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
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