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Just got in 20 R to R tapes for restoration...
Old 17th April 2022
  #1
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Thomas W. Bethe's Avatar
 
1 Review written
🎧 15 years
Just got in 20 R to R tapes for restoration...

All of them except one are back coated and all the back coated tapes need baking.

Luckily we have the proper equipment for the task.

I find 110 degrees for 10 hours works well. What temperatures and times are others using for baking? We have a professional Dehydrators that has been modified for exact temperature control. Should be an "interesting" project.
Old 17th April 2022
  #2
Lives for gear
 
🎧 10 years
We go for about 130F for 12-24 hours, as per the Ampex patent. We only do 1/4 inch reels.

I hear anecdotes that needed bake times seem to be longer nowadays, but it will vary.
Old 17th April 2022
  #3
Gear Maniac
 
🎧 5 years
The time is only ever a guesstimate of course as it depends on how bad is the problem. But I would normally expect to use a higher temp than 110 deg F, perhaps 120 as a mid range figure. The wider the tape format, the longer time needed of course. Not all back coated tapes need baking. What brand and type are they?

I read recently details of a "droplet test" to gauge how badly affected is the tape. Will try and find it.
Old 18th April 2022
  #4
Gear Head
 
🎧 15 years
I highly recommend this conference paper presented by Federica Bressan in 2018 at the NAVCC:

The Impact of Thermal Treatment on Magnetic Tapes: An Exploratory Study Combining Chemical Analyses and Audio Features
https://www.aes.org/e-lib/browse.cfm?elib=19593

Essentially, their test used a methodology of incubating tapes at 54Β°C (129.2Β°F) with an 8-hour ramp up from room temperature, followed by a plateau of 48 hours, to an 8-hour ramp down. They used several varieties of tapes and plotted the results, which was absolutely fascinating. The science on this is still evolving but it's certainly a studied procedure in controlled environments. We've since adopted this method for all of our backcoated quarter-inch with great success. We use the same temperature for other tape widths (1/2," 1", 2"), however we adjust the times based on the condition & age - usually up to 7-10 days for older 2" Ampex & Scotch varieties.

The 'droplet test' was presented at the same conference and was equally as interesting! That paper can be found here:

Understanding Magnetic Tape Degradation by Polymeric and Material Testing
https://www.aes.org/e-lib/browse.cfm?elib=19590

Last edited by gunofason; 18th April 2022 at 03:03 PM..
Old 18th April 2022 | Show parent
  #5
Gear Maniac
 
🎧 5 years
Thanks for the links which I hadnt been able to find on another forum.

Quote:
Originally Posted by gunofason ➑️
...Essentially, their test used a methodology of incubating tapes at 40Β°C (129.2Β°F)...
40 deg C is 104 Deg F, not 129.2 Deg F.
Old 18th April 2022
  #6
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Thomas W. Bethe's Avatar
 
1 Review written
🎧 15 years
Thanks for the link. The tapes are all in white boxes with the person's name and their contents listed but no mention of the tape # or the manufacture. A few of the tapes are shedding badly with the back coating literally falling off the tape and sitting in the box. One of the tapes is reddish brown but again no label as to what the tape is. According to the owner they were all stored in a "home environment" and all from the early 1980s. It will be an interesting project to say the least.
Old 18th April 2022
  #7
Old 18th April 2022 | Show parent
  #8
Gear Head
 
🎧 15 years
Quote:
40 deg C is 104 Deg F, not 129.2 Deg F.
My apologies - that was a misprint on my part! The tests were, in fact, done at 54Β°C (129.2Β°F). I've since updated my post for future 'bakers'.
Old 4 weeks ago | Show parent
  #9
Lives for gear
 
🎧 10 years
If the backcoat is already falling off, you may be in trouble. I have seen a few tapes where the coatings simply fall off after baking, which is of course unrecoverable. I have only seen this a couple of times out of thousands of tape bakes.

