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

[John Loy <jloy@xxxxxxxxxxxxx>]

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
> >
>