Hi, Tom and Jim,
This is an interesting discussion as I have had a very minor success
rate baking an Ampex 467 DAT. I am compiling field reports of
linear-track 467 reel tape becoming problematic. I think we saw some of
this about seven years ago with some Mitsubishi X80 tapes that appeared
to have "bit splitter" issues, but I have suggested it might be
stick-slip collapsing the eye pattern.
My experience (other than 100% success rate with one DAT tape--not
anything to base anything on) is strictly with longitudinal tapes. I
think that Martin has a mixture of issues and from very limited
experience, the stuff which bonded did so because it was pulled out
during the un-baked rewind.
I have baked about 8-10 reels of 1" 9600' assorted instrumentation tape
on 14" hubs (the flanges do NOT fit in the larger American Harvest, but
the pancakes do). They were fine.
This is nasty and will only get nastier. I wish we had someone with deep
pockets funding analytical labs populated by people who understood tape!
I do appreciate both of your comments and this is a healthy debate!
On 2012-02-08 7:22 PM, Tom Fine wrote:
> Hi Jim:
> I should have stated that my comments were limited to audio tape (1.5
> mil and 1 mil thickness). I've never messed with the thinner tapes and
> I don't know what the consequences of any of this are with
> non-linear-recorded tapes or information-dense formats.
> With what Martin is describing, I can't see why baking does what he is
> describing it doing. Do you or anyone else have some facts as to the
> mechanism that would cause the globs to remain sticky "tar-balls"? All
> I can think is, they are globs of concentrated goo that can't be baked
> back to non-gooey-ness at a temperature and time that won't damage the
> playable tape. If it were me with those tapes, I would invest a lot of
> time into seeking backups, even off-air recordings if they are radio
> or TV soundtracks. I think you stand a better chance of getting usable
> audio that way.
> Martin, have you tried freon on those gobs? That's nasty stuff but it
> worked really well on splices that had gone gooey on 1950's
> brown-oxide tapes that were otherwise fine. The method was, use freon
> to dissolve the splice-goo on the outside of the tape pack, slowly
> wind to the splice, then very conservatively dab freon on whatever
> small globs of splice-goo were on the tape. If the mylar back of the
> splice had dried out and thus broke the splice, very conservative
> application of freon was used to dissolve all the white dried out glue
> and sticky goo. Then a new splice was applied (cleaning and
> re-splicing taking place in a splicing block). This worked on 1/4",
> 1/2" tapes (both 1.5 mil thick) and 35mm mag-film. I'm wondering if
> you can rig up something similar to attack those globs. I think your
> problem might be that by the time you expose a glob, it's damaged the
> playback surface (oxide)?
> -- Tom Fine
> ----- Original Message ----- From: "Jim Lindner" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Wednesday, February 08, 2012 6:19 PM
> Subject: Re: [ARSCLIST] Tape Backcoating
> Tom there are many instances where baking before cleaning is not
> advised, and Martin nicely described just one of them. I would extend
> that and say that there are many situations where baking is not
> advised at all, and if so only after other processes have been tried
> beforehand and have failed and all other avenues exhausted.
> On this list, posters are used to discussion of primarily 1/4" audio
> tape. There are, however, many different types of tape including ones
> that have completely different binder system from 1/4" audio. Some
> stocks have base films that are just fractions of the thickness of
> 1/4" audio and have recording densities orders of magnitude higher
> then audio tape. Magnetic Media is used in many different application
> areas and have totally different formulations, thicknesses, and
> characteristics such as abrasivity (for example) are totally
> different. Different tapes are designed for differing head to tape
> contact and head tip penetration, and all of these factors are
> critical in the development of appropriate product for the recording
> format, and they are far from the same. Consider the differences
> between MP and EM tape for example - there is almost nothing the same
> about them other then them being called tape and them having
> recordings on them. In almost all situations baking EM tape would be
> ill advised.
> Some even have the word Video or Data or Instrumentation before the
> word Tape. These tapes have different formulations and respond
> differently to baking, and even more to the point, SSS is not just one
> thing and has become a general description to a wide variety of
> maladies that vary a great deal in terms of the amount of tenacity of
> the adhesive as well as the location of it and the thickness and
> composition of it. While a tape may be "sticky", the problem may not
> be SSS and so the appropriate treatment of it may vary considerably.
