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Author Topic: "Baking" old open-reel tapes  (Read 5685 times)

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Offline DSatz

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"Baking" old open-reel tapes
« on: December 07, 2020, 11:24:58 PM »
Hi. I've posted about the fact that I'm going through all the dozens of cartons of old tapes that I have in storage, and transferring them to digital so that I can (as the case may be) donate the originals or, for the most part, discard them. Many of the tapes are open-reel recordings that I made in the 1970s and early 80s on Ampex 406 and 407 tape. Those types of tape are at the epicenter of the "sticky shed syndrome"--the tapes are permanently ruined if you try to play them, unless they're gently baked in a convection oven at a controlled, low temperature first. See attached photo for some tragic results from this afternoon--remnants of the oxide layer of part of a tape; it separated from the backing when I pressed "stop" while winding the tape.

Since I have so many of these tapes, I decided to get my own oven, rather than to bring tapes by the dozens to a transfer engineer who does this baking as a side service. I'll only need it for maybe six months, but it takes me over an hour each way to get to and from his shop, so it makes relative sense for me. I plan to practice on a tape that's already badly damaged; then once I get the hang of it, I'll bake all Ampex tapes pre-emptively before trying to transfer them. My current understanding is that the temperature should be around 130 degrees Fahrenheit and the baking time should be maybe 4 to 6 or 8 hours. I sure hope this works ...

--best regards
« Last Edit: December 07, 2020, 11:26:38 PM by DSatz »
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Offline GLouie

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Re: "Baking" old open-reel tapes
« Reply #1 on: December 08, 2020, 01:22:08 AM »
DSatz, you missed my overview of tape baking at the August AES Tea Time Topics! PM me for the outline notes.

There is a wealth of info on the web, but some of it is old, some wrong, etc. and there is a lot to sift through. I suggest starting with the Ampex patent for tape baking, which suggests 52-54C (122-129F). Then the short answer to time of baking is that it depends. Many people recommend longer times now, it seems, such as 24 hours, where you used to hear 6-12 hours. This may be that the decomposition is now worse, or some people have 2 inch tape vs. 1/4 inch, or something else. Extra time does not seem to be harmful.

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Re: "Baking" old open-reel tapes
« Reply #2 on: December 08, 2020, 10:27:58 AM »
If I remembered any of the tricks of the engineers I worked with years ago I'd spew them out, but I'm familiar with oxide flying off a 2" tape like Pigpen just walked through the room. If the Ampex technique isn't working for some reason I'll ping a couple of those guys for you. Good luck.
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Offline GLouie

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Re: "Baking" old open-reel tapes
« Reply #3 on: December 08, 2020, 11:50:43 AM »
Yes, I've experienced one example of the oxide separating from the backing out of thousands of baked reels, so it does happen. I haven't seen any tips on preventing or predicting this.

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Re: "Baking" old open-reel tapes
« Reply #4 on: December 08, 2020, 07:09:00 PM »
I've also heard using a food dehydrator can in some cases provide good results as the temperature can in some cases be more consistent and precisely controlled. 
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Re: "Baking" old open-reel tapes
« Reply #5 on: December 08, 2020, 07:14:18 PM »
I've also heard using a food dehydrator can in some cases provide good results as the temperature can in some cases be more consistent and precisely controlled.
by definition they are low temp and high air circulation

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Offline GLouie

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Re: "Baking" old open-reel tapes
« Reply #6 on: December 08, 2020, 10:50:38 PM »
I've not used a food dehydrator, as we have an old surplus germ oven like this (but older):

https://www.sonicraft.com/tape-baking/

As long as the temperature can hold at 130F, with little overshoot, I think you are good to go. A home cooking oven seems to fluctuate way too much. To low a temp is also bad; you won't get much change in the tape even with a long bake time.

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Re: "Baking" old open-reel tapes
« Reply #7 on: December 09, 2020, 01:00:34 AM »
Double check temperatures using another thermometer.  Oven thermometers are often not exact and missing by a few degrees may cause problems.
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Offline DSatz

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Re: "Baking" old open-reel tapes
« Reply #8 on: December 09, 2020, 03:35:21 PM »
I ordered a thermometer and a food dehydrator; the thermometer arrived today. There isn't a lot I can do with just that, but it's a start.

GLouie, hi! Nice to see you here (as well as the other place). Unfortunately this forum doesn't allow files to be attached to private messages, but I'll send you my private email address--unless you'd like to post your notes as an attachment to a message here; it's up to you.

