Corey Bailey
Audio Engineering
USEFUL INFORMATION
LUBRICATING POLYESTER AUDIO TAPE
Disclaimer
Neither I or my company has profited in any way from the people or
organizations mentioned in this article or elsewhere on this site. The opinions
expressed herein are mine alone and do not reflect upon the people or
organizations mentioned in this article.
Some background
First of all, I want to be very clear; In this article, I am talking about polyester
base audio tape only. This would exclude all acetate base audio tape. Acetate
base audio tape, most likely, will not benefit from the processes described in this
article. In fact, you can possibly harm or do permanent damage to acetate base
audio tape by lubricating it using the material and the procedures described
herein. Acetate base magnetic film is another animal entirely. The acetate base
used in magnetic film is much thicker (about 5 mils in the US, compared to
acetate base audio tape which is about 1.5 mils thick) and the oxide layer applied
to film is much thicker as well.
I began researching lubricants when I was the Director of Sound at MGM
Studios. This was 1993 and our Sound Transfer room was coming across some
Reel-To-Reel audio tapes and magnetic film that needed help to play properly.
Some wouldn’t play at all. Most of the acetate base magnetic film suffered from a
condition known as “Vinegar Syndrome”, but a small percentage had other
problems that affected it’s playability. The magnetic film that fell into this category
usually appeared to have a translucent white ‘milky’ substance on the oxide. The
audio tape, on the other hand, was suffering from the oxide being soft and
sometimes sticky. I talked to everyone that I could think of and all of those that
were suggested. From Dr. Andrew Lazare of the National Media Labs, I learned
the term Binder Hydrolysis and of the relatively short life span of magnetic media
in general. I also learned of the patent filing by AMPEX Corp. regarding the
baking of polyester audio tapes. The patent filing by AMPEX however, didn’t
address the issues with magnetic film that we had observed. John Bonner, the
Chief Engineer of Warner Bros. Studios in West Hollywood CA, was
experimenting with the use of baby powder on magnetic film. Although talcum
powder did help, it was messy and would clog the play head every few hundred
feet or so which would require numerous stops and starts to get through a reel of
magnetic film. I decided to experiment with lubricating the oxide of the media that
was suffering from playability issues. I used to say that I had tried everything
from Alcohol to Xycote (pronounced ‘Zee-cote’). Over the years, I did find a few
chemicals that worked. Alcohol being one of them and Marie O’Connell seems
to have perfected the system using alcohol for audio tape playback. Some others
that appeared to have positive effects were Decamethylcyclopentasiloxane (D5),
Filmguard, Jojoba oil, several silicone based lubricants, Last tape preservative
(Tape Last) and Xycote which, is no longer made. My favorites were alcohol, D5,
Filmguard and Last tape preservative. Walter Davies, the inventor of Tape Last,
introduced me to that product. Regarding the chemicals tried, I have no idea of
their reactions with the chemistry of magnetic media or the long term affects,
although Walt Davies assured me that Tape Last had no adverse effects on any
kind of audio tape. In fact, he noted that Tape Last would enhance the shelf life of
audio tape when treated. I do use alcohol (99%) to treat mold on polyester audio
tapes and I have observed no ill effects from doing so. Filmguard was developed
for motion picture film and works well on magnetic media. However, Filmguard
leaves an oily residue. Last tape preservative is the only one that is made
specifically for audio tape, evaporates quickly (like alcohol and D5) and the only
one to address storage of the media after its use. The only storage history that I
have on Last tape preservative is from some of my own tapes that I treated in
1998 and they show no adverse signs from having been treated. Those tapes
have been stored in a closet on an upper shelf at room temperature. Recently, I
revisited those tapes and made higher resolution transfers. I was pleasantly
surprised to find that the tapes that should be suffering from Sticky Shed
Syndrome and were treated with Tape Last, had fared very well. I simply re-
treated them and they played without having to be baked. The only downside to
Last tape preservative, that I know of, is that it is expensive. Particularly in the
manner that I use it.
