Thanks for doing this important analysis. Hopefully this may suggest a
solvent that can effectively take on the long-lost role of Freon TF, and
Trichlor?
Steve Greene
Audiovisual Archivist
Office of Presidential Libraries
National Archives and Records Administration
(301) 837-1772
On Tue, Oct 21, 2014 at 2:31 PM, Karl Fitzke <[log in to unmask]>
wrote:
> Hello again to everyone who has had some interest in this case. Thanks
> again for that interest.
>
> After having met with Cornell Plant Science Dept Mycologist, Kathie Hodge,
> who determined that our material was not mold, I got some encouragement
> from Eric Breitung at the LOC (thanks, Eric) which bolstered my own hopes
> of contacting the Cornell Chemistry Dept. We both believed there were good
> odds they could characterize our mystery material with a mass
> spectrometer. I was finally able to meet Michael Lenetsky there, and he in
> turn introduced me to Ivan Keresztes, who generously gave us some time and
> expertise with his mass spec (of which there are only a few hundred of in
> use in the US if I heard him right). Thanks very much to all of you in that
> chain of history. I hope I can return all the favors above somehow someday.
>
> Ivan determined that what we see on our tapes here is quite certainly
> Stearic Acid. My understanding is that this fatty acid is sometimes used
> as an audio tape lubricant dispersant. So it appears some of it simply
> exuded to the tape edges and surface (extreme environmental conditions?
> and/or poor formulation?). I mostly see it on the edges, but it does show
> up on the tape surface occasionally and sometimes exhibits a kind of
> crystalline growth pattern there. I'm just looking with the naked eye and
> a magnifying lens today, but I'll bring in a microscope to look more
> carefully tomorrow - maybe post more pictures where I've posted others (see
> below).
>
> Does anyone have alternative ideas about where this stuff came from and/or
> how it is used in tape manufacturing? Ivan wondered about the slip sheets
> maybe contributing, because they have this material on them too, and water
> wets to the sheet easier where the stearic acid is (perhaps because
> exudation took place at those spots?). I found that out when Ivan
> suggested I look for water solubility before coming over to see him.
> Didn't seem to work very well, and the mass spec results pretty much
> confirm that observation. The slip sheets also have a waxy feel to them,
> and Stearic Acid can be waxy.
>
> Stearic acid coming from Tape, Sheets, both?
>
> Now we figure out how to clean the tapes up anyway, and repackage in new
> shells.
>
> And by the way, we humans reportedly have Stearic Acid exuding from us all
> over. Ivan and I were very careful to not touch the tape and slip sheets
> with our bare fingers. He also did careful background measurements where
> we didn't see the white material and THEN looked for something new sticking
> out like a sore thumb as it did. I've posted a few pictures with the
> others posted earlier here: https://cornell.box.com/s/
> rafx7ue412ylu7svl0j6
>
> -Karl
>
> http://www.chemguide.co.uk/analysis/masspec/howitworks.html
>
> http://pubchem.ncbi.nlm.nih.gov//compound/stearic%20acid?
> r=chemical#section=Top
>
> http://www.google.com/patents/US3993824 ("find" stearic)
>
> http://lxsrv7.oru.edu/~alang/onsc/solubility/allsolvents.
> php?solute=stearic%20acid
> (stearic acid solubility in various solvents, clean up clues)
>
> --
>
> Karl Fitzke
> Audio Engineer
> Macaulay Library
> Cornell Lab of Ornithology
> 159 Sapsucker Woods Road
> Ithaca, NY 14850
>
> 607-254-1100
>
> [log in to unmask]
>
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