--best regards
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Re: "Baking" old open-reel tapes
« Reply #9 on: December 09, 2020, 04:47:09 PM »
I ordered a thermometer and a food dehydrator; the thermometer arrived today. There isn't a lot I can do with just that, but it's a start.

GLouie, hi! Nice to see you here (as well as the other place). Unfortunately this forum doesn't allow files to be attached to private messages, but I'll send you my private email address--unless you'd like to post your notes as an attachment to a message here; it's up to you.

--best regards

Upload to WeTransfer and use the link.  It's a 2 step process which is a workaround.   
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Offline DSatz

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Re: "Baking" old open-reel tapes
« Reply #10 on: December 09, 2020, 10:44:57 PM »
OK, my dehydrator has arrived and been tested, and tomorrow I'll try baking my first tape. (I may have to order a chef's hat from a costume store.)

But I have a question: The advice from various sources that I've seen seems to agree that tapes should be wound smoothly (e.g. "library wind") before baking them. I can certainly do that--but if possible I'd like to understand why it's important, and how important it actually is (or isn't).

--best regards

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Offline EmRR

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Re: "Baking" old open-reel tapes
« Reply #11 on: December 09, 2020, 11:44:22 PM »
But I have a question: The advice from various sources that I've seen seems to agree that tapes should be wound smoothly (e.g. "library wind") before baking them. I can certainly do that--but if possible I'd like to understand why it's important, and how important it actually is (or isn't).

--best regards

I think it's to avoid any chance of base deformation, as with long term storage. 
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Offline GLouie

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Re: "Baking" old open-reel tapes
« Reply #12 on: December 09, 2020, 11:58:03 PM »
You would need a transport with no fixed guides if you need to library wind a sticky tape before baking - somewhat rare. Sometimes you may not have much choice, but I think there are some physical changes going on and a smooth wind is better for the bake. For sure, the tape pack shrinks after baking and can be very loose - don't put it on a machine that is not gentle.

Offline DSatz

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Re: "Baking" old open-reel tapes
« Reply #13 on: December 10, 2020, 11:23:54 AM »
GLouie, the Nagra IV-S has no fixed guides in the path when a tape is being rewound, and the QGB large-reel adapter (which also has only rollers) gives further control over the tape tension.

But since my Nagra gear is in storage, for my first experiment I used a Revox A 77 with the tape going directly from one 7" reel to another, not passing through any guides or over any heads (which is beginning to sound like "over the river and through the woods"). If you hold down the play button, about 2/3 of the reel will shuttle from the feed side to the take-up side at a stately pace. The last 1/3 I drew across by turning the take-up reel manually. The tape pack is decently even--not perfect, but better than you'd get from a fast wind.

The cookie is in the oven now, set for 8 hours. Do you think with a 1/4" tape on a plastic reel, there's any point in flipping it at the 4-hour mark?
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Offline EmRR

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Re: "Baking" old open-reel tapes
« Reply #14 on: December 10, 2020, 12:05:06 PM »
I know I've seen warnings about plastic reels warping, I don't know offhand what the recommendations are. 
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Re: "Baking" old open-reel tapes
« Reply #15 on: December 10, 2020, 03:20:40 PM »
I might try an 8-track in the 'ol air fryer.

Seriously, this is a very interesting thread.
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Offline GLouie

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Re: "Baking" old open-reel tapes
« Reply #16 on: December 10, 2020, 03:34:56 PM »
I've never had a problem with plastic reels warping if the temperature is steady at 135F or so. Higher temps can cause a problem.
8 hours may be enough. I think it depends on the chemistry and storage of each tape. Many people tell me to do 24 hours - so I start at 10-12. I have no verifiable evidence that the longer time causes any damage, physical or magnetic, so longer may be safer as opposed to playing a tape that might have a severe case, and be underbaked. It is hard to determine how bad a tape is; I suppose you could try playing it and see how much scrapes off, if you dare.

I don't flip tapes, but I am lazy and it seems OK. Maybe if I did tapes wider than 1/4".


GLouie, the Nagra IV-S has no fixed guides in the path when a tape is being rewound, and the QGB large-reel adapter (which also has only rollers) gives further control over the tape tension.

But since my Nagra gear is in storage, for my first experiment I used a Revox A 77 with the tape going directly from one 7" reel to another, not passing through any guides or over any heads (which is beginning to sound like "over the river and through the woods"). If you hold down the play button, about 2/3 of the reel will shuttle from the feed side to the take-up side at a stately pace. The last 1/3 I drew across by turning the take-up reel manually. The tape pack is decently even--not perfect, but better than you'd get from a fast wind.

