For whatever its worth, a blast from the past in the form of an email thread below (also including Steve Green). Related photos here: <https://cornell.box.com/s/rafx7ue412ylu7svl0j6> https://cornell.box.com/s/rafx7ue412ylu7svl0j6 Karl Fitzke Audio/Visual Specialist 214 Olin Library Ithaca, NY 14853 607-255-5521 [log in to unmask] ________________________________ From: Association for Recorded Sound Discussion List <[log in to unmask]> on behalf of Karl Fitzke <[log in to unmask]> Sent: Monday, May 11, 2015 5:09 PM To: [log in to unmask] Subject: Re: [ARSCLIST] Audio Cassette White Contaminant - Mass Spec Results! Stearic Acid, Cleaning All, I've returned to this project of long ago, and found that isopropyl alcohol works much better atremoving the stearic acid than a record cleaning product I have on hand did(Nitty Gritty Pure 2, chemical content unknown). The record cleaner was actually quite ineffectiveand alcohol was very effective. If/when we decide to clean these tapes(low priority content), I will certainly be takingEric's advice to keep an eye on what happens to the oxide. And I will make sure tape dries well before it hits the takeup reel on anything we gin up to clean the tapes with. There are legendshere of some studenthelpNOTdoing thata long long time ago, and effectively destroyingsome open reelsbefore someone elsenoticed and called an end to what they were doing. -Karl P.S. Is it my imagination, or do some of the tapes look better after just sitting around in my air-conditioned office(out of our ultra-controlled environment) for so many months?! On 10/23/14 1:38 PM, Karl Fitzke wrote: > Glad you clarified the "Disc Cleaner" option. Iwas wondering about > whether or not a rinse would be recommended, and should have asked > right away. Will proceed cautiously with that too if we try it, since > it may be where no one has gone before. Your expertise is greatly > appreciated. > > On 10/23/14 1:29 PM, Breitung, Eric wrote: >> >> I didn’t mention it, but with the non-ionic surfactant in water >> option, the advantage is that you won’t dissolve much else in the >> tape. You will, however, need to rinse or wipe with water after >> wiping with the cleaner to make sure you’re not leaving behind any >> residues. >> >> I’ve only done testing using it and other cleaners on lacquered >> discs, by the way, so this is by no means well researched on magnetic >> tape. >> >> *From:*Karl Fitzke [mailto:[log in to unmask]] >> *Sent:* Thursday, October 23, 2014 1:24 PM >> *To:* Breitung, Eric; Steve Greene >> *Cc:* [log in to unmask]; Ivan Keresztes >> *Subject:* Re: [ARSCLIST] Audio Cassette White Contaminant - Mass >> Spec Results! Stearic Acid >> >> Eric, >> >> We did actually see some palmitic acid as well. >> >> Thanks for your comments. I'll try a little isopropanol, in >> plentiful supply here already, experimenting as you suggest. I also >> have some Disc Doctor cleaner readily available (at home) that I'll >> also try. >> >> -Karl >> >> On 10/23/14 11:40 AM, Breitung, Eric wrote: >> >> I agree with Karl - Stearic acid can often be a hydrolysis product >> of lubricants such as castor oil. This is found on much older >> media like lacquered discs as a white exudate, but it is nearly >> always paired with palmitic acid when it comes from castor oil, so >> I’m not sure what lube they were using to get just stearic acid. >> >> Careful using some of the solvents on the list provided for two >> reasons: 1) toxicity – like trichloroethylene = likely carcinogen >> and 2) stripping more than just the stearic acid from the surface. >> If you only need to get one play out of the tape, stripping the >> surface with isopropanol may work and allow a play, but I’d >> definitely try it on a small area and let it dry to see if there’s >> loss of adhesion of the magnetic particles – or any other affect. >> If you want to be able to play it a second time in a few months or >> years, and