Quote:
Originally Posted by Thomas W. Bethe ➑️
Thanks for the link. The tapes are all in white boxes with the person's name and their contents listed but no mention of the tape # or the manufacture. A few of the tapes are shedding badly with the back coating literally falling off the tape and sitting in the box. One of the tapes is reddish brown but again no label as to what the tape is. According to the owner they were all stored in a "home environment" and all from the early 1980s. It will be an interesting project to say the least.
Old 4 weeks ago | Show parent
  #10
Gear Maniac
 
🎧 5 years
Quote:
Originally Posted by GLouie ➑️
If the backcoat is already falling off, you may be in trouble. I have seen a few tapes where the coatings simply fall off after baking, which is of course unrecoverable. I have only seen this a couple of times out of thousands of tape bakes.
Yes the back coat falling off sounds unusual. In extreme cases a coating doesn't fall off but being stuck to the opposite side of the tape it is ripped off when the tape is unwound from the reel. That possibility is a good reason not to play or even unwind such a tape. Bake it first.

But even if the back coat did come off it wouldn't be a disaster. The recording is not in the backcoat but the oxide.
Old 4 weeks ago | Show parent
  #11
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Thomas W. Bethe's Avatar
 
1 Review written
🎧 15 years
Quote:
Originally Posted by timtape ➑️
Yes the back coat falling off sounds unusual. In extreme cases a coating doesn't fall off but being stuck to the opposite side of the tape it is ripped off when the tape is unwound from the reel. That possibility is a good reason not to play or even unwind such a tape. Bake it first.

But even if the back coat did come off it wouldn't be a disaster. The recording is not in the backcoat but the oxide.
In this case both the backing and the oxide are coming off in the box. I have no idea of how this was stored but...someone other than me must have played it at sometime in the past. I will post a picture of the mess.
I already told the client that certain tapes she dropped off are unplayable.
Thanks for all your help!
Old 4 weeks ago
  #12
Lives for gear
 
🎧 15 years
I've had issues with the coating flaking off where the tapes haven't been baked for long enough or not left for long enough after baking. 12-14 hours at 55 degrees C is normal for 1/4" tapes for me now with longer times for wider tapes. I make sure that the oven is fairly full so that the temperatures ramp up and down slowly. If I don't have enough tapes to fill the oven I stick an old 2" reel of tape into the bottom of the oven to give more thermal mass.

If there are any sections of stripy leader tape then I often find that the coatings stick to the stripes - there must be something about the ink they used.
Old 4 weeks ago | Show parent
  #13
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Thomas W. Bethe's Avatar
 
1 Review written
🎧 15 years
Quote:
Originally Posted by jamesp ➑️
I've had issues with the coating flaking off where the tapes haven't been baked for long enough or not left for long enough after baking. 12-14 hours at 55 degrees C is normal for 1/4" tapes for me now with longer times for wider tapes. I make sure that the oven is fairly full so that the temperatures ramp up and down slowly. If I don't have enough tapes to fill the oven I stick an old 2" reel of tape into the bottom of the oven to give more thermal mass.

If there are any sections of stripy leader tape then I often find that the coatings stick to the stripes - there must be something about the ink they used.
Thanks for the information. I will be starting to bake the tapes tonight. I use a modified food dehydrator with an external temperature control and it works very well. I will follow the procedures and times recommended. Thanks again!!!
Old 4 weeks ago
  #14
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Thomas W. Bethe's Avatar
 
1 Review written
🎧 15 years
Here is what came out of one tape box. It was collected in a vacuum cleaner so there is "some dirt" with it but it is mainly shredded tape particles. Never seen anything quite like this before in all my years of working with tape...
Attached Thumbnails
Just got in 20 R to R tapes for restoration...-tape-residue.jpg  
Old 4 weeks ago
  #15
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Riccardo's Avatar
 
2 Reviews written
🎧 15 years
I keep a vacuum cleaner at hand. I have seen much worse if that helps!
Old 4 weeks ago
  #16
Lives for gear
 
🎧 15 years
I've often seen particles like that coming from baked tapes although rarely that many from a single tape.
Old 1 week ago
  #17
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Thomas W. Bethe's Avatar
 
1 Review written
🎧 15 years
Baking the tapes at 130F for 12 hours and then letting them cool for an additional 12 hours seems to be working well. Of the 20 tapes so far 5 of them are unplayable do to severe oxide shed. The rest are playing fine. The new dehydrator seems to be doing a GREAT job. Glad I got it.

