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RE: arsclist Pellon and thoughts on baking/Philosophy
See what happens when you don't check your email for a couple of days????
I did have a conversation with Richard at NAB - and for those of you who
haven't been to NAB - let me summarize that having a conversation at NAB is
sort of like having a conversation at a baseball stadium when the home team
is down 4 to 3 in the bottom of the 9th inning and you hear a bat crack and
everyone stands up - oh yeah.... what did you say???
Richard got some of it right and some of it ..... less then right. Let me
summarize briefly and comment.
First of all - there indeed has been a "study" done by a soon to be client
of ours who did a "blind" test and several expert listeners did determine
that tapes that had been baked DID sound inferior. This test was NOT done by
VidiPax. WE were one of the vendors that was tested - the expert listeners
did not know which tapes were treated by what technique. It was a very
complete test and the first of its kind that I know of. I doubt that it will
be published because it was done specifically for them to choose a vendor.
Happily (for us) we were chosen. The client has NOT publicized this yet, but
when they do - I will send a copy of the press release to the list. I said
NOTHING about percentages - 60% or otherwise. I don't know the percentages -
and as I said this was a study of the sound of samples of tapes before and
after treatment for sticktion as well as before and after digitization. I
really can't go into it in any more depth.
VidiPax - as a "policy" does not use ANY ONE WAY TO TREAT ALL TAPES. This is
a philosophy that goes back to when I found the company. In fact on our web
site there is an article that I wrote a LONG time ago entitled: Confessions
of a Videotape Restorer or How come These Tapes All Need to be Cleaned
What I wrote in that article I believe is still largely true today. That
essential truth is that there are so many different issues with tapes that
no single technique can (or could ever) fix ALL of the problems that could
occur. An extension of that logic is that no one treatment is capable of not
causing other problems if applied incorrectly for an inappropriate malady.
Clearly a splint is an inappropriate remedy for a headache, and the same can
be said of an analgesic for a multiple fracture (although easing the pain is
not a bad plan too). So we use different techniques for different problems.
You also need to understand a bit about the nature of the work we do at
VidiPax. We do ALLOT of work both audio and video - so what may be
appropriate for our situation and production environment may be
inappropriate for someone else. We now have almost 40 people doing this work
at our company, and an investment of over 4 million dollars of equipment, so
the approaches we can now take are possible because of a certain "economy of
scale" that could never be financially viable for a smaller operation (we
know because we WERE a smaller one) - so our needs and approaches differ
also because of the nature of what we do and how we do it.
That all said - I am more convinced now then ever that for HELICAL
recordings - baking is NOT a good plan - unless there is absolutely NO other
alternative and all of the other alternatives have been exhausted. As Sarah
Stauderman stated - "do no harm" is an important credo in this line of
work - and we were pleased to have done the joint study with the Smithsonian
to find out in fact if the technique we used would in fact change the
chemical nature of the media - and we were pleased that it did not. When
using baking on helical recordings we have had problems playing tapes back
after being baked. Meaning that we had sections that we COULD play back (and
sections we could not) and after going back and baking we could NOT recover
the sections that we formerly could play back. I have my own "guess" what
happened - but I did not have the time to investigate further.
If you consider what happens to base film during manufacture - you realize
that the basefilm that is then coated and slit from the jumbos is not
necessarily dimensionally "perpendicular" to the way that the film was
manufactured and put on the jumbo in the first place. Further, there is no
reason to assume that the base film will necessarily be dimensionally stable
in all directions or linearly throughout the pack even when the stresses are
different. There are other issues such as even if a flange touches a section
of the pack - and all of these can cause different dimensional movement not
only in the LENGTH of the tape (longitudinally) but also there can be
changes in width and even changes through out the "plane" that the tape is
in (you need to think in 3d space to envision this... much easier to show
it). Now in 1/4" longitudinal analog recordings the tolerances in this type
of space is so broad that one would not even notice - but consider what
would happen to a helical recording if you had changes of this sort during
the length of a track - a track that cuts ACROSS the tape. Further -
imagine it with azimuth recording. Video is MUCH more critical in this
regard - and changes of this sort can indeed make a tape difficult or
impossible to track properly.