Assessing a polyester base reel of tape for Binder Hydrolysis
The first thing you will need to do is determine if the tape is suffering from Binder
Hydrolysis (Sticky Shed Syndrome). This subject is also covered in my article:
“BAKING AUDIO TAPE”
The first thing I do with 7" reels (and smaller) is to insert a pencil into spindle hole
and un-spool a few layers by hand. The tape should un-spool freely. This will tell
you if the layers have the tendency to stick together. If you are dealing with a 10-
1/2" (NAB Hub) reel, you will, most likely, have to mount the reel on the tape
deck. Hopefully, the reel brakes on the tape deck will be disengaged, allowing for
easy un-spooling of the tape. I have a couple of TEAC (Brand) NAB hub
adapters (TEAC Part # TZ-612) that have a metal flange at the base which
allows them to mount to an NAB hub off the tape deck. Then, I can use a pencil
threaded through the spindle hole to un-spool a few layers of tape the same as
smaller reels.
If you are concerned about the tape being on the floor, use a clean empty bucket
or wastebasket to catch the tape as you un-spool it. If you do have to mount the
reel on your tape deck, you can use the other reel to take up the slack. When I
check audio tape reels on a tape deck, I will thread the tape directly from one
reel to the other, avoiding the rest of the transport entirely and use both hands to
rotate the reels which gives a better feel for the un-spooling process.
Once you have convinced yourself that layer-to-layer adhesion is not a problem
for the first few wraps, back-wind the tape onto the reel, mount the reel on your
tape deck, and attach about 4 feet of leader to the head end of the tape. The type
of leader (Paper or Plastic) is a matter of individual preference however, non
acidic paper leader is the only one considered to be archival quality. Leader has
several benefits: It allows for thread-up and run-up to speed on a transport
before the beginning of the tape to be transferred passes across the play head.
Consumer decks tend to have shorter tape paths and some were quite good at
recording modulation to the very end of the tape. Leader also keeps the end of
the tape protected at the outer edge of the reel and protects the tape from the
unevenness of slotted hubs at the center of the reel. Eventually, leader will be
applied to both ends of the tape. Having leader at both ends of the tape allows
for the transfer of the entire tape, end-to-end.
Know that sometimes layer-to-layer adhesion won’t rear it’s ugly head until you
are at the last few wraps near the end of the supply reel. This problem most often
occurs on reels with smaller center hubs (5” Reels, 7” Reels, etc.) which is why
you need to pay attention to how the tape comes off of the supply reel until the
very end.
If, you suspect that layer-to-layer adhesion is present, STOP and consult a
professional. Solving the layer-to-layer adhesion can be tricky and remediation is
best done by someone who knows how to deal with the problem. Often, baking
(done properly) is the answer. If any of the oxide has come off and stuck to the
back of the adjacent layer, it's ‘game over’ for that section of audio tape.
Once leader is attached to the outer edge of the tape, with the tape threaded up,
play into the tape for about 30 seconds. Stop the tape deck and disable the
transport (As though you are going to edit the tape). With the tape deck in STOP
mode and the tape threaded up, rotate the reels back and forth by hand. There
should be no resistance except for the reel brakes. No tendency for the tape to
stick to any of the stationary parts of the tape path. Now, pull the tape away from
the transport and observe all of the stationary parts of the transport (heads,
guides, idler arms, etc.). There should be NO evidence of any build-up on any of
the stationary components. With the tape pulled away from the transport, clean
everything that comes in contact with the tape. Use the purest alcohol you can
find. Medical grade alcohol is best, if you can get it. Isopropyl alcohol can be
found that is 99% pure (or greater). Rubbing alcohol that you get at the drug
store usually contains a certain percentage of water and any kind of water is
generally not good for the tape or the tape deck.
Inspect the Q-Tips or cloth that you used for any oxide residue. Presuming that
you have a very clean tape path, play the tape for about 30 seconds again. While
the tape plays, observe how it comes off the supply reel. There should be no
tendency for the tape to stick to an adjacent layer. Listen to the tape while it is
playing past the heads (put your ear up close to the head stack). There should be
no squealing or any suspicious sounds of any kind. Stop after 30 seconds or so,
rotate the reels back and forth by hand (again) to check for any signs of sticktion.
Pull the tape away from the transport and inspect all of the stationary surfaces
(heads, guides, idler arms, etc.) for any sign of oxide deposit. Clean the entire
tape path again and yes, inspect the Q-Tips or cloth that you used for any oxide.
