RE: Silver chloride contact printing papers - not AZO

Richard,

One place that has instructions is Clerc, who says:

"Gelatino-bromide or gelatino-chloride development papers, which, for
one reason or another, have become unsuitable for their proper purpose,
may be converted into print-out papers by soaking them in a weak
solution of silver nitrate (about 0.5 oer cent) or in a solution of a
reducing substance such as sodium or potassium nitrite (about 5 per
cent), salts of hydrazine, various developers, sodium sulphite, stannous
chloride, etc.

"After soaking for some minutes, the paper is placed to dry in the dark
without any preliminary washing. The same treatment can be applied to
negative plates or films.

"The method of using is the same as for gelatine print-out papers."

Well, I tried once with 0.5% silver nitrate and (probably) a
chlorobromide paper. As I recall, the silver bath had no effect at all,
compared with an untreated sheet. As I understand these things, the
free silver nitrate permits much greater image densities from printing
out, by combining with the halogen liberated by light exposure of the
original silver halides to form more silver chloride or bromide as
printing proceeds. I'd hazard a guess that the problem is that the
original silver salts of the development paper just aren't sensitive
enough to UV, their speed in this respect (I guess) having been
determined by the emulsification process. Maybe develop-out papers were
different in Clerc's day, but it might be interesting for someone with
time on his (her?) hands to try again with a developer.

Liam

-----Original Message-----
From: Richard Knoppow [mailto:dickburk@ix.netcom.com]
Sent: 29 January 2004 00:28
To: alt-photo-process-l@sask.usask.ca
Subject: Re: Silver chloride contact printing papers - not AZO

----- Original Message -----
From: "Judy Seigel" <jseigel@panix.com>
To: <alt-photo-process-l@sask.usask.ca>
Cc: <alt-photo-process-error@sask.usask.ca>
Sent: Tuesday, January 27, 2004 10:26 PM
Subject: Re: Silver chloride contact printing papers - not
AZO

>
>
> On Tue, 27 Jan 2004, Richard Knoppow wrote:
> >
> > There is another silver chloride contact paper besides
AZO... It's
> > the Centennial Gelatine Chloride Printing-Out Paper sold
in this country
> > by Chicago Albumen works.
> >
> > Judy, its important to distinguish between printing
out paper and
> > developing out paper. Centenial POP is a printing out
paper, Azo is a
> > developing out paper. While both have silver chlororide
in their
> > emulsions (I am assuming this about the Centenial paper)
the emulsions
> > are otherwise different.
>
> Yes, of course... I'm quite aware that Centennial is a
POP, in fact I said
> so. And am now editing details of just how to POP it, of
which god is in
> the toning.... (If the original query specified
*developing out
> paper* I missed that....)
>
> However, speaking of image color, the Centennial
apparently gets a neutral
> or cool tone with the thiocyanite formula for the gold
toner... and of
> course platinum toning is also cool.
>
> I'll add, though that DOP can be made into POP with a
chloride bleach...
> I think Chris Anderson, or maybe it was Liam, or both(?)
have done that
> too... You bleach it back with hydrochloric acid & (as I
recall) a
> bichromate bleach... and just leave it in the sun or
strong light and
> forget about it... You think nothing is happening, but in
a few days you
> have a brown tone quite tactile photograph. Could
probaably gold tone it
> too, if you felt the urge.
>
> J.
>
  Somewhere, in the all too distant past, I also had instructions for
making POP out of DOP. Mainly I remember that it was treated in a
solution that included silver nitrate. I can no longer remember where I
saw this but have a vague clue that I can follow up.
  The color of the image on B&W paper is mainly controlled
by the nature of the silver particals making it up. Printing out paper
has extremely fine grains which tend to look redish or yellowish. After
exposure to the sun the paper has a maroon color. However, the image is
not permanent so must be treated with a toner and fixed. The final color
will depend on the toner. Gold toners leave a blue black or purplish
image color. Platinum a neutral black color. There are other toners but
I think these two are the only ones widely used. I think Selenium can be
used to tone POP but Kodak Rapid Selenium Toner has thiosulfate in it
and will tend to bleach the image before its toned. A POP image can be
fixed before toning but the fixer will tend to dissolve some of the very
find metallic silver image as well as the excess halides, so the usual
procedure is to tone first in a toner which is selective for metallic
silver and not the halide. That leaves out sulfiding toners off all
varieties because they will tone the halide as readily as the silver.
  There are lots of toner formulas for POP in old books, but
as is often the case with ancient art, they must be taken
with some skepticism. You have written about such
precautions in using old formulae and procedures youself, so you know
what I mean:-)

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com