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How can I tell if I need to bake an analog tape?
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17th January 2010
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How can I tell if I need to bake an analog tape?

Does anyone know if there is a way to determine if older analog tapes need to be baked or not? Touch? Cotton swab with alcohol? Rub it on a gypsy's palm? … Seriously though, I am hoping there is a way to assess tape to see if baking is needed.

I have some reels of 20-25 year old Ampex 456 (½“x2500’) that I would like to use, blank tape if it is usable plus I have some recorded tracks that I would like to get into my DAW.

The tapes feel okay to the touch but I am reluctant to assume that they are okay to use as-is ….

Any insight is greatly appreciated.
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I'd bet any money they will need baking. 456 is very prone to sticky shed syndrome.

The easiest way to tell is to get them on your machine and slow/library rewind no more than 15 seconds or so. Then examine your tape lifters (assuming they are the static kind) or any part of the assembly that rubs against the tape as it travels.
You should avoid running the tape over your heads if at all possible.

If they need baking you will see a brown goo on your tape lifters. You can also just rewind, then fast forward. The tape will likely squeal as you change direction and run slower than normal, leaving more goo on your machine.

You wouldn't really be able to use them as new, even if you bake them they will turn again in 2-3 weeks.
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Does it taste alright?

Sorry.

Inglewood SoundBarn

But seriously, only certain batches of 456 from the 70's (I think) are prone to shedding. I did get a batch once and it is a royal pain in the ass. Salvage what you can but don't use it for recording if it is the shedding stuff.
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when you put it on your machine and great gobs of crap start coming off on all the heads and guides then you know you should have baked it

Quote:
20-25 year old Ampex 456 (½“x2500’)
456 of this vintage I would bake it first without even trying to play it.

Quote:
blank tape if it is usable plus I have some recorded tracks that I would like to get into my DAW.
baking will make your tape playable for a few days, a week or two at the outside, but eventually it will get gooey again. Good for recovering the old music.

After it reverts to its gooey state, you can bake it again, but obviously using it as blank tape would be impractical.
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There is only one way of finding out: try playing it! Sorry, there is no easy test.

If the tape is "sticky" it will leave a black goo over the tape path which will require careful and thorough cleaning. It may squeal as it plays and it may stall the tape machine in Rewind or Fast Forward. Or any combination of the above. You may not discover it is faulty until way into the reel and then have to rewind it by hand. You cannot just try a few minutes.

Do not assume that if a tape is old it needs baking, that could do more harm. The main reason a tape will require baking is that it was manufactured with a defective batch of binder that will absorb moisture from the air. I'm afraid to tell you that 20-25 year old Ampex 456 is highly likely to be of that type. Most manufacturers got some of the bad binder between 1976 and 1984 which appeared randomly in some of their products, usually the professional ones. It took time for this fault to be noticed so there is a large window. Older tape is usually fine, even if stored in a damp polythene bag and covered in mould, it does not need baking--just leave it exposed to the air at room temperature for about a week.

After baking a tape will reabsorb again so the only point in baking is to recover valuable material recorded on it. It is not advisable to bake a tape to make it usable, because that will only be for a limited period. Sometimes baking makes the tape brittle and sheds oxide so there may only be one chance of playing it. Other times it may seem fine for a year, but eventually it will reabsorb.

More information here:
HINTON INSTRUMENTS: Tape Baking and Recovery
We have recovered quite a few masters that have now been re-released. We had one last year that was on a 12.5" spool and had to be hand wound onto two 10.5"spools before drying. The tape was so sticky that it came off the reel like Sellotape and took three hours of careful spool turning.

Another had been stored with sachets of anhydrous crystals in the box that had absorbed so much moisture that they had dissolved and soaked into the tape and box! After 28 hours of baking the tape was playable for about 10 minutes, it was sucking moisture from the air while playing so the material had to be copied a track at a time with more baking between each.
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17th January 2010
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No ..don't assume it needs baking ..I have tapes from 50's and 60's that are dry and work fine.

Anyway, put a reel up, hit play and within a few seconds you'll know if it needs baking. Tape that needs baking is liquid gooey.
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Quote:
Originally Posted by drp audio View Post
Does anyone know if there is a way to determine if older analog tapes need to be baked or not? Touch? Cotton swab with alcohol? Rub it on a gypsy's palm? … Seriously though, I am hoping there is a way to assess tape to see if baking is needed.

