[pure-silver] Re: Pre-soaking film
- From: Tim Daneliuk <tundra@xxxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Fri, 30 Apr 2010 07:43:57 -0500
On 4/30/2010 4:04 AM, Richard Knoppow wrote:
>
> ----- Original Message ----- From: "John Stockdale" <j.sto@xxxxxxxxxxx>
> To: <pure-silver@xxxxxxxxxxxxx>
> Sent: Friday, April 30, 2010 1:41 AM
> Subject: [pure-silver] Re: Pre-soaking film
>
>
>> The different formats might come from the same roll in some factories,
>> but the pdf files of specifications for Ilford and Kodak state
>> different thickness of base for 35mm and 120, the latter being a bit
>> thinner. I think that anti halation treatment might be different
>> too, given the different colours of pre rinse water.
>> John
>
> I rather think its not anti-halation dye that you see in the rinse
> water, perhaps sensitizing dye. The dye in the anti-halation backing is
> not removed during processing, rather, it is changed to a colorless form
> (leuco form) by the sulfite in both developer and fixing bath. On of the
> effects of the so-called Vinegar Syndrome, that is the decomposition of
> cellulose acetate (safety film) base is the recolorization of the
> anti-halation dyes. Illustrations of this can be found on the web by
> doing a Google search for "vinegar syndrome". While safety base film was
> thought to be more stable than cellulose nitrate base it turns out that
> its not. Now, some sixty years after the discontinuance of nitrate base
> film the camera originals of many Hollywood motion pictures are just
> about gone due to the base decomposing. It may not present the fire and
> explosion hazard of nitrate but may be even less permanent.
>
>
Well that's depressing news. I planned to live several hundred years
so I could finish printing everything :) Here's a reference:
http://en.wikipedia.org/wiki/Cellulose_acetate_film
--
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Tim Daneliuk tundra@xxxxxxxxxxxxxx
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