piece of tape
now dimensionally shift it - you would LIKE it to shift
but what if it was non linear like
Then you got a big problem for helical scans
So we have had problems with baking - and as a result we RARELY use it. We
have a fancy schmancy convection lab oven. Right now it is in a storage area
unplugged and has been so for quite some time. Yes we have it but we just
don't use it much - we have found better ways - and Pelon is ONE of the
Finally Richard was concerned about the oxide that is removed in the
process. Could TOO much oxide removal cause a problem? Yes - but it would
have to be ALLOT. Let's get back to basics. We are dealing with RF output
here - and one needs to consider the RF output over unit area as it relates
to the RF presented at any given unit time. A loss of oxide can be thought
of as an RF void in the most drastic case - but consider how MUCH oxide
would have to be removed for a void - and then think of how little a process
such as the one we use removes over the entire length of the tape. We do
remove a MINUTE amount of material - and one could make a VERY good argument
that a good percentage of that material if it were not removed would likely
adhere to fixed guides (if there are any - we have only moving guides in our
specially modified Studer A820 machines that we use for playback - for audio
obviously) or the heads themselves. The removal of that material actually
allows better tape to head contact and provides better and more consistent
tape to head contact. And that has been our experience with both fixed and
rotating heads. Considering the relatively high RF energy output of tape
(even pretty old tape) and this is just not an issue - other then perhaps in
S/N and again - improving tape to head contact by keeping the gap clear of
debris keeps output high - and therefore better S/N. And that is how it
works in the real world as we have seen it in our lab.
Almost finally - considering that burnishing a tape first by playing once
before initial recording (as several people have reported including
manufacturers recommendations) actually INCREASES RF output confirms the
logic of this approach. Burnishing and loose particulate removal is actually
used in tape manufacture - so we are not really reinventing anything here
And very finally..... Richard and I did discuss what I consider the
extremely important need for a LAB to actually be working and testing
different technique as well as different issues with tape manufacture and
formulation and longevity issues. We agreed on an urgent need in this area.
At VidiPax we do a bit - but we are a small company in the scope of things -
and we could never fund this type of work. The tape manufacturers clearly
have no interest in it. So it has not happened. It would be great if some
day it could.
General Manager VidiPax Division
VidiPax - The Magnetic Media Restoration Company
450 West 31 Street
New York, N.Y. 10001
212-563-1999 ext. 102
Moderator: AV Media Matters Listserve
To subscribe to AV Media Matters Listserve send an email to:
> -----Original Message-----
> From: owner-ARSCLIST@xxxxxxxxxxxxxxxxx
> [mailto:owner-ARSCLIST@xxxxxxxxxxxxxxxxx]On Behalf Of Richard L. Hess
> Sent: Friday, May 11, 2001 5:30 PM
> To: Sarah Stauderman
> Cc: ARSCLIST@xxxxxxxxxxxxxxxx; harry_rice@xxxxxxxxx
> Subject: Re: arsclist Pellon and thoughts on baking/Philosophy
> I wonder if the baking process is any worse than the tape sitting in an
> aluminum shipping container on the tarmac at LAX in the summer waiting to
> be loaded on the Fed Ex plane--we all are guilty of shipping our master
> tapes by Fed Ex and worse without temperature controls.
> I have heard one horror story of baking--but only one.
> While I am all in favor of doing no harm to original artifacts we
> also get
> to the question of whether the artifact or the content is the important
> item. Most of the people I'm working with -- and granted they're not the
> Smithsonian -- want the content and could care less about the
> carrier. They
> want the content to sound absolutely as good as it can. Several
> people have
> come to me after horrid transfers and have said can you do anything? I
> agree with Mr. Lindner: go to an expert first not after you've made the
> problem worse.
> I have seen sticky-shed so bad that a reel would not self-unroll. Many of
> the tapes with sticky-shed will leave stuff on the guides, but
> will unroll
> easily. Some will pull so hard you fear the oxide will be left
> behind...almost like Scotch 111 removable mending tape being
> pulled off the
> What weight Pellon do you suggest? I'd like to try it, but I won't on a
> tape I have to restore--if what I see on tape guides is any indication
> there will be a lot more on the Pellon if it's going to remove all the
> debris that is likely to cause stickiness.