I have some reels of 20-25 year old Ampex 456 (½“x2500’) that I would like to use, blank tape if it is usable plus I have some recorded tracks that I would like to get into my DAW.

Any insight is greatly appreciated.
Here is a list of tape types and years that are typically prone to Sticky-Shed Syndrome:
Tapes with Sticky-Shed Syndrome

"When to Bake a Tape...

There are some important signs that show when a tape needs baking. The typical symptom is squealing when the tape passes the playback head or other fixed parts of a tape player. The squealing is audible directly from the tape and also transmitted electronically through the output of the tape recorder. Continuous use of a squealing tape risks permanently damaging the tape, as oxide is sometimes torn off the tape. This flaking residue can be seen and can feel gummy while still on the tape's surface. There is also a risk of damage to the player. Another symptom is the tape sounding dull and distorted.

Deterioration can happen to any tape, but the problem is more common with audio recording tape manufactured in the USA from the mid 1970's to the early 1980's.

Tapes That Generally Need Baking...

* AMPEX- 406, 407, 456, 457, 499, Grand Master
* 3M- 153, 206, 207, 208, 209, 217, 219, 226, 227, 806, 807, 808, 809, Classic DP, Classic LP, Classic SP, Master and Master SX"
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Hi there, I freelance at a place that specializes in tape transfers and archiving and this is what I've learned

A simple way to look for sticky shed is to carefully unwrap the tape from the reel by hand - it the tape does not fall freely from the reel, it needs baking - with sticky shed on a tape, it will slightly adhere to the layer underneath (in varying degrees depending on the severity of the problem) instead of falling freely from the reel.

A tape that is baked is good for about a month then it will need rebaking
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18th January 2010
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Quote:
Originally Posted by vernier View Post
No ..don't assume it needs baking ..I have tapes from 50's and 60's that are dry and work fine.
.
yes - tapes from the 50's and 60's are rarely a problem

the OP was asking about 456 from the 80's which in my experiences is always a problem
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What are the directions for backing tape anyway?
Please share.
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the "squeal" of sticky tape shows particularly well when hitting "stop" from a wind mode.
And it isn't limited to certain batches from the 70's. It is pretty consistent with 456 and recently I've seen it on here to for immune 996.
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Quote:
Originally Posted by Rednose View Post
What are the directions for backing tape anyway?
Please share.
You take your tape to a pro with a pharmaceutical grade oven!
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19th January 2010
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Quote:
Originally Posted by Rednose View Post
What are the directions for backing tape anyway?
Please share.
Farberware convection oven. 130 degrees F. 8-10 hours.
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19th January 2010
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Quote:
Originally Posted by joeq View Post
yes - tapes from the 50's and 60's are rarely a problem

the OP was asking about 456 from the 80's which in my experiences is always a problem
So far I've only had problems with some 3M 226.
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Quote:
Originally Posted by vernier View Post
So far I've only had problems with some 3M 226.
Vernier,
I think you are living in an alternate universe!
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19th January 2010
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Thanks for all the great help, I appreciate it. Nice to hear from people with actual experience.

bigdoghat - love the name, great info, +1 on the freefalling tape idea
joeq - we think alike I think, thanks for posting
soundbarnfool - tastes like chicken, free range of course like the ol' days

Question, will it destroy a tape to bake it if it is not gooey? Graham Hinton suggested damage potential but I'm leaning towards joeq's advice, just bake it and don't ask questions! As I research tape baking on GS and online in general it seems like bake temperatures are consistent but there are great variances in bake time (3-8 hrs), leading me to believe that baking too much is less of a concern, leading me to believe that baking a tape which is already dry may not harm it(?). Does this reasoning make sense?

I’ll forget about using old tapes for new material. I’m happy just to capture some old tracks into a DAW and make sure the tape machine is working fine at this point. Fortunately the tapes in question are my own material and I run 30-60 seconds of blank tape before using a tape to record. At 15ips this gives me some tape to experiment with before I hit program material. I will try a pre-check by running some tape between my thumb and a screwdriver shaft (shiny, round and cleaned with tape head cleaner). I’m thinking that this will simulate a tape guide or the like …(?)

Here’s my plan unless I get convinced that it is okay to bake a tape without even running it simply to ensure that it is dry before use.