The tapes that are doping the best were recorded at the local conservatory, the ones with the worst oxide shed were recorded in Cincinnati by some remote recording company and those tapes are in terrible condition. A good audio friend of mine looked at the tapes and said he thinks they were using really cheap back coated tapes to save money. It was not worth it...

I will be happy when this is all done. I am beginning to hate back coated tapes.

FWIW
Old 1 week ago
  #18
Gear Maniac
 
🎧 5 years
If after 12 hours a tape showed signs of still sticking let alone shedding, I'd probably bake it for another 12 hours and check it again. If still not right, maybe another 12. Baking isn't a one size fits all.
Old 1 week ago | Show parent
  #19
Here for the gear
 
🎧 10 years
Quote:
Originally Posted by timtape ➑️
If after 12 hours a tape showed signs of still sticking let alone shedding, I'd probably bake it for another 12 hours and check it again. If still not right, maybe another 12. Baking isn't a one size fits all.
Unless of course the problem is a loss of lubricant (very common in Shamrock, Shannon, Gee and some Syncrotape) in which case repeated baking does nothing.
Old 1 week ago | Show parent
  #20
Gear Maniac
 
🎧 5 years
Quote:
Originally Posted by ken long ➑️
Unless of course the problem is a loss of lubricant (very common in Shamrock, Shannon, Gee and some Syncrotape) in which case repeated baking does nothing.
Yes maybe. Thomas said they " needed baking" but I don't recall him saying they were sticky. Just that there was binder falling off and particles in the boxes. If classic SSS you'd expect there to be signs of adhesion between winds when unwinding. Hess speaks of trying cold play and high speed playback with Shamrock tapes.
Old 1 week ago | Show parent
  #21
Here for the gear
 
🎧 10 years
Quote:
Originally Posted by timtape ➑️
Yes maybe.
IME, not maybe! Never found this to be a hydrolysis issue.

Quote:
Hess speaks of trying cold play
Think we discussed this previously. Not practical or particularly effective.

Quote:
and high speed playback with Shamrock tapes.
Having just worked on about 2 dozen of these, this seems to be the least invasive option: double speeds (both sampling and machine speeds) - Removing anything in the path that doesn't need to be there (erase head, record head etc). Then it's just a question of halving the rate in the header. The trade off is the EQ shift.

The other method is lubing the tape as it unwinds but this can introduce other mechanical problems.
Old 1 week ago
  #22
Gear Maniac
 
🎧 5 years
I was agreeing that it may be the Shamrock "loss of lubricant" problem but we can only go on what has been stated. The tapes "needed baking" it was said. Nothing was said specifically about sticking/squealing. Like other comments I dont know what the particles in the tape box signify.
Old 1 week ago
  #23
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Thomas W. Bethe's Avatar
 
1 Review written
🎧 15 years
This is what happened after two 12 hour at 130 F tape baking episodes to this back coated tape. The machine it is on is our "tape winder" and it used to "exercise" and "repack" audio tapes. The tape was recorded in Cincinnati in the 1980s. The manufacturer and tape type are unknown since it was given to us in a "plain white box". That is the oxide and not the back coating. This is the same tape that was shown above ^ in post #14 . I have never in my life seen anything like this and all I can think about is this tape was stored in a very humid place. Learning a lot...by the way this tape was over the 7" reel by about 3/16th of an inch and was "held on" by some gaffer's tape.
Attached Thumbnails
Just got in 20 R to R tapes for restoration...-tape-problem.jpg  
Old 1 week ago | Show parent
  #24
Here for the gear
 
🎧 10 years
Quote:
Originally Posted by timtape ➑️
I was agreeing that it may be the Shamrock "loss of lubricant" problem
I read that as "maybe... repeated baking [on LOL tapes] does nothing." It does do nothing, just to clarify.