> Not all tapes have linear tracks - and tapes that have helical
> recordings have some rather different issues then those with linear
> tracks. Deformation in base film of linear recorded tracks -
> particularly if they are wide half or full track audio recordings
> likely would not be an issue. Deformations of basefilm for videotape
> that have helical recordings and therefore have tracks across the
> tapes (and in particular azimuth recordings on high density recording
> media), can lead to mistracking issues and reduced rf output. This can
> lead to the loss of servo lock and catastrophic failure to play back.
> This is because non-linear basefilm deformation can cause the tracks
> to skew. Playing back skewed tracks in some formats is extremely
> difficult - particularly when the skew is not consistent from one
> section of the tape to the next - and the result can be extremely
> serious. Some machines can compensate and other not, and this varies
> for format type as well as particular machine models and even to the
> specific machine being used for playback and its specific calibration
> at that time. Interchange becomes a huge issue because the deformation
> of the tracks creates a non-standard recording = sometimes - and it
> may only last a millisecond or two.
> Certain tapes have been exposed to damage during their life that would
> be compounded by baking. Tapes that have, for example, particulate
> contamination or have other types of contamination caused by floods or
> exposure to caustic environments should not just be stuck in the oven
> because they are sticky. I have personally dealt with tapes that have
> become septically contaminated - and are sticky, but there clearly may
> be other mechanisms in play that can cause the stickiness. Physically
> cleaning tape prophylactically when performed correctly can and has
> often pre-empted the need for baking in virtually thousands of tapes
> that I personally was involved with over a decade. However, there is a
> certain amount of skill and expertise required.
> Taking 2 Asprin and calling the Dr. in the morning may be fine for the
> common cold but not likely helpful for Appendicitis or Cancer.
> Jim Lindner
> Email: [log in to unmask]
> Media Matters LLC.
> 450 West 31st Street 4th Floor
> New York, N.Y. 10001
> eFax (646) 349-4475
> Mobile: (917) 945-2662
> Media Matters LLC. is a technical consultancy specializing in archival
> audio and video material. We provide advice and analysis, to media
> archives that apply the beneficial advances in technology to
> collection management.
> On Feb 8, 2012, at 4:48 PM, Tom Fine wrote:
>> Who would "advocate" fast-winding or playing a sticky tape before it
>> is baked? That is idiotic advice and should be ignored! The tape is
>> _STUCK_ (ie "sticky") and it will _SHED_ (ie layers of the tape will
>> separate) if the tape pack is molested until it has been baked and
>> cooled. I've never, never had a problem with tapes de-layering after
>> they've been baked the proper time at the proper temperature. I have
>> had tapes (Scotch 227, 3600' reels) that still deposit moderate
>> amounts of white goo on the guides after proper baking and cooling,
>> but they played back fine (there wasn't enough goo to jam up the tape
>> I can't understand why there is still any "debate" about this -- a
>> sticky-shed tape needs to be baked before anything is done to the
>> tape pack (playback, fast-winding, etc). The good news is, plastic
>> reels can withstand recommended baking temps and times, and if they
>> end up a little warped, just gently/slowly spool the baked tape onto
>> a new reel and dump the warped one. If the tape is on a hub, I
>> recommend you place a flange under the hub, bake it and then handle
>> it very carefully because baking tends to result in a loose tape pack.
>> -- Tom Fine
>> ----- Original Message ----- From: "Nigel Champion"
>> <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Wednesday, February 08, 2012 3:32 PM
>> Subject: Re: [ARSCLIST] Tape Backcoating
>> Perhaps the problem here is not that the tape was baked but that it
>> was re-wound before baking! I cringe when I see this advocated.
>> Pressure on inner windings in conjunction with sticky shed syndrome
>> can create a core as solid as a hockey puck, especially if storage
>> conditions have been sub-optimal. In such situations, pinning and
>> delaminating is almost inevitable.