The cookie is in the oven now, set for 8 hours. Do you think with a 1/4" tape on a plastic reel, there's any point in flipping it at the 4-hour mark?

Offline DSatz

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Re: "Baking" old open-reel tapes
« Reply #17 on: December 11, 2020, 02:34:06 PM »
OK, here are my mixed results after 9 hours of baking at 135 degrees F, then letting it cool down for about a day before I got around to trying to play it.

The basic condition of the tape is greatly improved for much of its length. When spooling it between reels, I gently pinched a Kleenex tissue around the tape and only very, very little material came off, unlike before. But the tape was already so badly damaged before I baked it that most likely no part of it can be used any more. For much of its length it looks as though the tape is in the recorder backwards, with the oxide facing outward instead of inward toward the heads.

That's a shame; it was an audition tape that I remember making for a very good young conductor, who later went on to become rather well known.

The results were somewhat uneven, though. There are parts of the tape where the oxide layer still comes off in strips while winding it (see attached photos; in the one showing the Revox, what looks like tape wound partly over the left-hand reel is actually the oxide layer alone, which came off in lengthy strips while I was spooling the tape between reels--not winding it all that fast, either). So maybe Ampex is right, and 16 hours is better.

The clear plastic reel didn't warp at all that I could see.

--best regards

Edited later to add: This begins to make a kind of cruel sense to me. The oxide layer contains the binder that holds it to the backing. Once that binder becomes ineffective due to decomposition, the oxide layer has no preference for whether the "back" of it will remain with the layer of backing that it was originally attached to, vs. its "front" adhering to the "back" of the backing layer that it's pressed up against on the reel. It's a 50/50 proposition.

So as GLouie said (maybe in text that was added later? I don't remember seeing it before), it's better to have loved and lost--I mean, it's better to bake too long rather than not long enough--and in my opinion one shouldn't try to do ANYTHING with the tape before baking it. I'm not sure that I would advocate spooling it, no matter how gently and slowly, to improve the wind prior to baking; I think that I was wrong to do that in this instance.
« Last Edit: December 11, 2020, 02:58:20 PM by DSatz »
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Offline audBall

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Re: "Baking" old open-reel tapes
« Reply #18 on: December 11, 2020, 03:06:10 PM »
I wonder if the smooth winding (library wind) suggestion is intended to allow for a more uniform spacing/wind of the tape reel such that the later (convection) baking process would permeate/distribute the heat more uniformly (less "unevenly") throughout and around the tape.

Although I'm not sure how one would accomplish that if the reel needs to be baked just to be used.

/limited use comment

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Re: "Baking" old open-reel tapes
« Reply #19 on: December 11, 2020, 04:43:24 PM »
Happy to see this thread, and my condolences on the end result of that particular first test.  This gets me thinking again of some cassettes I should transfer, 'though I'm sure that will soon pass and I'll be able to put this out of mind again.  Anyone have experience baking cassettes?  Wondering if the the cases need be disassembled and spools removed, since plastic cassette housings are considerably thinner than most 1/4" tape plastic reels.  These are 80's era, stored for the past 25+ years, and I suspect would benefit from baking.  Some 4-track, some 2-channel masters.



« Last Edit: December 11, 2020, 04:49:04 PM by Gutbucket »
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Offline EmRR

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Re: "Baking" old open-reel tapes
« Reply #20 on: December 11, 2020, 11:13:01 PM »
Happy to see this thread, and my condolences on the end result of that particular first test.  This gets me thinking again of some cassettes I should transfer, 'though I'm sure that will soon pass and I'll be able to put this out of mind again.  Anyone have experience baking cassettes?  Wondering if the the cases need be disassembled and spools removed, since plastic cassette housings are considerably thinner than most 1/4" tape plastic reels.  These are 80's era, stored for the past 25+ years, and I suspect would benefit from baking.  Some 4-track, some 2-channel masters.

Word is cassettes don't need baking.  I've never heard of a gooey one.  Warped shells, leader splices gone bad, yes. 
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Re: "Baking" old open-reel tapes
« Reply #21 on: December 11, 2020, 11:18:44 PM »
I wonder if the smooth winding (library wind) suggestion is intended to allow for a more uniform spacing/wind of the tape reel such that the later (convection) baking process would permeate/distribute the heat more uniformly (less "unevenly") throughout and around the tape.

