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Thanks for the responses Jim & Dan.  

Good food for thought and experiment.  I do plan to check around to see if some of the alternatives mentioned may be easily obtained in the area to experiment with.  Since I'm dealing with a small number of problem tapes I'll probably keep it up with the alcohol for the time being.  Funny how alcohol will fairly quickly strip the coating off the back but getting a baked on blob, no matter how thin or thick, off the binder side requires much more time and effort.  

I checked out Richard Hess' site also but couldn't find any mention of solvents used for this purpose.  Recommended reading though for just about any subject.  Been a great help to me at various times.

http://www.richardhess.com/tape/

Charles Richardson's Rezerex may have been the back coat stripping service that was featured at a past ARSC conference and may be a practical alternative in some cases.  Seems that they can work miracles with SSS tapes.  The ARSC presentation was certainly informative if not downright entertaining.  They offer a complimentary paper that may be of interest also.   

http://rezerex.com/Publishedpapers.html

Best!  :-)

Martin Fisher

-----Original Message-----
From: Association for Recorded Sound Discussion List [mailto:[log in to unmask]] On Behalf Of Jim Lindner
Sent: Wednesday, February 08, 2012 5:39 AM
To: [log in to unmask]
Subject: Re: [ARSCLIST] Tape Backcoating removal

Yes, another class of solvents that have been used are terpenes and terpanols. The ones experimented were specifically from Eucalyptus, but Tea Tree likely will be worth experimenting with as well. Not only are they solvents  - but they are disinfectants and they leave the room smelling fresh and clean! They are also less robust, but in general for this kind of thing reduced solvent efficacy means more hand work and "polishing" in a process that is already hugely labor intensive. On the other end of the spectrum - a more rough solvent is Xylene, but diluted it might be something to experiment with. As I mentioned this is now a science project. Glad they are not my tapes!



Jim Lindner

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  Media Matters LLC.
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Media Matters LLC. is a technical consultancy specializing in archival audio and video material. We provide advice and analysis, to media archives that apply the beneficial advances in technology to collection management.





On Feb 8, 2012, at 1:18 AM, Dan Nelson wrote:

> A common solvent used in tape binders was MEK (methyl ethyl ketone)   a softer solvent is toluene  which will  wipe the soft back coating that is  loose before it attacks  the oxide. 
> dnw
>  
> Beautiful Music you will never forget, at; 
> http://www.americanbeautiful.podbean.com/
> 
> 
> 
> 
> ________________________________
> From: Jim Lindner <[log in to unmask]>
> To: [log in to unmask]
> Sent: Tuesday, February 7, 2012 9:40 PM
> Subject: Re: [ARSCLIST] Tape Backcoating
> 
> The backcoat binder system chemistry is in most cases similar if not identical to the oxide binder system, so it sounds like you really do have a mess. Removing one without damaging the other will be extremely difficult. It may be that using a pellon wipe to try to remove it not chemically, but through successive wipes at high speed MIGHT remove enough of it to allow playback, but I would have to see it to tell. It also might be that a low concentration of a solvent will remove the "low hanging fruit" first - so again a pellon wipe with a dilution of solvent and water might work - although you then have the rh issues to deal with, which might also cause problems. These are the "fast and cheap" approaches that might work - but then again you have tried fast and cheap already and have reaped the rewards.
> 
> In the past I have used modified film rewinds (with a NAB hub to 
> accommodate tape) and placed the supply reel on one side and the take up reel on the other side - oxide side up in your situation. In between you have your work surface, and you now hand "polish" the tape using a solvent. Unofficially I might suggest experimenting with the now banned 1:1:1 trichloroethane using this modified film rewind approach. Although banned, it may still be available in small quantities from chemistry supply facilities, and yes it is expensive. Fortunately you do not need much. Read the MSDS very carefully, handle very carefully, adequate ventilation, follow all guidelines, hands end eye protection, ventilator - all of it.  This will be a slow hand process. As you get experience you will be able to remove the goo and if you are careful in your application leave the stuff under it. Too much solvent and too much pressure and you will wipe all of it. You "polish" slowly foot by foot winding the completed and clean tape on the take up side. Based on your description you will need to also clean the back coat side because it sounds as if you have softened it enough so that it will reapply itself to the oxide if rewound on it directly based on the pack pressure.
> 
> Yeah, well you really do have a mess and a science project. This is just one reason why I am not a big baking fan. There are not too many cases where I see media that is dumpster bound. Next time you might consider cleaning before baking.
> 
> 
> 
> Jim Lindner
> 
> Email: [log in to unmask]
>     
>   Media Matters LLC.
>   450 West 31st Street 4th Floor
>   New York, N.Y. 10001
> 
> eFax (646) 349-4475
> Mobile: (917) 945-2662
>     
> www.media-matters.net
> Media Matters LLC. is a technical consultancy specializing in archival audio and video material. We provide advice and analysis, to media archives that apply the beneficial advances in technology to collection management.
> 
> 
> 
> 
> 
> On Feb 7, 2012, at 5:18 PM, Martin Fisher wrote:
> 
>> Hey Guys,
>> 
>> What chemicals are good to strip backcoating off reel tapes.  
>> 
>> NO!  NO!  NO!  I don't want to send them out for stripping.  Way too expensive.  I don't even want to strip the entire tape.  
>> 
>> What I need is to clean the backcoat off the oxide layer.  The tape was given a "B" wind after developing sticky shed and, in places, some backcoating "hairs" got stuck between adjacent layers and adhered to the binder.  This was exacerbated further by baking.  The stuff just turned to goo and spread out on the surface of the binder like butter on bread in the oven.  
>> 
>> Alcohol works but also dissolves the binder an many instances.  No way of knowing the tape stock since the boxes are generic, reels are haphazard but the backcoating is of the thick, matte gooeyer variety.  
>> 
>> Any help appreciated!  :-)
>> 
>> Martin
>> 
>