[alt-photo] Re: Chemical Development for Printing Out Processes

[Ryuji Suzuki]

I've not done this myself but based on what's known about electrochemical model 
of development process, you'll get mostly fog if you process POP material in a 
modern print developer for developed out process.

If you were to adjust formulation for POP, I'd suggest decreasing the developer 
pH significantly, and dilute the developer somewhat. I'd actually use standard 
print developer that's already fully used and exhausted in regular develop out 
printing process, dilute it, and perhaps further reduce the pH by adding baking 
soda or some mild acid.

Historic gallic acid developer is often mixed with some silver nitrate solution 
(so called physical developer). When chemical development process became common 
use, that style of developer went out of fashion. This point is probably good to 
keep in mind when recreating the results of historic literature, but it is 
probably more important to use modern knowledge to figure out what works the 
best for the purpose.

--
Ryuji Suzuki
"No matter how much you study or improve vacuum tubes, you will not arrive at a
transistor." (Leo Esaki)


Francesco Fragomeni wrote:
> Hi all,
>
> It's been a little while since I've last written and I've been kept rather
> busy with my move to NYC but I've been keeping a close eye on the
> conversations.
>
> This question pertains to using chemical development for processes that are
> traditionally considered printing out processes. The literature tells us
> that this was indeed a practiced technique albeit a rare one due to the
> preference of the time for non-black toned prints. One practitioner I can
> reference was the commercial printing operation of Blanquart-Evrard and
> Fockedey outside of Lille, France in the 1850's. They used Albumen with
> chemical development rather then as a printing out process in order to mass
> produce prints quite successfully.
>
> I'm particularly interested in silver-based POP processes like Albumen and
> Collodio-Chloride which make use of silver-chloride as the light sensitive
> agent. The presence of silver-chloride allows the possibility for chemical
> development and I'm quite curious to hear if anyone has experimented with
> this. Apparently, Blanquart-Evrard and Fockedey were able to produce lovely
> grey and black tones by developing Albumen paper (exposed much shorter then
> normally) with a gallic acid based developer. I'm curious what might result
> by developing in modern developers that are established to work quite well
> with silver-chloride emulsions i.e. Amidol, Dektol, etc.
>
> I'm inclined to experiment with this but I'd love to hear about any results
> anyone else has had.
>
> Best,
> Francesco Fragomeni
> www.francescofragomeni.com
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