Audio Tape Deterioration

[W1RKW]

I found an old audio tape that a family member recorded of a family gathering back in 1967. I didn't know what was on this tape until I loaded it up into the TEAC.  Imagine my astonishment and surprise hearing voices of relatives who have been deceased for 2, 3 or more decades. I had no idea that I was in possession of this tape.

I had difficulty running the tape as the tape seemed to be spliced in several places from my uncle who made the tape and several splices broke.  Also the tape was brittle and broke in many other places as it was playing.  I managed to get it all spliced in the places where splices broke and where the tape just snapped.  Eventually I managed to get it tranferred to digital media using the PC for longer term preservation.

This all leads up to this question.  I know over time acetate will get brittle but one thing that I noticed when I  was trying to keep it in one piece the oxide seemed to be disappearing in places along the length of the tape and most of it was on one edge of the tape. Fortunately, it wasn't on the recorded track. The oxide wasn't simply flaking off but it seemd to be dissolving and evaporating into thin air.  There weren't any flakes in the box that it was in.  And I've had this tape unknowingly for a minimum of 25 years and it's never been out of it's cardboard box during that time frame.  So I'm curious is it possible for the oxide to simply evaporate or something to eat it?  Now that I've run this tape through my R to R will it contaminate other tapes if there's some sort of tape virus on the tape heads?

[Glenn NY4NC]

Hi Bob,

Iron oxide doesn't evaporate...

What normally happens with old tapes is the Iron Oxide flakes off because the adhesive that bonds it to the backing breaks down over time. Was there oxide dust in the box?

One thing I would be concerned with... when is the last time you de-magged the heads on your Reel to reel? ..The magnetic field on old tapes will get weaker with time. If your heads are not de-magged, they may be actually erasing the tape to a degree... obviously not what you want!. That's the only "contamination" you have to worry about. Of course cleaning the heads, pinch roller and capstan will help to baby the already delicate oxide layer...

Hope that helps..

[W5AMI]

Bob,

That is really neat!  Talk about a blast from the past...

The oxide won't evaporate, nor would it likely break down into a lesser form.  I agree with Glenn, there is likely fine dust in the box a lot of which could have just _poofed_ out when you opened the tape container due to suction. 

Anyway, glad you were able to transfer it to another media.

[WA3VJB]

Bob,

Are you sure it's acetate? Here's a quick test, hold the reel up to a lamp, broadside toward you. If light gets through the layers it's acetate.  Sometimes the oxide will come off the acetate in sections and stick to the next layer. It may also have shed itself while going past the tape guides in your Teac somewhere, or even stuck to old splicing tape where the glue has failed years later.

I recently spooled into the trash can four, brand new reels of audiotape acetate, 1.5 mil 1200 foot on a 7" reel. The heat got to it so bad that the tape, when you unwrapped a few feet and  looked at it, curled up on the edges in a random fashion. It otherwise was perfectly layered as originally produced. You could not rewind it once the tension was lost. Moreover, it wouldn't lay flat on the heads, so be glad yours wasn't that bad off.

Yes, it's very brittle regardless, and the best way to handle it is to NOT use the brakes on the tape machine, instead using a technique known as dynamic braking. If you're in fast forward, hit rewind and allow the torque of the motor to more gently counteract the direction its been going. Then, when it's almost at a standstill, hit stop or use your finger to gently rub it down to a standstill.  Practice on some non-critical tape.  This presumes you've got a solenoid operated transport, not the mechanical lever type.

[W1RKW]

Well I'm glad my tapes don't have AIDS and oxides don't disappear by evaporation or whatever. 

I ran some of my other reel tapes through the machine and they seem to be in very good condition still.  No drop outs or missing oxide.  I guess my Uncle, when he made this tape probably used a mediocre brand or maybe it just wasn't stored properly before it ended up in my collection.

I found it interesting that the tape with my family members exhibited this malady and yet there was no evidence in the box.  Paul (VJB) is probably right about the oxide sticking to the back side of the acetate.  That's probably what has happened so I won't worry about that particular tape as I got it on disc now. The important thing is I caught it and was able to preserve the recording. Whew!

I went out and bought a box of CD-R's today.  I'm going to make this find a Christmas present to all my relatives.  Most of them do have computers and CD players so  I think it'll knock their socks off when they hear it. It knocked my socks off. This should be interesting because my mothers side of the family is italian and they're very emotional.  I don't know what I may be getting into.  Wish me luck. 

[W2JBL]

 i have hundreds of hours of very rare classic jazz performances on reel to reel, and the tape i used- either Ampex 256 or 356 "Grand master" and Ampex 640 (which i think is acetate)  is failing in various ways after 30 or so years. the best source  of info on dealing with this problem i know of is Nick KG2IR. he helped me a ton with advice on the Ampex Grand Master tapes... and as Paul said- watch the brakes on the machine and be real gentle with the older acetate tapes. it's awful scary stuff to watch personal recordings and "unissued" performances crumble and flake as you try to save them. 

[WA3VJB]

Bob,
I'd recommend using wav files at 44.1 so that your relatives may also play the CDRs in home CD players and dashboard units. This sample rate and uncompressed file is compatible with most conventional CD players too. And with 700MB per disc, it's hard to reach capacity on one of them even with the largest of audio files.  Further, you might want to make sure you are recording in MONO rather than stereo. Most recording software defaults to stereo and that's a waste of file size if the master is mono any way. When played back, it automatically hits both playback channels on a computer and a CD player.

