[pure-silver] Re: Sepia toning & Potassium Bromide & Ira B Current
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Mon, 5 Nov 2007 12:55:12 -0800
----- Original Message -----
From: <C.Breukel@xxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Monday, November 05, 2007 5:13 AM
Subject: [pure-silver] Sepia toning & Potassium Bromide &
Ira B Current
FYI
Some weeks ago Richard posted below comment on the list:
A curiousity pointed out to me by Ryuji Suzuki is a
patent issued to Ira Current of Ansco for warm tone
developer USP 2,607,686. Current found that adding very
large amounts of Bromide to an active developer made sepia
toned prints cold sepia. This might be worth a try. One of
the developer formulas in the patent is essentially the same
as Dektol. Current added from 20 to 80 grams of Potassium
Bromide to this. From the patent data the development time
will be much increased, perhaps 8 minutes. See the patent
for more data. Most of the literature will lead you to
believe that adding Bromide will result in yellower tones
from sulfiding toners. According to this patent this is not
true _if enough bromide is added_.
I picked up the patent, and got the impression (perhaps
wrongly) that
when you would use one of the described developers with
increasing (big
amounts) of KBr one could obtain warmtone/spia tones out of
a regulair
cold tone paper.
I tried on Ilford MG IV RC with below developer:
Metol 5 gr
Sodium sulfite 40 gr
HQ 6 gr
Sodium carbonate 50gr
In 1 liter, with increasing amounts of Kbr from 25, 45 to 64
grams per
liter.
Therewas no change in image tone, nor were the developing
times longer
than normal.
Re-reading the patent I think it was more wishfull thinking
on my side.
Maybe I'll re-try on Kentmere Kentona, and than tone with a
polysulphide
toner afterwards,
Best,
Cor
I'm not quite sure what Current had in mind but I suspect
it was getting acceptable tone on warm tone paper when using
indirect type sepia toners. As you know the image color of a
paper when toned is affected by its image color before
toning. Warm tone papers tend to produce yellower colors
than cold tone papers. The usual type of indirect toner
(bleach and redevelop) tends to produce more yellow tones on
any paper than direct toners (like Hypo-Alum or Polysulfide)
so its useful for cold or neutral tone papers but may be too
yellow for warm tone papers. I think Current may have been
aiming at these papers but that's only a guess.
There certainly differences in the emulsions of a lot of
modern papers as is indicated by the difficulty of bleaching
them in some of the standard Sepia toners. Kodak Sepia Toner
II appears to have been designed to overcome this problem.
Dave Valvo, who formulated it, is on this list and can
provide more accurate information than me and also may
understand Current's patent better.
My point is that Current's patent may not work on modern
papers.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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