1) Spin reel with hands to see if tape falls freely from reel. Just curious about this. Then I’ll …
2) Slide 3-4 feet of tape end against a clean screwdriver shaft and check for tape “goop” (simulated metal tape guide …?). If there is evidence then baking is needed then I will bake. If not then I will …
3) Load tape and run over tape lifters for about 10 seconds then check for tape goop. If all is clean then I will …
4) Load the tape onto reels and try a pass over the heads with monitoring all set, and I’ll be watching and listening VERY close for problems and I’ll be ready to shut it down immediately if needed. Stop and check heads after a few minutes of playback.

If I need to bake I will bake for 6-8 hours at 130 F degrees. I will likely build my own cardboard box oven with a light bulb and small fan if I can get a constant enough temperature using various wattage bulbs and cracking the box cover if needed. I will use a wood block or something to set the reel of tape on so it doesn‘t sit on the “oven“ floor. Baking tapes seems not unlike making jerky, low temps for long periods of time, slowly driving all moisture out. I do not own a convection oven or a dehydrator.

Still learning, post more if you have knowledge and experience to share ….
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20th January 2010
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Last edited by exgato; 20th January 2010 at 12:13 AM.. Reason: typo
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Quote:
Originally Posted by drp audio View Post
Fortunately the tapes in question are my own material and I run 30-60 seconds of blank tape before using a tape to record. At 15ips this gives me some tape to experiment with before I hit program material.
If you have that blank tape available the way I check is to do a quick FF or RW (so the lifters are out) and, without hitting stop, reverse the FF/RW to spin the tape off the machine. Several things can happen.
1. Everything goes smooth and quick and no oxide is found on the lifters....the tape doesn't need to be baked.
2. The tape slows a little (or not) squeals (or not) and the lifters show an accumulation of oxide......needs baking.
3. The tape stops dead in its tracks and leaves massive amounts of oxide on the lifters........needs baking and a few prayers. Also needs to be routed directly between the reel motors and spooled off the machine.

Not so sure how conclusive the screwdriver test is if you haven't encountered this kind of tape before but the machine test has always told me what I need to know.....obviously you need to do this on an area of the tape that does not have any valuable program recorded on it!

Also, I have baked hundreds of tapes without any catastrophes yet. Some were not gooey but baked anyway and were not damaged.
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20th January 2010
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Quote:
Originally Posted by exgato View Post
I am convinced the people who designed the Snackmaster had its alternative use as a tape baker in mind! The round trays fit 15" reels to a T, and the central heating unit fits right in the hub holes of the reels.

My older model Snackmaster runs a little hot and does not have a temperature control, so I plug it into a Variac and use a remote thermometer to keep an eye on the temps.

I made a spacer out of some vinyl molding so the bottom shelf can have 7" reels lying down on the bottom 'floor' without touching the heater.
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Stick a fork in it and if it comes out gooey...
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WHITE goo

Since this is turning into a decent, informative thread, I would suggest someone adding some information about the OTHER tape problem, bad lube.

I am not an expert on this, so maybe someone can chime in. From my experience, if the GOO IS DARK it is sticky shed. if the GOO IS LIGHT COLORED it is the lubrication coming off the tape, and that is a whole other problem. Those tapes should not be baked.

I have seen many reels of 468 and 469 that were not stored well and had that problem.
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Quote:
Originally Posted by TRJanuary View Post
Since this is turning into a decent, informative thread, I would suggest someone adding some information about the OTHER tape problem, bad lube.
Excellent point. I've seen the "lack of lube" problem and it is a royal pain.
Here is one discussion that merits reading:
Relubricating Analog Tapes
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The gooey build-up largely comes from the BINDER used to "glue" the iron oxide onto the mylar backing breaking down chemically and absorbing moisture from the air.
In essence, the BINDER becomes a wet substance again like it was when it was applied to the tape.

Baking "dries out" the binder again, but once the chemical make-up of the binder is altered due to age, heat or other environmental issues it will again start to absorb moisture.
This is why a baked tape will get gooey again.
The binder has broken down chemically which makes it prone to absorb moisture.
It is all an un-anticipated result of the chemical make-up of the binder material.

I have never heard the "dark colored goo" versus "light colored goo" explanation before.
There also is no "lubrication" material that I know of.

