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

[Richard Knoppow]

----- Original Message ----- 
From: "Francesco Fragomeni" <fdfragomeni at gmail.com>
To: "The alternative photographic processes mailing list" 
<alt-photo-process-list at lists.altphotolist.org>
Sent: Friday, September 07, 2012 9:12 PM
Subject: [alt-photo] Re: Chemical Development for Printing 
Out Processes


> Ryuji,
>
> Thanks for the reply. So your thought is that the higher 
> ph and potency of
> a modern developer (unused) would cause fog in a POP 
> emulsion. Interesting
> and I hadn't considered that but it makes sense as a 
> possibility.
>
> By the way, I'm not particularly interested in recreating 
> the results of
> historic literature or figuring out what works best for 
> the purpose, hence
> the question about using modern developers with POP 
> emulsions. Its a
> mismatch intentionally. My interest is simply in seeing 
> what the results
> might be simply for the sake of curiosity.
>
> Has anyone actually tried this who can confirm Ryuji's fog 
> hypothesis? Or,
> do any of you Albumen practitioners have an extra test 
> strip and some
> Amidol or other print developer sitting around that you 
> can test with next
> time you print? I'm still setting up my space otherwise 
> I'd try it.
>
> Thanks for contributing Ryuji and anyone else who chimes 
> in.
>
> -Francesco
>
     Perhaps Ryuji can explain the differences in developing 
out and printing out coatings.  I have only a little 
understanding of this but I believe POP coatings do not 
allow the developer to discriminate between exposed and 
unexposed silver crystals, at least not very much.
     The usual process for POP whether gelatin-silver or 
salt or albumin is to allow light generated silver to form 
and then intensify it using a suitable toner.  The unused 
silver halide is removed either co-incident with the toning 
or afterward.  Some toners are not suitable because they 
will tone all the silver regardless of whether it in 
metallic form or not. Here again, I am not sure I understand 
why a gold toner, for instance, will tone an unfixed POP 
print while something like a sulfiding toner will simply 
turn the whole thing to silver sulfide.  Fixing before 
toning tends to remove the image silver along with the 
non-metalic silver, perhaps because it is so fine.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com