> Besides, the Pellon treatment isn't tested in any scientific way, either.
> It's another process that has been evaluated by empirical test and while
> Ms. Stauderman and Mr. Lindner (both of whom I have great respect for)
> worry about the baking process, I'll stand out here as one voice worrying
> about removing enough material to make the tape non-shedding by a wiping
> process. I know in previous emails Mr. Lindner has said the amount of
> material removed is infinitesimal, from what I've seen on SOME tapes and
> what comes off on the polished guides when I have to wind the tape before
> baking (which I hate to do) I would be amazed that there wouldn't
> be a huge
> amount of oxide on the Pellon.
> What I do know is that prior to baking, the tape's oxide surface seems to
> be soft and tacky. After baking it is hard and shiny just like new tape.
> Once long ago I did well in the Chemistry Achievement Tests but never
> pursued it further so you can take this with a grain of salt, but what I
> think I'm seeing in the sticky-shed tapes appears almost to be a state
> change from solid to goo (conceptually, think of ice to slush). From my
> observations it doesn't appear to happen to the surface only, but
> rather it
> appears to be deep within the binder/oxide paste that is placed
> on the base
> I don't have any bad sticky-shed tapes at the moment, but I will look for
> one--or maybe try to make one. Do you think if I leave a reel of 1981
> vintage 456 in my bathroom for a month of showers it will be hydrolized
> enough? I live in LA--I have to do something dramatic to match
> the climate
> of the Pacific Northwest where my worst sticky-shed examples came
> from (and
> have been returned).
> I think we perhaps come from two different worlds. Hopefully, at the
> Smithsonian (and most of VidiPax's other clients) material is
> stored in at
> least office environments and often special-purpose archival storage
> facilities. Contrast this to 456 kept in a wooden barn on a small island
> off the coast of Vancouver Island. Trees hanging over the barn.
> No central
> heating only space heaters in some rooms. I've heard of other tapes kept
> against a stone basement wall in lake country. This is the fate of many
> masters for LPs that were made in the 70's and 80's (if they didn't find
> their way into the dumpster). The ones from the small island had
> collectively sold probably 120,000 copies--not huge but respectable. We
> want to do a retrospective CD set.
> Anyway, I spoke at length with Mr. Lindner at the NAB and we're
> in violent
> agreement that studies should be done to see what the problems
> are. I don't
> have a citation, but the 1dB loss at high frequencies due to baking was
> from an Australian study as I understand it.
> I'm not even sure how you do the test to attribute the losses to the
> baking. Couldn't the losses be attributable to the hydrolization? For
> example if a hydrolized tape that has been baked loses 1dB at 20kHz
> compared to a non-hydrolized tape that wasn't baked how would you know if
> it was the baking or the hydrolization. We would know if baking a
> non-hydrolized tape yields the same loss, but it's not conclusive
> <soapbox mode on>
> The following is not really addressed to anyone in particular but
> to all of
> us in general.
> Now let's move on to acidosis or vinegar syndrome (VS) to make a
> point. The
> Kodak Molecular Sieve material is reported to retard
> deterioration from VS.
> Some 1940's vintage BASF/Agfa/IG Farben Magnetophonband and
> Scotch 111 that
> I recently transferred suffered from a vinegar smell but still
> played well.
> But for how much longer? How does VS affect tape? What is the timetable
> compared to film? What can slow it? At SOME POINT we will need
> to make the
> decision to copy the material and abandon the current carrier.
> We've had to
> do that with nitrate based film stock. At some point we'll have to make
> that decision with audiotapes. It seems that we may have abandoned
> newsprint too soon in favor of microfilm and I know that archivists and
> librarians are smarting from that one and are being called to
> task for that
> decision, but let's make sure we don't lose assets by inaction. Let's get
> material transferred to a reasonable format before it's too late.
> may solve some of the problems for us.