[John Holotko]

Keep  in mind that  in addition to the oxide coating the "celluloid" substrate  (in this case cellulose acetate) will also deteriorate with age. And it may deteriorate faster in an airtight container  due to build up of acetic acid vapours. Moisture will also catalyze the deterioration of cellulose acetate.  The deterioration of cellulose acetate is almost exactly like the deterioration of cellulose nitrate minus the extreme flammability factor. Signs of cellulose acetate deterioration are yellowing, curling, brittleness, and sometimes an acetic (vinegar) like smell.   
For minimal deterioraton of the acetate substrate keep the tape an a non airtight box, keep it in a cool dry location. With proper care the "cellulose" based plastics can last a while.

I'm not too sure about mylar tapes but I think mylar has it's own set of deterioration charachteristics and, much like celluloid, it does go bad.

[W1RKW]

Bob,
I'd recommend using wav files at 44.1 so that your relatives may also play the CDRs in home CD players and dashboard units. This sample rate and uncompressed file is compatible with most conventional CD players too. And with 700MB per disc, it's hard to reach capacity on one of them even with the largest of audio files.  Further, you might want to make sure you are recording in MONO rather than stereo. Most recording software defaults to stereo and that's a waste of file size if the master is mono any way. When played back, it automatically hits both playback channels on a computer and a CD player.

Hi Paul,
Thanks for the tips but beat you to it so to speak.  I already burned the discs at 44.1kHz. 44.1 is a good sample rate for capturing full fidelity. They all work good in an audio CD player and on a computer so problem for anyone to play them. 

The original tape surprisingly still had excellent sound quality. There were some dropouts here-and-there where the oxide loss was significant but they showed up as low frequency thumps in a few places but otherwise hardly noticeable as they were on the farside of the tracks and the tape speed was set at 7.5ips.  Information loss was at a minimum or none existant pretty much.

The tape was recorded in stereo.  I could tell that the mics were separated fairly well as there is definitely a left and right to the recording (people on the left and people on the right).  So I kept the stereo mode to keep the spatial effect.  Even though the stereo mode uses up more memory I had plenty of room left over on the disc.  The overall recording time is about 31 minutes so I used (if I remember correctly) about 320MB of disc space.  Thanks.
Bob

[WA3VJB]

Wow, Bob, stereo tape format, mics placed properly, somebody had some gear and the knowhow.
Any clues what the machine was and who you have to thank for making the recording ?




One other point, if you came in at 320MB, then you had enough room on that CDR to actually record the set TWICE.
I am not yet convinced about the archival properties of ink-based CDs (compared to punched foil commercial CDs). So you have the capacity to provide a backup copy that might survive a hit on the other passage, same disc.

As for tape deterioration, here's one of the best disertations I've read about various tape problems.
Worth reading.

http://www.tangible-technology.com/tape/baking1.html

[W1RKW]

Hi Paul,

Many of my relatives on my mothers side of the family have had some sort of involvement in radio and the entertainment industry. The ones in radio didn't have involvement in a technical nature but more of a production nature. My Uncle who recorded the tape didn't work in the radio production area. He was in the medical field but loved to play with audio.  He was into audio as a hobby and recording.  He was musician too.  I remember as a young JN (were talking 40 years ago) his home recording studio, he had electronic equipment and musical instruments in the basement and he would record people.  He was quite good at it from what I hear from the current living relatives and enjoyed his hobby. So he knew something about.  I don't believe it was "slapped" together judging from the sound quality.  I'd also be interested in knowing what he used for a tape machine and microphones.  The sound quality is outstanding minus the occasional dropout caused by the missing oxide layer in places. As far as the equipment and machine he used, unfortunately I'm clueless in that area. I think I was 6 or 7 years old then.

I have the audio on CD and I have some harddrives kicking around that I can make into digitally magnetic recordings as well.  I agree.  I don't know what the life expetancy of a CD-R is.  Only time will tell I guess.

Thanks for the link. It made for interesting reading.  I'm not so sure I want to bake a tape just yet though it sounds like it could work.

[K3ZS]

I had some reel to reel tapes I made from the 60's.  My brother and I played in rock bands.  Also had some with relatives and also my kids as they grew up.  I fixed up my old Lafayette reel to reel, and when recordable CD's and computers became affordable, I started to transfer it all onto CD's.  I noticed that the heads were caked with oxide after one pass.  I cleaned the heads after each side was played.  I think most 1200 ft reels were acetate but the 1800 and 2400 were mainly mylar.  They tend to stretch and not break like the acetate.  Years ago I put our old 8mm film movies onto VHS.  I have now put those tapes onto DVD.  I copy all camcorder movies I make onto the computer and DVD so that 30 years from now my decendants won't be breaking tapes.

[Glenn NY4NC]

I've also played in rock bands and recorded on various funky old reel-to-reels over the years.. Lafayette, Sony and Wolensack machines... I have some reels I've been saving for transfer to digital but I need to get a hold of a deck where I can move the play head up and down. The machine the recordings were made on wasn't aligned so the tracks are shifted on the tapes. Two track recordings on both sides of the tapes so you hear some "reverse" music 

[Glenn NY4NC]

Look..... Dick likes Roberts!!