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<div><FONT face="Courier New">I kind of remember being told that at the Ampex tape plant about 100 years or so ago, or was told that somewhere along the line. That's one reason I tried the rubber cement thinner in the first place. And everything seemed to fall in place.</FONT></div>
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<div><FONT face="Courier New">I appreciate the chemical info, but not based in chemestry it won't help much. I wonder just what all the freon will do to you, CBS used about 5 gal every couple weeks.</FONT></div>
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<div><FONT face="Courier New">I was very careful when using toluene around plastics, especially the tape cassettes, I experimented a good bit. It didn't seem to hurt it at all. There may be some plastics which it will damage.</FONT></div>
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<div><FONT face="Courier New">I have always been affraid of MEK, have been told many times, including by the Navy which banned it many years ago.</FONT></div>
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<div><FONT face="Courier New">Mny Tnx for the input.</FONT></div>
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<div><FONT face="Courier New">George</FONT></div>
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<div style="FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: helvetica,arial">-----Original Message-----<br>
From: Tim Vitale <tjvitale@ix.netcom.com><br>
To: 'Quad List' <quadlist@quadvideotapegroup.com><br>
Sent: Thu, Jan 14, 2010 7:03 pm<br>
Subject: Re: [QuadList] Toluene<br>
<br>
<div id=AOLMsgPart_0_0e31b08f-ec2b-477d-9b88-90c23061a8ab style="FONT-SIZE: 12px; MARGIN: 0px; COLOR: #000; FONT-FAMILY: Tahoma, Verdana, Arial, Sans-Serif; BACKGROUND-COLOR: #fff"><PRE style="FONT-SIZE: 9pt"><TT>How did you identify the binder as latex rubber?
Later videotape (1/2" R-2-R and later, for sure) used polyurethane as
the medium for the magnetic pigment (that what it's called) on an
cellulose acetate or polyester base. Polyurethane degrades by
breaking off small chains (under acid hydrolysis) of the long urethane
polymers, which clump together as "gunk" that was known as the Sticky
Shed Syndrome. There will be magnetic pigment particles in the
"stuff" stuck to the head, cap stands, guides and wheels. The "stuff"
should be nicely soluble in toluene. However, toluene is quite toxic,
especially if you get it on your skin. Toluene is a benzene ring
(cancer causing) with a methyl group (CH3) on one of the six carbons
in the aromatic ring.
As a conservator with some age on me, I have been guilty of doing what
you have done, and of holding your views. We had a number deaths in
the field years ago that were attributed to solvent use, however, not
just toluene use. We, and I, are much more cautious now. Toluene
does work its way out of the systems in time
<A href="http://en.wikipedia.org/wiki/Toluene" target=_blank>http://en.wikipedia.org/wiki/Toluene</A>, but it is one of the slower
ones, if memory serves.
I'd use a solvent that does the job (maybe not as quickly or with more
elbow grease), but is less toxic, or one that is more easily removed
by the body's defenses. I'd try acetone first, then methyl ethyl
ketone (MEK). They are both in the ketone group, which our body makes
when burning fat under a low carbohydrate diet; you know, ketosis. You
can find all the above solvents (and many more) at Home Depot; even
toluene. They generally run about $4-7 per quart.
There is a complex Teas solubility process that is used to estimate
solubility. I can walk you through it, if you like. I'll have to fax
you some charts and diagrams.
BTW, toluene will go after quite a few plastics. I would not consider
it safe for plastic-laden equipment. Alcohols (specifically,
propanol) are generally the only solvents that get a pass for use on
equipment.
Best of luck...
Tim Vitale
Paper, Photographs &
Electronic Media Conservator
Digital Imaging & Facsimiles
Film [Still] Migration to Digital Format
Digital Imaging & Facsimiles
Preservation Associates
1500 Park Avenue
Suite 123
Emeryville, CA 94608
510-594-8277
510-594-8799 fax
<A href="mailto:tjvitale@ix.netcom.com">tjvitale@ix.netcom.com</A>
Vitale bio
<A href="http://videopreservation.conservation-us.org/tjv/vitale_1pg_bio.pdf" target=_blank>http://videopreservation.conservation-us.org/tjv/vitale_1pg_bio.pdf</A>
Resume: see link in lower right corner of the URL above.
Albumen Photography Website in 2000
<<A href="http://albumen.conservation-us.org/" target=_blank>http://albumen.conservation-us.org</A>>
VideoPreservation Website in 2007
<<A href="http://videopreservation.conservation-us.org/" target=_blank>http://videopreservation.conservation-us.org</A>>
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