Mostly, the OP was asking about baking tape in order to use it as a recording medium.
If you read what I said above you realize that baking is only a temporary solution.
You could use the baked tape maybe to record onto and then transfer back to a digital medium, but once the binder has broken down chemically the tape is not very good for long term storage.
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Quote:
Originally Posted by TRJanuary View Post
Since this is turning into a decent, informative thread, I would suggest someone adding some information about the OTHER tape problem, bad lube.

I am not an expert on this, so maybe someone can chime in. From my experience, if the GOO IS DARK it is sticky shed. if the GOO IS LIGHT COLORED it is the lubrication coming off the tape, and that is a whole other problem. Those tapes should not be baked.

I have seen many reels of 468 and 469 that were not stored well and had that problem.
I've seen tapes that suffer from loss of lubricant at work quite a few times and it does look white - a kind of a chalky white - my boss tells me that this is super bad for the tape path and the entire tape path needs to be cleaned immediately if any lubricant is visible. Btw, I'm no expert either, just passing on the bits of knowledge I've picked up and remember. I'm more of an op, I don't make any decisions re the condition of a tape and what needs to be done with it prior to transferring but I'm always asking questions re the various issues with the various tape types since it's kind of fascinating and his wealth of knowledge is extraordinary.
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Quote:
Originally Posted by drp audio View Post

Question, will it destroy a tape to bake it if it is not gooey? Graham Hinton suggested damage potential but I'm leaning towards joeq's advice, just bake it and don't ask questions! As I research tape baking on GS and online in general it seems like bake temperatures are consistent but there are great variances in bake time (3-8 hrs), leading me to believe that baking too much is less of a concern, leading me to believe that baking a tape which is already dry may not harm it(?). Does this reasoning make sense?
Generally not. Unless you have an acetate tape. Baking would completely destroy an acetate tape.

The easiest way to tell an acetate tape that I know of is to hold it up to the light. If it is translucent (i.e. you see light through it) then you shouldn't, or need to, bake it. Generally acetate pre-dates the bad formulations by many years.

Tape, like meat, is better cooked slow and low. So 49 C for 24 hours is better than 4 hours at 60.

I've recently had much luck dehydrating tapes, using a domestic dehydrator. It is much gentler on splices (not making the glue melt all over the tape) and the tape in general.
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20th January 2010
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Quote:
Originally Posted by drp audio View Post
Question, will it destroy a tape to bake it if it is not gooey? Graham Hinton suggested damage potential but I'm leaning towards joeq's advice, just bake it and don't ask questions! As I research tape baking on GS and online in general it seems like bake temperatures are consistent but there are great variances in bake time (3-8 hrs), leading me to believe that baking too much is less of a concern, leading me to believe that baking a tape which is already dry may not harm it(?). Does this reasoning make sense?
No. You cannot unbake a tape. If the material on it is important proceed with caution.

Quote:
I’ll forget about using old tapes for new material. I’m happy just to capture some old tracks into a DAW and make sure the tape machine is working fine at this point. Fortunately the tapes in question are my own material and I run 30-60 seconds of blank tape before using a tape to record. At 15ips this gives me some tape to experiment with before I hit program material. I will try a pre-check by running some tape between my thumb and a screwdriver shaft (shiny, round and cleaned with tape head cleaner). I’m thinking that this will simulate a tape guide or the like …(?)
Sometimes you can play for twenty minutes with no indication that a tape is sticky. Until you try to rewind and the motors stall.
Your proposed test will only show the extremely bad cases.

Quote:
Here’s my plan unless I get convinced that it is okay to bake a tape without even running it simply to ensure that it is dry before use.

1) Spin reel with hands to see if tape falls freely from reel. Just curious about this. Then I’ll …
2) Slide 3-4 feet of tape end against a clean screwdriver shaft and check for tape “goop” (simulated metal tape guide …?). If there is evidence then baking is needed then I will bake. If not then I will …
3) Load tape and run over tape lifters for about 10 seconds then check for tape goop. If all is clean then I will …
4) Load the tape onto reels and try a pass over the heads with monitoring all set, and I’ll be watching and listening VERY close for problems and I’ll be ready to shut it down immediately if needed. Stop and check heads after a few minutes of playback.

