[pure-silver] Re: Chemical Fogging in Reversal Processing


Hi John,

I don't think that the science of chemical fogging for B&W reversal has advanced too much since Grant Haist wrote his book, but there may be "variations on a theme".

For what it's worth, I do chemical fogging with an alkaline thiourea bath (the "odourless" version of an alkaline sodium sulfide bath). It works quite well. The image tone depends (to some extent) on the alkalinity of the toning bath as well as on the grain structure of the film (in my hands, TMX gives a sickly yellow colour, while Pan-F+ gives nice chocolate brown tones).

Jordan

John Banister wrote:
Hello,

I'm wondering if anyone has any experience they'd care to relate
about reversal processing of black and white film, and in particular
about using chemistry rather than light to fog the emulsion either as a
separate step or by using a fogging developer.

I've asked related questions of a couple of list members via private
email and on their recommendation I've obtained Grant Haist's two volume
book, _Modern Photographic Processing_. Chapter 7 in volume 2, "Reversal
Processing of Black and White Materials," answered any questions I had and
several I hadn't considered to ask. Since I have also often learned the answers
to questions I hadn't considered to ask by reading of the experiences of
others, I thought that I'd ask y'all if anyone has any B&W reversal processing
experiences you'd care to tell about. I've searched for reversal related posts
in the archives, but found little in the way of related experiences with
deliberate chemical fogging as part of reversal processing. I'm aware that it's
often recommended to use light for the fogging, but I have the notion that with
chemistry I could eventually learn to program it all into my autoprocessor once
I have a method that works.


It'll probably be a year or so before I'll actually be doing reversal tests
with film, so please don't consider that I have any immediate need.
I'm still gathering information and letting it percolate in my mind.
Thanks for taking the time to read these words.

John Banister


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