you’ve stripped away more than just the surface >> exudate, you may make the tape ‘dryer’ and more likely to show dry >> shedding. Alternatively, you might try something like a >> water-based cleaner with non-ionic surfactants (like Disc Doctor >> record cleaner) first – with very gentle wiping and a soft cloth – >> like a lens cleaner. >> >> Thanks for keeping me in the loop >> >> Eric Breitung >> >> *From:*Karl Fitzke [mailto:[log in to unmask]] >> *Sent:* Thursday, October 23, 2014 10:57 AM >> *To:* Steve Greene >> *Cc:* [log in to unmask] >> <mailto:[log in to unmask]>; Breitung, Eric; Ivan Keresztes >> *Subject:* Re: [ARSCLIST] Audio Cassette White Contaminant - Mass >> Spec Results! Stearic Acid >> >> Glad to do it, Steve. But Ivan gets the real thanks. >> >> I also want to note to everyone that you Steve, quite awhile ago >> noted this may be a "remnant of the lubricant". Peter Brothers >> had also noted to me earlier, that one of the possibilities he >> thought about after seeing the photos was a "fatty acid or >> stearate from the lubricant". Tom Fine mentioned "breakdown". >> Seva at soundcurrent mentioned leaching onto surface (not just >> edges). Malcolm Rockwell wondered about the possibility of >> "finger oils transferred when the tape was being inserted in the >> clamshells". Lots of interesting input, and I hope I've credited >> everyone here for these rather relevant ideas. Richard Hess as >> always provided encouragement and ideas. >> >> When I heard "stearic acid" from Ivan, I immediately thought of >> old discs and keeping fingerprints off them for fear of stearic >> and palmitic acid making fingerprints become unavoidably audible. >> Just seemed odd to be looking at cassettes and be talking about >> materials that perhaps threaten certain discs more (maybe only >> because cassette tape is not as easily touched). >> >> Regarding a solvent, yes, I'm very interested in what anyone has >> to say at this point. That list of solvents at the link in >> earlier email is perhaps a conversation starter? >> >> repeated again here... >> >> http://lxsrv7.oru.edu/~alang/onsc/solubility/allsolvents.php?solute=stearic%20acid >> <http://lxsrv7.oru.edu/%7Ealang/onsc/solubility/allsolvents.php?solute=stearic%20acid> >> >> (stearic acid solubility in various solvents, clean up clues) >> >> -Karl >> >> On 10/23/14 8:39 AM, Steve Greene wrote: >> >> 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] <mailto:[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://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 >> <http://lxsrv7.oru.edu/%7Ealang/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 <tel:607-254-1100> >> >> [log in to unmask] <mailto:[log in to unmask]> >> >> Our Mission: >> To interpret and conserve the Earth's biological diversity >> through research, education, and citizen science focused on >> birds. >> >> >> >> >> -- >> >> Karl Fitzke >> >> Audio Engineer >> >> Macaulay Library >> >> Cornell Lab of Ornithology >> >> 159 Sapsucker Woods Road >> >> Ithaca, NY 14850 >> >> >> 607-254-1100 >> >> >> [log in to unmask] <mailto:[log in to unmask]> >> >> >> Our Mission: >> >> To interpret and conserve the Earth's biological diversity >> through research, education, and citizen science focused on birds. >> >> >> >> >> >> -- >> Karl Fitzke >> Audio Engineer >> Macaulay Library >> Cornell Lab of Ornithology >> 159 Sapsucker Woods Road >> Ithaca, NY 14850 >> 607-254-1100 >> [log in to unmask] <mailto:[log in to unmask]> >> Our Mission: >> To interpret and conserve the Earth's biological diversity through >> research, education, and citizen science focused on birds. > -- Karl Fitzke Audio Engineer Macaulay Library Cornell Lab of Ornithology 159 Sapsucker Woods Road Ithaca, NY 14850 607-254-1100 [log in to unmask] Our Mission: To interpret and conserve the Earth's biological diversity through research, education, and citizen science focused on birds.