[QuadList] Toluene

[C. Park Seward]

A couple of points about head clogs.

Oxide and binder comes off tape. Even if you look at an audio machine, you can see oxide/binder on the heads and guides that came from the oxide side of the tape.

We have found that baking the tape (both audio and video) lessens or eliminates oxide and backcoating shedding (SSS - Sticky Shed Syndrome). SSS is caused by absorption of moisture into the binder of the tape, making it sticky.

Yes, you need to clean the heads on a quad to remove the oxide layer. When cleaning, you can see the oxide on your cleaning cloth. The oxide and binder material would short out the gap of the head or lessen its penetration into the tape due to buildup on the head surface.

The official Amex Head Cleaner was made from Xylene, not Toluene.

"The recommended solvent is Ampex Head Cleaner (Cat 087-007) which is composed of 98% Xylene, 2% Trichloretylene and a dash of "Kodaflow", which is a wetting agent intended to enhance the flow of the solvent in restricted areas."

I understand the TCE is to speed up evaporation. I don't remember seeing any other chemical recommended by Ampex. Alcohol was the suggestion for cleaning the pinch roller. 

In modern VTRs like Digital Betacam that uses metal tape, a cleaning tape is necessary to remove metal particles that get imbedded in the heads since regular chemistry will not dissolve the metal particles. Sony recommends using a cleaning tape for five seconds every 50 hours of use.

Tape binders were/are made from polymers like polyvinyl chloride, polyurethane resin and a copolymer of vinylidene chloride and acrylonitrile, polyester urethane and the like. I don't think any tape ever used Latex (rubber) as a binder.

The old "thumbnail" trick on Quad was to loosen any foreign matter and the 14,000 rpm speed of the head would throw it off.

The 3M tape reels that had the foam on one flange had a problem of glue migrating through the foam and onto the tape. The glue did not come from the tape since after transferring the tape to a clean reel, the reel remained clean.

Best,
Park

C. Park Seward
Visit us: http://www.videopark.com




On Jan 14, 2010, at 12:30 PM, georgenann at aol.com wrote:

> I think there are many people who are under the impression that "Head Clogs" come from oxide being stuck in the gap of the heads.
>  
> I'm not sure this is the case.  There may be some instances of this, but one of the common cures for an "On Air" head clog is putting your thumbnail against the head, which works most of the time.  Seems to me that would tend to push anything into the head, not out of it.
>  
> I think it is more a case of the latex binder oozing from the tape and sticking to the head rim, causing "Rim Buildup" and keeping the tape away from the head.
>  
> One of the other "Cures" for this is squirting Freon (TF) into the head while it is running. In this case, Freon is a refrigerant and due to the high speed of the head immediately freezes the latex and it breaks off, there is such a small amount of it you would hardly notice it, thereby relieving the problem.
>  
> This "Oozing" of the latex binder has become quite obvious over the past number of years with the older 2" tapes.  It is all over the place.  In a few minutes of playing a tape, there may be a buildup of this latex on the audio stack, full erase head, (Don't forget that is on the back of the tape) fixed guides and all over the vac cols, stuck to the glass and the entrance and exit guides thereof.  This will cause the machine to just STOP!  This is also a big problem on 2000's and 1200's.  One can actually feel the stuff, even on the head wheel where it causes "Head Clogs". In the AVR-1's one can also feel the stuff on the glass in the vac cols.
>  
> The only thing to do is stop and clean the stuff off of everything.
>  
> Years ago, I thought I would try cleaning it up with some "Rubber Cement Thinner" which had been in a closet in one of the secretary's offices. It did the trick. 
>  
> Later, one of my neighbors who worked for "Tessa Tape" in Middletown, NY gave me some "Toluene" as they use it as a latex thinner in the manufacturing process.  It worked like a charm, it dissolved the damn latex immediately. I was hooked on the stuff. I highly recommend it to everyone.  It won't hurt anything on the machine, or plastic, but I would keep it away from pucks as they are made of rubber.  Also it is a good idea to use it in a well ventilated area
>  
> The best way to clean the pimpled glasses in the vac cols.is to really saturate a cloth with Toluene and wash it out, floating the stuff away.  Also the bottom edges of the entrance and exit guides of the vac cols need to be done with a Q-Tip as small unseen bits of latex like to live in there.
>  
> My test to assure that the latex is completely gone is to thread the machine up, put it in ready and manually turn the capstan both ways.The whole thing, tape, and both reels should move freely, no sticking in either direction and no "Squeaking".
>  
> Now the same problem and Toluene cure applies to everything up to and including the Digibetas.  The U-Matics seem to have a problem with tape coming around the guide inside of the cassette (Just under the cover) causing the tape to either slow down or come to a complete stop.  A little Toluene on a Q-Tip at that guide will amaze you.  I also recommend cleaning the tape guides audio stacks, etc.  on the 1100's and 2000's and for that matter all machines,especially before attempting to adjust the tape guides, you may save yourself a lot of work.
>  
> I understand Toluene may be hard to obtain, as it may be considered a dangerous chemical.  At first I ordered a gallon from Cole-Parmer in Chicago.  They sent it in a glass gallon jug in a cardboard box - Not a good idea.  If someone dropped it they would have had to evacuate the whole building after it got into the air conditioning system.  After that I bought it in pint cans at a True Value hardware store in Pa., right across the river from Port Jervis,NY. as it is a common paint thinner.  (Home Depot doesn't carry it in NY, NJ, or Pa. nor does Lowes.) It only costs about $3.50 or so, not bad for about $500.00 worth of "Ampex Head Cleaner." I have further learned that Pa. is somewhat lax of the dangerous chemicals possibly due to the "Hot-Rod" industry in that state.
>  
> Don't forget what Tri - Nitro - Toluene will do for you.
>  
> One day there was a delegation from Sony in the shop, shortly after the Digibetas arrived, we had a problem with heads and some of the guys were replacing them like hot cakes.  The toluene cured them, but they still wanted to replace the heads, around 5 kb a pop.
>  
> One of the Sony guys was the head of the Sony Tape Plant in Ala.  When I told him about using Toluene, he hit the roof went into a rage about how terrible it was, I was nuts, and on and on.
>  
> I asked him what the Zip code of the tape plant is, and he gave it to me.  Now there is a Web site called "Score Card", in which you put in a Zip code and it will tell you who the polluters in that area are, and what they are polluting with.  Well, it came up with the Sony Tape Plant as being one of the top ten polluters in the country of Toluene. (  http://scorecard.org/env-releases/facility.tcl?tri_id=36301SNYMGHWY84).  I see now that they have changed to Cobalt as their major pollutant, but (http://oaspub.epa.gov/enviro/multisys2.get_list_tri?tri_fac_id=36301SNYMGHWY84) tells me they still spew quite a bit of Toluene into the air. If you think he was mad earlier in the day, you should have seen him after I showed him that. Score Card also showed my neighbor's plant (Tessa Tape) in Middletown, NY also as being in the top 10% of Touluene polluters also.( see  http://scorecard.org/env-releases/facility.tcl?tri_id=10940TSTCKCROTT#major_chemical_releases) The Middletown Tessa Tape plant has since shut down and moved to Ala. because of the pollution laws
>  
> I recall times where there was some "Glue" stuck on the foam rubber liners on some 1" tape reels.  I wonder if this might also be leaking latex binder from the tape, and not the glue holding the rubber to the reels. It has also happened on some 2" reels with that type of liner.  Keeping in mind  the amount of pressure on the wound tape and the position of the "Glue"  (Not on the outer edges of the reel)  this may be the case.
>  
> To top it all off, I was in the "Lab" across the street from CBS in the basement of the same building as Archives is located, bullshooting with one of the "Old Timers" who has been a senior engineer with the labs since before anyone ever heard of video tape.  I mentioned my exploits with Toluene and he was all over me telling me "That's How We Did it Years Ago".
>  
> Was wondering if anyone else has had similar experiences??
>  
> 73,
>  
> George Keller

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