From: Richard Maddox (slow_emulsions@yahoo.co.uk)
Date: 04/29/00-07:10:43 AM Z
Hi Liam,
I just glanced at your note and would like to answer
you in detail. But first, before I reread and address
your letter, may I inquire as to which edition and
page number of Glafkides you are looking at? and yes
The Illford manual ocr would be helpful. I would like
to know the exact name / subname of the manual since
you did not find a date. (There was The Ilford Manual
of Photography pub. in 1944....) anyway, let me reread
your post... and oh, are you just adapting the
information from Glafkides or are you trying to
duplicate a formula presented there?
I will get back with you after I have reread your
note.
RM.
--- Liam Lawless <lawless@ic24.net> wrote:
> Hi Richard,
>
> I've been experimenting with home-made POP emulsion
> for a few weeks, for a
> little write-up for Judy. I've tried a self-toning
> version, without much
> success so far, but have found out a bit about it.
>
> Glafkides says that POP emulsion can be made
> self-toning with 2.5 g of gold
> chloride (AuCl3 he says, though I think he means
> HAuCl4) or thiocyanate per
> 100 g of silver nitrate, added to the gelatin-salt
> solution before
> precipitation. I've tried various proportions
> around that figure, none of
> which seemed to make a significant difference, but
> more than 2.5 g per 100 g
> AgNO3 causes some of the gelatin to coagulate in
> stringy lumps.
>
> An old Ilford Manual of Photography (undated, but
> probably '30s-'40s) has
> quite a bit of info about using POP & self-toning
> papers. The important
> thing, apparently, is that self-toning papers are
> fixed straight after
> printing-out, without an intermediate wash which,
> presumably, would wash out
> the gold. Toning is supposed to happen in the
> fixer. I tried this & did
> not get the staining I half expected, but neither
> did I get any toning. The
> book says that the colour can be varied with the
> strength or temperature of
> the fixing bath, becoming cooler as the toning
> action is stronger. (With
> stronger/hotter fix the density loss is greater.)
> It does not say, though I
> think it probably should, that a wash and fresh fix
> should follow.
>
> With self-toning collodion POP, a salt bath before
> the fixer could also be
> used to vary the tone, but this has little effect
> with gelatin POP.
>
> Maybe my experiments didn't work because I didn't
> use enough gold. I used
> what Glafkides said, but maybe he was referring to
> free silver nitrate, in
> which case more gold would be needed. (But the
> problem with the gelatin??)
> Will try again soon, but what I don't understand is
> how hypo reduces gold
> salts, and only in the image areas at that. Gold
> chloride and hypo together
> form what they used to call gold-hyposulphite, more
> commonly known as sel
> d'or, but if this plays a part in the toning action,
> I'd expect it to
> produce general fog. I've dropped a line to Mike
> Ware, but haven't had a
> reply yet. Any ideas?? And have you got some
> self-toning POP?
>
> If you still need the info, I can OCR it from the
> Ilford Manual. Let me
> know.
>
>
>
> Liam
>
>
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