warp.
>>> 6. Under ideal archival conditions, without tight production deadlines
>>> and with unlimited funding, I would say replace all old splices as SOP.
>>> Under real conditions, this is not always possible. Because of that,
>>> expect to go through this same procedure again if the tape is played
>>> again in the future. And, given my experience with 1990s splices, I'm
>>> not sure that modern splicing tape is any better about eventually 
>>> oozing
>>> glue or drying out.
>>> 7. This probably goes without saying, but demagnetize the tape path, 
>>> all
>>> metal tools, and work on the splice repair on a non-magentic surface.
>>> 8. It also probably goes without saying, but use Naptha in a
>>> well-ventilated area. John Chester turned me onto putting in a little
>>> squeeze-bottle with a needle tip and then squeezing a few drops onto a
>>> Q-Tip rather than having an open container and dipping Q-Tips into 
>>> that.
>>> This method really keeps the fumes to a minimum in a normal-sized room.
>>> I keep a low-speed fan blowing air across the tape transport to move
>>> what fumes do escape away from my face.
>>> -- Tom Fine
>> -- 
>> Richard L. Hess                   email: [log in to unmask]
>> Aurora, Ontario, Canada                             647 479 2800
>> Quality tape transfers -- even from hard-to-play tapes.

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