Although I'm not sure how one would accomplish that if the reel needs to be baked just to be used.

/limited use comment

This is what I was going to comment.  If you can loosen the wind, it would be more surface area/better.  But if the tape is stuck together, attempting that would ruin.  so...  :shrug:

I wonder if a 5* F lower temp for longer might be better than attempting a library wind?  I've never attempted this but definitely interested in the process.  I deal with a lot of heat transfer at work in a commercial sense.  I don't see a longer bake time being detrimental if the heat isn't too much and there's plenty of convection/flow.  We are talking about metals and plastics, not food.
« Last Edit: December 11, 2020, 11:20:52 PM by justink »
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Offline jerryfreak

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Re: "Baking" old open-reel tapes
« Reply #22 on: December 12, 2020, 12:01:58 AM »
I mean, it's better to bake too long rather than not long enough

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Offline DSatz

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Re: "Baking" old open-reel tapes
« Reply #23 on: December 12, 2020, 01:55:38 AM »
Actually I have one cassette (out of many hundreds that I've recently transferred) which I may want to try baking. The tape plays OK for a minute or two, but then begins to wander out of the path and pull out of the cassette on the supply side, while getting stuck on the take-up side (i.e. it "throws a loop" at 1-7/8 ips and I have to stop the tape).

I've exchanged the cassette housing twice already but that hasn't helped; I think it's the tape stock itself which is the problem. It's an Ampex-brand cassette, FWIW.

I'm sure I've read about other people who baked cassette tapes--just not nearly as often as I've read about open-reel tapes being treated. When I get to it, I'll let y'all here know whether it helps or not. I might well take the tape out of the cassette housing to bake it, just to eliminate one "unknown".
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Re: "Baking" old open-reel tapes
« Reply #24 on: December 12, 2020, 02:06:22 AM »
it seems the bad tape was era-specific?

i first heard of "baking" in 1990 when healy, et al were talking about it for mid-70s reels

as i type this, the common 80s cassettes are relatively twice as old as that, but perhaps they figured it out and were able to improve by then?
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Re: "Baking" old open-reel tapes
« Reply #25 on: December 12, 2020, 09:44:18 AM »
it seems the bad tape was era-specific?

I was told that certain formulations were more prone than others to deterioration.
« Last Edit: December 12, 2020, 10:07:44 AM by anodyne33 »
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Re: "Baking" old open-reel tapes
« Reply #26 on: December 12, 2020, 03:25:20 PM »
OK, here are my mixed results after 9 hours of baking at 135 degrees F, then letting it cool down for about a day before I got around to trying to play it......

Very sorry. I never personally spool before baking, and out of many hundreds, maybe thousands of baked Ampex 1/4 reels, exactly one had the oxide separate cleanly like that after baking. My guess is that you'd have had the same problem after baking.

Sticky shed is usually known on tapes that have backcoat, and apparently manufacturers started using urethane in the binder for the backcoat and the oxide layers. My feeling is that even among certain manufacturers and tape "models" that there is a wide variation in decomposition. I am guessing there is batch inconsistency as well as storage differences. In the USA, Ampex is most cited, but also 3M, Agfa, etc. Other tapes may have other problems that may make them seem sticky, and baking is not recommended.

There is one fellow who says to "simply" remove the back coat, which he says is the root cause of the problem. A few test demonstrations have apparently been successful, but he has yet to show a practical method of doing this.

Here are some references. I would probably start with the Richard Hess paper.


---Sticky Shed References from the 1980s-90s---

IASA Phonographic Bulletin #61, "Restoration of Tapes with a Polyester Urethane Binder" 1992

Studio Sound, May 1991 - Barry Fox's Business column, Sticky Shed Update

Studio Sound, December 1990 - Tape Life: An Era of Concern by Barry Fox

Audio, November 1990 - Archival Revival by Michael Stosich

Audio, July 1990 - Bert Whyte's Behind the Scenes column (I bake for Whales)

MIX, May 1990 - Philip De Lancie's Tape and Disc column "Sticky Shed Syndrome, tips on saving your damaged master tapes"

Recording Engineer/Producer, July 1988 - Studio Update:
Talkback: Binder Breakdown in Back-Coated Tapes by Scott Kent

JAES, April 1988 - Increasing the life of your Tape by Jim Wheeler, Ampex.

Broadcast Engineering, October 1987 - Preserving Magnetic Tape by Walter Davies (the LAST Factory)

IEEE Transactions on Magnetics, September 1985 - Kinetics of the Humid Aging of Magnetic Recording Tape, by H. Neal Bertram, Ampex.