> We have funding, staffing, and technological challenges to
> overcome but we
> have to make a concerted effort to decide how to save this
> material before
> it's too late. When will it be too late? I can't say. Tomorrow won't
> be...20 years might be for some material.
> One estimate is that there is 50M hours of material in the world to
> transfer (yup- fifty million). Some think that's conservative.
> Assuming 4:1
> time for transferring (and let's not even say "to what") that's
> 200 million
> person hours or 100 thousand person years of transferring.
> <soapbox mode off>
> At 04:13 PM 05/11/2001 -0400, Sarah Stauderman wrote:
> >To clarify about Pellon: it is non-woven polyester (fabric), also known
> >as polyester web.
> >One issue that it seems to me is always avoided in discussions about
> >baking is that it has never been tested in a scientific
> laboratory set up
> >to compare and analyze the effects of baking. There's lots of anecdotal
> >evidence that says that baking is ok and that it works (there's a patent
> >on it, in fact).
> >But, speaking as a conservator, it is simply wrong to use untested
> >treatments on cultural artifacts. At the very least, audio
> engineers who
> >use baking need to understand what the long-term effects of
> baking may be,
> >or explain thoroughly to clients/cultural institutions that baking may
> >result in irrevocable damage to the original artifact. Perhaps
> baking is
> >the only method to use on tapes with heavy sticky-shed resulting from
> >hydrolysis. If this is the case, we still need documented
> evidence of its
> >efficacy and implications.
> >Meanwhile, I participated in a study of cleaning videotapes
> (3/4" u-matic
> >was the format, and the brand was Ampex, and BASF) using non-woven
> >polyester. This report was given at the American Institute for
> >Conservation annual meeting in June 1999. The scientist, Mary Baker,
> >examined the surfaces of tapes using FTIR. There was no chemical change
> >before and after cleaning. Unfortunately, the tape sample was too small
> >and the means to study a change in picture quality was not
> available. We
> >also did not get the enormous amount of residue on the cleaning webbing
> >that Mr. Hess has observed. In the end, we felt that no chemical change
> >was a good indicator of the utility of cleaning with polyester webbing,
> >but that it warranted additional study.
> >Incidentally, this study was carried out at the Smithsonian Center for
> >Materials Research and Education, which is slated to be eliminated from
> >the Smithsonian in December 2001. The cleaning, I should also mention,
> >was carried out at VidiPax's New York lab. I wish that there was a
> >concerted effort to characterize treatment activities and their
> >implications by audio restorers and video restorers. Groups
> like ARSC and
> >AMIA need to work with SMPTE and standards organizations to do this
> >research. If I had a lab, I would.
> >Opposed to baking until it's proven otherwise, or as a very last
> resort, I
> >remain, wishing you all best luck with your materials,
> >Sarah Stauderman
> >Sarah Stauderman
> >Preservation Manager
> >Smithsonian Institution Archives
> >202-357-1421 x 56
> > >>> lists@xxxxxxxxxxxxxxx 05/11/01 12:20PM >>>
> >pellon (a thin stiff white fabric found in craft and fabric stores) (as
> >found on the Web)...
> >To be totally fair, Jim Lindner is a much more experienced
> person than I in
> >dealing with tape problems, although I'll confess to being
> resourceful and
> >obtaining good results. We philosophically disagree on the superiority of
> >the two processes:
> >Lindner is horrified at the thought of baking. He tries to avoid
> it at all
> >I, on the other hand, am greatly concerned about wiping tapes
> until all the
> >goo is off because I see the stuff on the wipes as containing oxide in
> >now-scrambled orientations that used to contain the signal I'm trying to
> >get off the tape.
> >In one double-blind test, Lindner found that about 60% of the listeners
> >(not much above the 50% random chance) (if I correctly recall his telling
> >me on the noisy floor of the recent NAB show) found some deficiencies in
> >the low frequencies of baked tapes as compared with wiped tapes. Now, I
> >don't know how you can do double-blind tests of this with precisely the
> >same material without copying and the copying process itself
> (especially at
> >15 and even more so at 30 ips) introduces substantial low frequency
> >anomalies due to "head bump" phenomena. So I am not sure if Lindner's
> >reported double blind test is hearing the restoration process or some
> >anomaly in the copying process.