>> Good luck
>> Nigel Champion
>> Archive Manager & Audio Conservator
>> Archive Of Māori & Pacific Music
>> The University of Auckland
>> Private Bag 92109
>> Auckland 1142
>> Tel: 64-9-373-7599 ext 85008
>> Fax: 64-9-373-7441
>> Web: http://www.library.auckland.ac.nz/ampm/
>> -----Original Message-----
>> From: Association for Recorded Sound Discussion List
>> [mailto:[log in to unmask]] On Behalf Of Jim Lindner
>> Sent: Wednesday, 8 February 2012 6:41 p.m.
>> To: [log in to unmask]
>> Subject: Re: [ARSCLIST] Tape Backcoating
>> The backcoat binder system chemistry is in most cases similar if not
>> identical to the oxide binder system, so it sounds like you really do
>> have a mess. Removing one without damaging the other will be
>> extremely difficult. It may be that using a pellon wipe to try to
>> remove it not chemically, but through successive wipes at high speed
>> MIGHT remove enough of it to allow playback, but I would have to see
>> it to tell. It also might be that a low concentration of a solvent
>> will remove the "low hanging fruit" first - so again a pellon wipe
>> with a dilution of solvent and water might work - although you then
>> have the rh issues to deal with, which might also cause problems.
>> These are the "fast and cheap" approaches that might work - but then
>> again you have tried fast and cheap already and have reaped the rewards.
>> In the past I have used modified film rewinds (with a NAB hub to
>> accommodate tape) and placed the supply reel on one side and the take
>> up reel on the other side - oxide side up in your situation. In
>> between you have your work surface, and you now hand "polish" the
>> tape using a solvent. Unofficially I might suggest experimenting with
>> the now banned 1:1:1 trichloroethane using this modified film rewind
>> approach. Although banned, it may still be available in small
>> quantities from chemistry supply facilities, and yes it is expensive.
>> Fortunately you do not need much. Read the MSDS very carefully,
>> handle very carefully, adequate ventilation, follow all guidelines,
>> hands end eye protection, ventilator - all of it. This will be a
>> slow hand process. As you get experience you will be able to remove
>> the goo and if you are careful in your application leave the stuff
>> under it. Too much solvent and too much pressure and you will wipe
>> all of it. You "polish" slowly foot by foot winding the completed and
>> clean tape on the take up side. Based on your description you will
>> need to also clean the back coat side because it sounds as if you
>> have softened it enough so that it will reapply itself to the oxide
>> if rewound on it directly based on the pack pressure.
>> Yeah, well you really do have a mess and a science project. This is
>> just one reason why I am not a big baking fan. There are not too many
>> cases where I see media that is dumpster bound. Next time you might
>> consider cleaning before baking.
>> Jim Lindner
>> Email: [log in to unmask]
>> Media Matters LLC.
>> 450 West 31st Street 4th Floor
>> New York, N.Y. 10001
>> eFax (646) 349-4475
>> Mobile: (917) 945-2662
>> Media Matters LLC. is a technical consultancy specializing in
>> archival audio and video material. We provide advice and analysis, to
>> media archives that apply the beneficial advances in technology to
>> collection management.
>> On Feb 7, 2012, at 5:18 PM, Martin Fisher wrote:
>>> Hey Guys,
>>> What chemicals are good to strip backcoating off reel tapes.
>>> NO! NO! NO! I don't want to send them out for stripping. Way too
>>> expensive. I don't even want to strip the entire tape.
>>> What I need is to clean the backcoat off the oxide layer. The tape
>>> was given a "B" wind after developing sticky shed and, in places,
>>> some backcoating "hairs" got stuck between adjacent layers and
>>> adhered to the binder. This was exacerbated further by baking. The
>>> stuff just turned to goo and spread out on the surface of the binder
>>> like butter on bread in the oven.
>>> Alcohol works but also dissolves the binder an many instances. No
>>> way of knowing the tape stock since the boxes are generic, reels are
>>> haphazard but the backcoating is of the thick, matte gooeyer variety.
>>> Any help appreciated! :-)
Richard L. Hess email: [log in to unmask]
Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX
Quality tape transfers -- even from hard-to-play tapes.