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Author Topic: Film Chemistry Question
Ed Inman
Expert Film Handler

Posts: 101
From: Jackson, Mississippi USA
Registered: Jul 2004


 - posted 06-28-2006 03:51 PM      Profile for Ed Inman   Author's Homepage   Email Ed Inman   Send New Private Message       Edit/Delete Post 
I suppose this question is unusual but since several people here are associated with Kodak, various film labs, etc., I thought someone might have an answer.

Is there a chemical that will dissolve a silver soundtrack without affecting the color emulsion?

For instance, would a traditional B&W bleach formula such as Kodak R-9 (dichromate and sulfuric acid) in conjunction with a socium sulphite clearing bath successfully remove the silver without damaging the color picture? Or perhaps some other formula I'm not familiar with?

I have an old trailer that was printed on the release stock backwards, i.e. the soundtrack is printed onto the color emulsion and the silver track appears as a dark bar down the right side of the picture.

It won't play at all with an exciter lamp but it plays ok with a red LED Jaxlight. So if there is a way to dissolve the silver without harming the color image I would then have a good trailer.

thanks for any suggestions,

Ed

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Phillip Grace
Expert Film Handler

Posts: 145
From: ACMI. Melbourne. Australia.
Registered: Mar 2004


 - posted 06-29-2006 03:14 AM      Profile for Phillip Grace   Email Phillip Grace   Send New Private Message       Edit/Delete Post 
Hi Ed.
Bleach then Fix should work. You might try your nearest motion picture lab, and see if they would run it through their Positive processing machine. Caution is advised though. You will need to have some idea of the age of the film, as the higher temperatures in the current process may strip the emulsion completely. If you read the specifications of the current Kodak ECP process (ECP 2B?) you will get a good idea of which steps in the process to use.

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000


 - posted 06-29-2006 09:01 AM      Profile for John Pytlak   Author's Homepage   Email John Pytlak   Send New Private Message       Edit/Delete Post 
I agree, running the film through the ECP-2D process again without soundtrack application should remove most of the silver (through the action of the bleach and fixer), although a slight stain may remain. Any print film made for the ECP-2 process is fine, but earlier films were not forehardened, and will NOT survive the hotter ECP-2 process.

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