---Other references---

The Ampex Patent
U.S. Patent 5,236,790


Richard Hess
Tape Degradation Factors and Challenges in Predicting Tape Life
ARSC Journal, volume 39, No. 2 (Fall 2008) page 240
http://www.richardhess.com/tape/history/HESS_Tape_Degradation_ARSC_Journal_39-2.pdf

Hess' personal site with tape degradation info for several tapes
https://richardhess.com/notes/formats/magnetic-media/magnetic-tapes/analog-audio/degrading-tapes/


Sonicraft (New Jersey) on tape baking
https://www.sonicraft.com/tape-baking/


Eddie Cilletti
If I Knew You Were Coming, I'd Have Baked a Tape!
http://www.tangible-technology.com/tape/baking1.html


Mike Rivers
Early article with caveats
https://mikeriversaudio.files.wordpress.com/2020/07/how-to-bake-a-tape_original_1990-article.pdf


ARSC (Association for Recorded Sound Collections)
Guide to Audio Preservation (CLIR pub 164)
https://www.clir.org/pubs/reports/pub164/


British Library
Manual of Analogue Sound Restoration Techniques
https://www.bl.uk/help/manual-of-analogue-audio-restoration-techniques


IASA (International Association of Sound and Audiovisual Archives)
TC03 (general planning), TC04 (restoration guides)
https://www.iasa-web.org/tc04/audio-preservation
Web version free to public; PDF free to IASA members; paperback for a fee.




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Re: "Baking" old open-reel tapes
« Reply #27 on: December 12, 2020, 08:36:17 PM »
Ah sticky shed. 

I've finished a project for a radio station on old reel to reels, literally about a 200 reels.  We baked them all in a food dehydrator at the lowest setting, for about 4 hours minimum, overnight was the longest.  Transcribe the tapes immediately.  Well, wait until they cool, then transcribe them.

Perhaps it goes without saying but gently fast forward and reverse the tapes to loosen them up before transcription.  Of course, clean and demagnetize your heads. 
Regards,
Scooter123

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Offline DSatz

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Re: "Baking" old open-reel tapes
« Reply #28 on: December 13, 2020, 09:45:26 PM »
I put the tape back into the dehydrator for 16 further hours of baking, let it chill out for a day and a half, then transferred one movement of the Beethoven Seventh Symphony using the Nagra that the tape had been dubbed on ~40 years ago. The attached photos show the disastrous result.

Please keep in mind that this tape wasn't wholly typical, because it had already been damaged badly by trying to rewind it; the oxide/binder layer in many places came off the backing layer that it belonged on, and either flew off in random directions or stuck instead to the back of the backing on the adjacent layer of tape on the reel. Note one peculiar thing that occurred sometimes during playback: An oxide/binder layer and a backing layer fed through the tape path at the same time, but separately (see the two arrows that I added to the second photo below). My apologies for shadowing my own photographs, but the only light source was overhead.

What I'm not seeing--and what gives me hope for later work with tapes that haven't been "pre-ruined" before baking--is any of the sticky stuff on the heads, guides or rollers that came off in large amounts the first time I tried to play any of this tape. All this loose oxide/binder stuff very well might have separated from its backing before I baked the tape. (At least I hope that's true.)

(And now if I want to send holiday greeting cards to my engineer friends, I have the photos!)

edited later to add: What also gives me hope: As I've transferred this tape piece by piece, I've stopped to clean up between pieces--then I've rewound the tape slightly so as to get the correct transitions between the pieces. Whatever material had come off the backing while playing each piece, when I rewound to the end of the previous piece and then played again from there, no further material came off until I got to the part I hadn't played before.
« Last Edit: December 13, 2020, 11:29:20 PM by DSatz »
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Offline EmRR

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Re: "Baking" old open-reel tapes
« Reply #29 on: December 14, 2020, 12:04:56 AM »
Holy crap that is a nightmare to look at!
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Offline DSatz

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Re: "Baking" old open-reel tapes
« Reply #30 on: December 17, 2020, 02:02:37 PM »
Yeah, it kind of made me want to avoid dealing with these tapes, knowing that they could fall apart like that. But I've got ~40 cartons of them, and they won't deal with themselves. So I've cautiously pressed onward.

