Re: [ARSCLIST] powder-like substance from open reel tapes

["Peter@xxxxxxxxxxxxx" <lists@xxxxxxxxxxxxx>]

John:

If you wipe the tapes, two tissues that are non-destructive are pellon
(available on rolls if you want to set up a semi-automated or automated
system) or Kimwipes EX-L from Kimberly-Clark (if you do the work by hand).

Burnishing is usually done by running the tape past a specially constructed
post on a winding mechanism.  Burnishing, when combined with a tissue wipe,
greatly increases the effectiveness of the cleaning process but there are
some specific cautions: Never run a tape over a burnishing post if the tape
exhibits 1) visible edge damage, 2) a brittle acetate base, 3)loops or
cinches in the tape pack or 4)has splices of unconfirmed integrity.
Burnishing tapes with these sorts of problems can cause serious damage.

Burnishing got a very bad reputation back in the 70's when a company was
selling cleaning machines that used razor blades.  Further research by NASA,
3M and Grumman came up with much safer and more effective burnishing
mechanisms that first used tungsten-carbide and ,later, sapphire.  The posts
have to be ground and polished to fairly precise specifications, need to be
positioned to intersect the tape within a limited range of angles and must
be maintained without any scratches or chipping to be safe.  If you are not
very familiar with burnishing tapes, it is usually best to limit yourself to
the less-effective tissue wipe only.

Peter Brothers
President
SPECS BROS., LLC
(201) 440-6589
www.specsbros.com

Restoration and Disaster Recovery Service Since 1983

> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:ARSCLIST@xxxxxxx]On Behalf Of John Loy
> Sent: Wednesday, September 29, 2004 9:56 AM
> To: ARSCLIST@xxxxxxxxxxxx
> Subject: Re: [ARSCLIST] powder-like substance from open reel tapes
>
>
> Thank you all,
> For you timely and in-depth responses. Peter your suggestion I believe
> is the closest to what I have encountered. The tapes I have show no
> physical or audible signs of sticky-shed syndrome. The tapes have also
> been cleaned of mold and stored properly in a humid and temperature
> controlled environment for some time. Most of these tapes are form the
> early 70's and in my experience that is just a little before sticky
> shed problems started occuring.The main indication that it may be a
> polyester chemical reminant is that the powder doesn't get on the tape
> heads so much as the areas of the tape path that the back of the tape
> comes in contact with. I will start wiping or burnishing the offending
> tapes before playback to see if it helps and of course I will keep you
> all updated. Once again thanks for your help and any other suggestions
> are welcome.
> John A. Loy
> Audio Preservation Engineer
> Southern Folklife Collection
> University of North Carolina at Chapel Hill
>
>
>
>
>
>
>
> Quoting "Peter@xxxxxxxxxxxxx" <lists@xxxxxxxxxxxxx>:
>
> > John:
> >
> > "Powder" on the surface of magnetic tapes has been identified in
> > laboratory
> > testing as: polyester from the base film (alternately identified as
> > tri-mers), sodium or calcium residue from the magnetic pigment,
> > surfactant
> > residue from the manufacturing process, various fatty acids from the
> > lubricant and flowering heads from mold.
> >
> > In most instances you can tell whether it is chemical residue or mold
> > by the
> > visible pattern on the tape surface PRIOR to running the tape.  Mold
> > has a
> > tendency to appear as round(ish) patches or thin threads.  The
> > chemical
> > residues have a tendency to collect in lines on the edges of popped
> > strands
> > following a strand or group of strands around part of the curve of
> > the tape
> > pack.
> >
> > Mold will contaminate your machinery and can be a serious health
> > hazard.
> > Non of the other chemical residues has been identified as being toxic
> > but I
> > have known operators to get headaches when they became too
> > inquisitive and
> > ended up with a face full of the powder.
> >
> > Neither chemical decontamination nor baking work well at removing the
> > powder
> > residues prior to playback and baking can actually increase the
> > amount of
> > powder on the tape surface.   Tissue wiping or burnishing will
> > usually
> > remove sufficient powder to allow uncompromised playback but the
> > powder will
> > often re-appear after a few days or weeks.
> >
> > If your tapes have been very cold, you can sometimes get long
> > crystals of
> > lubricant on the tape surface.  These crystals can be re-absorbed
> > into the
> > tape by gentle heating but this is a very different phenomena than
> > the
> > "powder" residues.
> >
> > Peter Brothers
> > President
> > SPECS BROS., LLC
> > (201) 440-6589
> > www.specsbros.com
> >
> > Restoration and Disaster Recovery Service Since 1983
> >
> > > -----Original Message-----
> > > From: Association for Recorded Sound Discussion List
> > > [mailto:ARSCLIST@xxxxxxx]On Behalf Of John Loy
> > > Sent: Tuesday, September 28, 2004 3:40 PM
> > > To: ARSCLIST@xxxxxxxxxxxx
> > > Subject: [ARSCLIST] powder-like substance from open reel tapes
> > >
> > >
> > > I was wondering if anyone had experienced a powderlike substance
> > from
> > > open reel tapes from the early to mid 1970's. The brand of tapes
> > are
> > > TDK. The powder has been gumming up the machine's transport yet has
> > not
> > > impeded play or audio quality. When I go to rewind a tape however,
> > it
> > > slows the machine and prevents a full rewind at which time I have
> > to
> > > clean the machine. The powder is a yellowish-brown and while it is
> > on
> > > the guides and heads of the machine looks organized but scrapes
> > off
> > > into a power. If you have heard of or experienced this problem
> > please
> > > respond and let me know what I can do about it or what effect it
> > may
> > > have on my machines or the tapes in a long term storage situation.
> > > Please ONLY helpful, polite inquiries.
> > >
> > >
> > >
> > >   thanks,
> > > John A. Loy
> > > Audio Preservation Engineer
> > > Southern Folklife Collection
> > > UNC Chapel Hill
> > >
> >
>