The pic above is horrendous.
Old 1 week ago | Show parent
  #25
Gear Maniac
 
🎧 5 years
Quote:
Originally Posted by ken long ➑️
I read that as "maybe... repeated baking [on LOL tapes] does nothing." It does do nothing, just to clarify.
Yes that's how I thought you must have read it, hence my clarification. Obviously baking does nothing in such a case. That was never in question.
Old 1 week ago | Show parent
  #26
Gear Maniac
 
🎧 5 years
Quote:
Originally Posted by Thomas W. Bethe ➑️
This is what happened after two 12 hour at 130 F tape baking episodes to this back coated tape.
Is this the same tape in post 14 where you said "the backing and oxide are coming off in the box." ?

If in the tape box the oxide had already fallen off or was only holding on to the base film weakly, obviously baking would not fix it and may have done more damage by weakening whatever remaining bond the oxide had with the base film.

Some tapes should never be baked. Acetate based tapes should never be baked.

I'm amazed that the reel was allowed to unwind that much. Why not stop the wind the moment the oxide started to peel off?

Trying to find a positive. Hard to know from here but maybe even those fragile sections of 1/4" oxide could still be expertly adhered to a 1/4" tape base and the data transferred.

Quote:
Originally Posted by Thomas W. Bethe ➑️
by the way this tape was over the 7" reel by about 3/16th of an inch and was "held on" by some gaffer's tape.
What was/is the tape pack like? Smooth? Popped strands? Spoking?

Could/can you see through the tape pack if held up to the light?
Old 1 week ago | Show parent
  #27
Here for the gear
 
🎧 10 years
Quote:
Originally Posted by timtape ➑️
Trying to find a positive. Hard to know from here but maybe even those fragile sections of 1/4" oxide could still be expertly adhered to a 1/4" tape base and the data transferred.
Now that's something I'd like to see!
Old 1 week ago | Show parent
  #28
Gear Maniac
 
🎧 5 years
Quote:
Originally Posted by ken long ➑️
Now that's something I'd like to see!
So would the customer, I guess...

Looking again at the photo something looks odd. On the take up reel appears to be tape with the oxide layer intact. Just the lighting perhaps. Or maybe the shedding section is only one section of tape different from the rest of the reel and spliced in. It happens.
Attached Thumbnails
Just got in 20 R to R tapes for restoration...-tape-problem.jpg  
Old 1 week ago | Show parent
  #29
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Thomas W. Bethe's Avatar
 
1 Review written
🎧 15 years
Quote:
Originally Posted by timtape ➑️
So would the customer, I guess...

Looking again at the photo something looks odd. On the take up reel appears to be tape with the oxide layer intact. Just the lighting perhaps. Or maybe the shedding section is only one section of tape different from the rest of the reel and spliced in. It happens.
No the whole reel was shedding both backing and oxide layer. It must be the lighting.
Old 1 week ago | Show parent
  #30
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Thomas W. Bethe's Avatar
 
1 Review written
🎧 15 years
Quote:
Originally Posted by timtape ➑️
Is this the same tape in post 14 where you said "the backing and oxide are coming off in the box." ?

If in the tape box the oxide had already fallen off or was only holding on to the base film weakly, obviously baking would not fix it and may have done more damage by weakening whatever remaining bond the oxide had with the base film.

Some tapes should never be baked. Acetate based tapes should never be baked.

I'm amazed that the reel was allowed to unwind that much. Why not stop the wind the moment the oxide started to peel off?

Trying to find a positive. Hard to know from here but maybe even those fragile sections of 1/4" oxide could still be expertly adhered to a 1/4" tape base and the data transferred.



What was/is the tape pack like? Smooth? Popped strands? Spoking?

Could/can you see through the tape pack if held up to the light?
If you read my post #23 I said it was the same tape. FWIW

I have been in the pro audio field for over 50 years and I know what can be baked and what cannot. This was BACK COATED tape.

If you look at the picture that is exactly what I did. I stopped the spooling as soon as I saw what was happening. What you see on the top of the machine is from the beginning of the tape up until I stopped it. The winder runs at approximately 30 ips so it move a lot of tape in a short time. That is NOT a playback or recording deck and was made into what it is used for from an old dubbing deck. There are no heads in it and no electronics. It is just a deck.

I know it is hard to tell things from a distance but I do know a lot about tapes and tape recorders. You seem to state the obvious at times like I don't know anything. Maybe it is because I ask question in this forum? Anyway thanks very much for your help and suggestions.

Be safe and STAY HEALTHY!
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