The second reel that I baked, I left in the oven for 18 hours and it transferred very nicely. No shed, no sticky. One of the pieces on it actually sounded rather spectacular if I do say so myself: a Dolby "A" Nagra recording of a piece by a respected modern composer, for solo trombone and what sounds like about ten other wind instruments, recorded in what sounds like a church. (There were no markings on the box, just a label on the tape that said "G Lewis" with a Dolby symbol.) I was able to track down the composer (a trombonist himself and very likely the soloist), so that I can send him his tape after all these years, if he still wants it.

The thing is, I have no way of knowing whether that tape would have had problems if I hadn't baked it. So I'm still being cautious. I've got two tapes in the oven now, one of which has the slight, white dusting on it that indicates a problem, but the box says that it's a copy, so I'm feeling a little bolder. The other doesn't show any outward signs but it's a tape that was lent to me, so it may not be on Ampex stock, though it's at least similar-looking.

--best regards
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Re: "Baking" old open-reel tapes
« Reply #31 on: December 17, 2020, 02:54:36 PM »
My general feeling is that if it's back coated tape from the 70s on up, especially Ampex, to just bake it. It's not worth the time IMO, to try playing such a tape beforehand to check the stickiness. It's 99.9% sure to have it, and I prefer to take the risks of baking first over the risks of playing first and scraping off oxide.

If its any consolation, I've only had 1 tape completely separate like that. I have had some tapes separate and transfer oxide to the adjoining layer in the last few inches around the hub, which usually has no or less important content. My theory is that there was more tape pack tension/compressing at the hub, and/or perhaps more baking would've helped. Based on the looseness a just baked tape pack has, I think an untreated tape pack must have swollen and is packed very tightly.

Offline DSatz

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Re: "Baking" old open-reel tapes
« Reply #32 on: December 21, 2020, 07:53:43 PM »
> My general feeling is that if it's back coated tape from the 70s on up, especially Ampex, to just bake it.

That's what I decided, too. I wonder whether that first tape might have been saved if I hadn't rewound it first (sigh).

Meanwhile I've had three solid successes after baking the tapes for 18 hours. A little bit of white powder comes off while playing the tapes, but it sticks to the erase head and doesn't interfere with the transfer. Also, splices within recordings have held up so far, but with some splices between recorded tape and white leader tape, the splicing tape holds on to the recording tape but lets go of the leader tape, so I have to redo those.

--best regards
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Offline GLouie

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Re: "Baking" old open-reel tapes
« Reply #33 on: December 23, 2020, 12:55:57 PM »
I would ask Rich Hess if he thinks the complete peeling of coatings would've been fixed if not run first. I suspect not.

Splices are another matter. Generally, we have mostly Scotch white splicing tape and later on, some blue. I bake, then spool in library mode to check splices and general condition, and repack. If the splices seem to be holding, I go for a transfer, trying to listen carefully for audible anomalies especially at splices - sometimes they can slip a bit. Sometimes, the original splice is just at a bad spot (these are not commercial release recordings). Sometimes, the splice has left some goo on the adjacent layer of tape (usually at the edges), causing a stick-bobble during play. On these I use a dry soft cotton wipe to try to reduce the goo enough to play without damaging the oxide. Sometimes the splice just falls apart, in which case it has to be redone. I have been using a bit of Goo-Gone on a cloth to try to remove adhesive residue; put the tape end on a pad of paper, wipe longitudinally down toward the end of the tape, of course. I can usually remove most adhesive without taking off much, if any, back coat. Then re-do the splice. I try to take care since Ampex polyester will stretch rather than snap if deformed. Goo-Gone appears to be a lemon-scented oil type adhesive remover; alcohol would remove the coatings immediately. I have no clue whether Goo-Gone is doing other harm either short or long term, but consider these transfers to most likely be the last time these reels will ever be touched.

Sometimes I have to do a transfer 2-3 times if enough problems crop up, including just getting the levels wrong. It seems I can surf the web and still hear most, if not all, anomalies during a transfer!

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Offline DSatz

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Re: "Baking" old open-reel tapes
« Reply #35 on: January 01, 2021, 10:35:55 AM »
I've run about 30 "baked" tapes now. Nearly all have transferred cleanly, with only occasional, minor powdery "stuff" (some white, some black) coming off the tape.