> >As to baking, there have been some reports of a 1dB loss of the highest
> >frequencies. I have baked one set of tapes twice and on the second baking
> >reproduced them on a superior machine as opposed to the one
> after the first
> >baking. The tapes sounded better after the second baking on the superior
> >machine, so the machine difference is more than the difference in
> >baking--an IMPORTANT point to remember.
> >My comparison of machines was between a ReVox A77 and a Sony APR5003V. In
> >my mind, the APR is one of the five best machines ever made, the others
> >being the Studer A820, the Ampex ATR-100, the Ampex MR-70 (if you want
> >tube), and the Nagra T. The ReVox A77 was a competent low-end
> machine that
> >worked as well as many other machines in its price range. If you've got
> >high-end tapes, they deserved to be digitized from a high-end machine.
> >More than you asked...but it's all related!
> >At 10:54 AM 05/11/2001 -0400, harry_rice@xxxxxxxxx wrote:
> > >Richard:
> > >
> > >What are Pellon wipes?
> > >
> > >Harry Rice
> > >Berea College
> > ______
> > >Subject: Fwd: BOUNCE arsclist@xxxxxxxxxxxxxxxxx: Non-member sub
> > >From: <ARSCLIST@xxxxxxxxxxxxxxxx> at berlink
> > >Date: 5/11/2001 9:20 AM
> > >
> > >
> > > >Date: Thu, 10 May 2001 12:36:56 -0700
> > > >To: Language Laboratories and Archives <language-labs@xxxxxxxxxxxx>
> > > >From: "Richard L. Hess" <richard@xxxxxxxxxxxxxxx>
> > > >Subject: Re: arsclist sticky shed
> > > >Cc: ARSCLIST@xxxxxxxxxxxxxxxx
> > > >
> > > >Hi, Barbara,
> > > >
> > > >There are resources on my Web page at
> > > >I think at least some of these people deal with sticky shed syndrome.
> > > >VidiPax does it by wiping with Pellon wipes, most of the
> rest of us bake.
> > > >I've had good results with a whole heap'o'tapes but it's
> never guaranteed
> > > >and while we all take the utmost care we cannot be held
> liable for loss of
> > > >the master--I think that's pretty standard.
> > > >
> > > >If it's only one reel I could look at it for you. If it's
> much more than
> > > >that, I don't have the time. $100 hour is close to the going
> rate (I think
> > > >VidiPax charges $95). That's per hour of studio time not per
> running hour
> > > >of program. My general estimate is that it takes from 4-10x
> depending on
> > > >what needs to be done and how good you want it. The 6x is typically
> > > >finessing individual dropouts--you've got to find them which means
> > > >listening and watching.
> > > >
> > > >What is the tape format, what is the tape brand, how long is it?
> > What's on
> > > >it? what do you want to do with the content?
> > > >
> > > >I see you're from the language labs. If it's just word and it's a
> > > >continuous tape (no splices) it might not even take 4x. If
> it is music
> > with
> > > >lots of splices for CD re-release, It generally approaches
> the 10x figure.
> > > >
> > > >I've done reel tapes as early as 1947 with some Bing Crosby
> excerpts on
> > > >them (no sticky shed, but lots of problems) but most of my
> current work is
> > > >centered on folk music from the 70's and 80's when
> sticky-shed was at its
> > > >worst.
> > > >
> > > >Good luck finding someone to do it!
> > > >
> > > >Cheers,
> > > >
> > > >Richardy copying process itself (especially
> > > >
> > > >
> > > >At 01:12 PM 05/10/2001 -0500, Language Laboratories and
> Archives wrote:
> > > > >Hi, We just had a case of sticky shed, and the company we
> dealt with
> > many
> > > > >years ago is no longer in business. Who are you all working with?
> > > > >
> > > > >Barbara Need
> > > > >UChicago--Language Labs
> > > > >-
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> > > > >from the author of the post.
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> > >-
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> > >from the author of the post.
> > >
> > >
> > >
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> >from the author of the post.
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