[pure-silver] Re: Toner for chocolate brown tone
- From: Jeffrey Thorns <puresilver@xxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Thu, 15 Feb 2007 18:37:45 -0800
Up to 240 grams per liter? Isn't that kind of a lot?
Ryuji Suzuki found a patent issued to Ira Current who was
Ansco/Agfa's toner expert. The patent is for "Cold Sepia Tones". In
it he shows that a very large amount of Potassium Bromide in the
developer will cause the toned image to shift from red to blue. This
is about the opposite of the conventional wisdom but he shows
spectrograms of the reflected light to prove it. The patent is:
USP 2,607,686
Current gives two developer formulas. One is special but the other
is Agfa/Ansco 103, a cold tone developer originally for contact
papers. It is similar to Kodak formula D-73, slightly more active
than Dektol/D-72. One could get about the equivalent by adding about
10 grams/liter of Sodium Carbonate, monohydrated to Dektol/D-72 and
then adding the bromide.
Current specifies adding Potassium Bromide, 60 to 240 grams per
liter to the stock solution. The normal developer has about 2
grams/liter of Kbr.
The developer stock was diluted normally, that is one part stock
to 2 parts water. Prints were developed up to 10 minutes. Current
states he toned in both a Liver of Sulphur toner (Kodak Brown Toner)
and in a bleach and redevelop ("indirect") sepia toner. The color of
the toned image varies with the amount of Bromide added to the
developer.
I think this is at least worth a try.
You can get any United States patent from the Patent office site
at http://www.uspto.gov You will need a plug-in to see the FAX
tiff files. The best is Alternatiff, which is free ware and
available in two forms, one for Internet Explorer and the other for
Firefox and other browsers not using Active-X.
You can also find patents on the Google Patent site at
http://www.google.com/patents
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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