But two large reels of Ampex 406--both halves of a concert I'd recorded in January, 1980--have been the exception. My notes say that I had played them in 2008 without noticing problems. But yesterday they both put out significant amounts of sticky black gummy stuff when played. It cleans off easily with 91% isopropanol, though the density of discoloration on the Q-Tips is remarkable, and it seems particularly attracted to the capstan on my Revox. One reel had longer, continuous pieces than the other, so I couldn't readily stop every five minutes to clean; after a while, the substance coated the capstan to the point of producing audible flutter. (The music was a Mozart wind octet, so the flutter was more distracting than it would have been, say, with string music.) Fortunately my transfer from 2008 is adequate.

Since the one big disaster that I had (photos shown above), I'm wondering whether there will be problems with other tapes that undoubtedly had some precursor of the problems in 2008, but that I played then anyway without baking. Maybe I shouldn't try to re-transfer those now, even though I have a better A/D converter than I had then, and (since the tapes will be going to an archive) this is my last chance at them.
« Last Edit: January 01, 2021, 10:38:05 AM by DSatz »
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Offline GLouie

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Re: "Baking" old open-reel tapes
« Reply #36 on: January 01, 2021, 02:48:14 PM »
If really black, it would seem to be the backcoat. Maybe go for a longer bake time? Is the Revox worse than the Nagra?

Offline DSatz

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Re: "Baking" old open-reel tapes
« Reply #37 on: January 02, 2021, 11:13:09 AM »
It does seem to be primarily a carbon suspension of some kind, and the oxide layer itself seemed OK on these two tapes. But I don't know that further baking (I'm already up to 18 hours) would help hold that stuff onto the backing. I think this is a rather different problem from the one that the baking process was designed to help with. Fortunately I'd made a decent transfer of those reels in 2008 (or unfortunately, if by doing so I caused this problem to occur now), but in any case I decided to go on to find, or create, other problems.

I say "create" because yesterday I inadvertently mishandled a reel that was off of its flanges, and in trying to get it back together, made it worse, creating the worst tape salad that I've ever had in my life. It's tempting to treat it as New Year's confetti--but since time has no meaning these days, I will spend at least a few hours today trying to reclaim the tape. It could be another one that I transferred in 2008--I have to play it to make sure; its exact contents are unidentified--but maybe it's not.

--best regards for 2021
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Offline GLouie

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Re: "Baking" old open-reel tapes
« Reply #38 on: January 02, 2021, 12:40:55 PM »
Sorry about the salad. It might be theraputic to watch a movie while putting the tape back on a spool.

I am hearing more people say to bake at least 24 hours, even 48 hours. My feeling is that if it's black, it's backcoat and inconsequential if some scrapes off, assuming it doesn't interfere with playback mechanics.

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Re: "Baking" old open-reel tapes
« Reply #39 on: January 11, 2021, 09:53:30 AM »
I need to find white cotton gloves to wear when straightening out the tape. Even with my glittering New York social life nowadays, my valet tells me that I don't have a pair of those in my dresser drawer. This is dreadful; whatever shall I wear now with my tuxedo and top hat, monocle and white-tipped cane? I must dispatch my butler to the haberdashery post-haste.

--The tapes are almost all in good mechanical condition after baking, but the ones that were recorded without noise reduction sometimes have levels of print-through that will limit their usefulness, other than as mementos. Even Dolby "B" makes enough difference to matter there. I'm being more critical than some other people probably would be, plus I'm mostly listening over headphones, but it's still sad. OTOH the ones recorded with better noise reduction systems, such as Dolby "A" or telcom c4, still sound awfully good if I do say so myself, depending on the miking and the performance.
« Last Edit: January 11, 2021, 10:10:39 AM by DSatz »
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Offline EmRR

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Re: "Baking" old open-reel tapes
« Reply #40 on: January 11, 2021, 11:45:06 AM »
I've been transferring a lot of 30ish year old cassettes lately, and it's the first time I've really noticed print-through in that format.  Dolby doesn't seem to make much difference here.   I did find one tape with dBX type II NR (made on a 4 track machine?) and found the dbx type I modules I have to be 'close enough' for the job, even though they aren't supposed to be appropriate. 
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Offline morst

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Re: "Baking" old open-reel tapes
« Reply #41 on: January 11, 2021, 04:33:24 PM »
I've been transferring a lot of 30ish year old cassettes lately, and it's the first time I've really noticed print-through in that format.  Dolby doesn't seem to make much difference here.   I did find one tape with dBX type II NR (made on a 4 track machine?) and found the dbx type I modules I have to be 'close enough' for the job, even though they aren't supposed to be appropriate.
I did a bunch of transfers in approx 2009 using incorrect DBX type I modules for cassettes recorded with DBX (Type II is correct for cassettes)

Since then, I did a little looking and gearsluts, I think it was, indicated that the DBX 224X-DS is the highest quality DBX Type II converter.
So I bought one.
They come up on ebay, usually in the range of $100-300. Hint, I paid more like $100, delivered.
Have not used it yet, but it lights up. Gotta get to my storage unit and get a box of DBX masters, and then get a deck I trust, that's worth passing the tape across the heads!