Some discoloration of the Q-Tip is normal. Particularly after cleaning the pinch
roller(s). By now, you have played about a minute or more of the tape and should
not have observed anything out of the ordinary. It is at this point that I will back-
wind the tape to the beginning and lubricate the entire length of the tape. When I
have finished with the lubricating process, I will attach a leader to the end of the
tape and I am ready to begin the transfer after a rigorous cleaning and inspection
of the entire tape path. I will often transfer side B first to avoid the unnecessary
rewinding of the tape even though, on my particular tape deck, the tape only
comes in contact with ball bearing surfaces for any operation other than playing
the tape. If you are not using a lubricant, you can simply spool the tape from one
reel to the other (carefully) and attach a tail leader.
The tape deck that I use for this process (An Otari MTR-15) has been modified
so that the tape itself only comes in contact with rotating bearing surfaces in any
mode other than play. Even the tape lifters have been sleeved so that the
sleeves act as rotating bearings. I will only use the Fast-Forward/Rewind
functions to position the tape prior to transfer. Fast-Forward and Rewind
functions are accomplished using the ‘shuttle’ mode with the tape threaded
around a reversing idler, away from any stationary parts of the transport. Know
that some tape decks, such as the Studer 80 series, are designed with only
rotating bearing surfaces that come in contact with the tape for all operating
modes.
Lubricating analog audio tape
Once you have determined that the tape is not suffering from any kind of binder
hydrolysis, you can move on to the lubrication process. Using rubber gloves or
food prep plastic gloves (They’re much cheaper), Fold a 4”X4” piece of Texwipe®
and wet both sides thoroughly with lubricant. I use Texwipes because they don’t
shed (known as lint free). You can also use Pellon® (available at a yardage
store) or any cloth that won’t shed lint onto the oxide or backing. Place the cloth
so that it covers both sides of the tape. (Fig. 1)
Fig. 1
I use the ‘shuttle mode’ on my tape deck for this process. If your tape deck does
not have a shuttle mode, you can simply bypass the head stack and shuttle the
tape directly from one reel to the other, lubricating the tape in the process. (Fig.
2) You will need to tape one of the idler arms so that the tape deck transport is in
the ON position (Also Fig. 2). Using the play mode to turn the reels will probably
be the safest. Your fingers, holding the cloth, will determine the hold-back tension
during the lubrication process. This is a learned operation so I would suggest
some practice if you are going to use this method. Using a non-shed fabric will
not harm the tape while you become practiced. I would recommend practicing on
a section of blank tape if possible. You can also use an 8MM film editing machine
if you have one. Using an 8MM editing machine, you would simply thread the
tape directly between reels, avoiding the editing assembly entirely. Same goes
for the practice advice since one hand will be cranking the reels.
Fig. 2
For all mechanisms
While shuttling the tape, periodically apply more lubricant to the cloth (tape oxide
side) using an eye dropper or a syringe designed to apply liquids (Not a medical
syringe with a sharp needle!). As to how often to apply more lubricant, it’s all a
learning process and it depends on the speed of the tape passing through the
cloth or by the applicator. I would apply a drop of lubricant every couple of
seconds with the tape traveling at shuttle speed (about 3-5 times play speed).
Obviously, the faster the tape speed, the more often lubricant will need to be
applied. Since lubricating the tape using this process takes two hands, one will
need to stop and apply more lubricant because one hand has to act as a reel
break or using a hand-crank mechanism such as a film editor. Overlapping
sections of the tape with lubricant is not a problem. Once you have lubricated the
tape end-to-end, Attach a section of leader to the opposite end of the tape. At this
point, you are done and can play the tape. Presuming that you started with side
1, you can simply flip the tape onto the supply reel and start the transfer. Know
that you will be starting with side 2. This saves rewinding the tape if it’s been
recorded in both directions.
Caveat; Although I have used the previously described process many, many
times, the process I now use for lubricating audio tapes involves a custom built,
stationary felt pad. (Fig. 3) I evolved to the stationary felt pad method because it
was somewhat faster (I have transfered a lot of tapes) and it is more of a hands-
free operation. If the tape is in poor condition and/or the backside needs to be
cleaned, I will use the method described above.
Fig. 3
There is a considerable amount of useful information at the Last Factory website.
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© Corey Bailey Audio Engineering