If I need to bake I will bake for 6-8 hours at 130 F degrees.
Too short a sample, too long a time and a bit too high a temperature. You only want to remove the moisture that has incorrectly been absorbed into the binder, not the moisture that was there before that.

I would try to play the tape to assess its condition and then, if necessary, bake for 2 hours at 120 F. Then reassess and judge how much further it needs by the change. It's something you have to get a feel for and you'll only get that through trial and error. You just don't want to make the errors on anything really important. So it depends on the consequences of losing what is recorded on the tape, once it's gone it's lost for good. Too much caution and you have to clean the tape path again.

The state of sticky tapes can vary greatly, it depends on how much moisture has been absorbed over the past 25+ years and the storage conditions. I find that once a tape has gone sticky that the black goo is coming mainly from the matt backing which is black and will build up on rollers that touch that side of the tape. After baking, there tends to be more oxide shed on the heads, which is brown deposits. I have had a few cases where the oxide has shed in serious amounts on the first playing after baking, it is quite a disturbing feeling watching pyramids of rust grow knowing that it contains the recording.

You are dealing with a thin strip of plastic that has dust stuck to it on both sides with a polyurethane "binder" and it is the latter that has become runny. It depends how much it has crept over time. Overbaking may bake together the backing from one side with the oxide on the next turn and then one side will be torn off the tape as it unspools.
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20th January 2010
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Quote:
Originally Posted by Graham Hinton View Post
Overbaking may bake together the backing from one side with the oxide on the next turn and then one side will be torn off the tape as it unspools.
Interesting you say that Graham. Have you ever found that baking causes this problem?

We have found "adhesion to adjacent layer" to be a problem prior to baking, and baking made no difference.
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Quote:
Originally Posted by dbbubba View Post
The gooey build-up largely comes from the BINDER used to "glue" the iron oxide onto the mylar backing breaking down chemically and absorbing moisture from the air.
In essence, the BINDER becomes a wet substance again like it was when it was applied to the tape.

Baking "dries out" the binder again, but once the chemical make-up of the binder is altered due to age, heat or other environmental issues it will again start to absorb moisture.
This is why a baked tape will get gooey again.
The binder has broken down chemically which makes it prone to absorb moisture.
It is all an un-anticipated result of the chemical make-up of the binder material.
Not quite. Most of the sticky tape found was not right when it was manufactured. A bad batch of binder contained the wrong mixture of chemicals which managed to pass the quality control by still averaging correctly. One of the mixture is hygroscopic and there was a higher ratio of this which should not have been there.

I believe that the binder was manufactured by Dow Corning and supplied to most tape manufacturers, so they all got some at some point. It took years before the first problems showed, so there was a window of time during which they continued manufacturing the bad stuff.

When the problem was understood the quality checks were changed so that it would not happen again. That is why tape before and after this period is OK, but anything
within it is suspect.
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Quote:
Originally Posted by Graham Hinton View Post
Not quite. Most of the sticky tape found was not right when it was manufactured. A bad batch of binder contained the wrong mixture of chemicals which managed to pass the quality control by still averaging correctly. One of the mixture is hygroscopic and there was a higher ratio of this which should not have been there.

I believe that the binder was manufactured by Dow Corning and supplied to most tape manufacturers, so they all got some at some point. It took years before the first problems showed, so there was a window of time during which they continued manufacturing the bad stuff.

When the problem was understood the quality checks were changed so that it would not happen again. That is why tape before and after this period is OK, but anything
within it is suspect.
Not quite what?

You are saying the same thing I am saying.
You are telling me what I said is wrong and then re-stating the same concept using terms like "hygroscopic."
I chose the words I did in order to make everything be understandable to anyone who read the text.
I don't need to be corrected.

I have been using tapes like 456 (a big offender) since they were first introduced in the late '70s.
I can vividly recall when sticky tapes started to show up in the mid to late '80s.
Most of the bad tapes manufactured by Ampex were not from the original batches in the early years of 456 and yes, they did eventually correct the problem.... to a degree.

I still have a lot of 2" 456 stock that was manufactured between the time of the introduction of 456 until the early '90s ('93 / '94.)
I have transferred almost all of it to digital form and I know what tapes need baking and what it takes to bake tapes.
Ampex supplied technical papers on the subject in the early '90s when the problem started getting really bad.

If you were using a lot of tape in that period of time you certainly know the story.
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