Ah maybe it was tape heads
https://www.tapeheads.net/showthread.php?t=4801


random example (band changed their name last year due to social issues)
https://archive.org/details/dixie1991-10-16-flac16/
« Last Edit: January 11, 2021, 04:35:49 PM by morst »

Offline EmRR

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Re: "Baking" old open-reel tapes
« Reply #42 on: January 11, 2021, 04:54:46 PM »
I did find one tape with dBX type II NR (made on a 4 track machine?) and found the dbx type I modules I have to be 'close enough' for the job, even though they aren't supposed to be appropriate.
I did a bunch of transfers in approx 2009 using incorrect DBX type I modules for cassettes recorded with DBX (Type II is correct for cassettes)

Since then, I did a little looking and gearsluts, I think it was, indicated that the DBX 224X-DS is the highest quality DBX Type II converter.

Cool.    Good to know the 224X-DS is considered best, I couldn't make out any real differences in a first look. 

My type I are 411 cards in a 900 rack along with other dbx cards, so I'm looking for a 942 card or two first, but that might prove more expensive.  There's also the 408 card, but I'd need 2-4 of those. 
« Last Edit: January 11, 2021, 04:58:06 PM by EmRR »
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Offline morst

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Re: "Baking" old open-reel tapes
« Reply #43 on: January 12, 2021, 09:09:47 PM »
Back in 2009, I used the DBX150 which is a single-rack-space unit, not really a module.
(photo from ebay)

Offline 108Ω

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Re: "Baking" old open-reel tapes
« Reply #44 on: January 15, 2021, 04:44:25 PM »
On tape-baking:
I've always wondered that if stored in super-low humidity for, perhaps, two weeks, would the moisture expel more safely than with heat ?
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Offline Scooter123

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Re: "Baking" old open-reel tapes
« Reply #45 on: January 16, 2021, 05:09:17 AM »
That’s possible. The glue that held the oxide coating breaks down and goes a couple steps from a solid to a liquid. Dry heat at a temperature below melting temporarily solidifies that glue. Mere dryness without heat might work.

Sticky shed as it is called is a bitch.
Regards,
Scooter123

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Offline 108Ω

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Re: "Baking" old open-reel tapes
« Reply #46 on: January 20, 2021, 01:06:55 AM »
That’s possible. The glue that held the oxide coating breaks down and goes a couple steps from a solid to a liquid. Dry heat at a temperature below melting temporarily solidifies that glue. Mere dryness without heat might work.

Sticky shed as it is called is a bitch.

You'd think that somewhere the industry would have released a bit of tape formula science.
Like that article from the retired (3M ? / BASF?) dude that I cannot find...

Liberal media:
https://www.npr.org/sections/npr-extra/2012/05/30/153917107/a-sticky-situation-baking-the-tapes
« Last Edit: January 20, 2021, 01:12:00 AM by 108Ω »
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Offline moondust.and.solitude

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Re: "Baking" old open-reel tapes
« Reply #47 on: January 27, 2021, 05:42:13 AM »
This topic has been an amazing read. There really should be a documentary made about the preservation of analog tapes as it's a true work of art.

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Re: "Baking" old open-reel tapes
« Reply #48 on: February 21, 2021, 11:40:08 PM »
The tape "pancake" that came apart on January 1: Over the past week I finally overcame my dread, and in three separate sessions, spent about seven hours unknotting it (with white cotton gloves on) and putting it onto a reel.

Then I baked it again (because it had been more than a month since the first time), and tonight I transferred it. It sounded quite good overall, though some of the levels on the tape were a bit too hot and there was a little distortion on some peaks. Fortunately it was a 15 ips recording, which tends to help conceal minor amounts of physical damage a lot better than 7-1/2 ips. And it was Dolby "A" encoded, which prevents print-through from being a problem most of the time.

Before and after photos are attached.
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Offline morst

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Re: "Baking" old open-reel tapes
« Reply #49 on: February 23, 2021, 02:55:23 PM »
Before and after photos are attached.
Now that's dedication!
Good going!
Could have done a 1000 piece jigsaw, but this is cooler.

 

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