From: Richard Knoppow (dickburk@ix.netcom.com)
Date: 06/22/02-06:28:16 PM Z
At 07:34 PM 06/22/2002 -0400, you wrote:
>Hi Richard,
>
>> Do you want to bleach the silver or the Pyro stain image?
>
>I wanted to bleach the silver and keep the stain, so the method
>mentioned by Liam of combining pot. bromide with pot. ferri. should
>work. However, since there is very little traffic here, if you don't
>mind posting some of the reducer formulas, for example the Kodak
>R-15, I'm sure others will also appreciate it.
>
>Would you by chance have the formula for Kodak Sepia Toner? Seems
>that it should be easy once we have the bleach already.
>
>Thanks for the info, Richard.
>
>Sam
>
Kodak Persulfate Reducer R-15
Super-Proprortional: For Great Reduction of Contrast
Stock Solution A
Water 1.0 liter
Potassium Persulfate 30.0 grams
Stock Solution B
Water 250.0 ml
Sulfuric Acid (dilute)* 15.0 ml
*To make, take one part of concentrated sulfuric acid and with caution to
avoid contact wiht the skin, add it slowly to 9 parts of water with
stirring. NEVER add the water to the acid.
For use: Take 2 parts of Solution A, and add 1 part of Solution B.
Treat the negative in Kodak Special Hardener SH-1 for three minutes and
wash thoroughly before reduction. Immerse in the reducer with frequent
agitation and inspection and treat until the required reduction is almost
attaned; then remove from the solution, immerse in an acid fixing bath for
a few minutes, ans wash thoroughly before drying. Used solutions do not
keep well and should be promptly discarded.
Solution A will keep for about 2 months in a cool dark area.
The diluted Sulfuric acid should last indefinitely.
SH-1 is a Formaldehyde hardener. It may not be necessary. In any case,
here it is:
Kodak SH-1
Water 500.0 ml
Formaldehyde, about 37% by weight 10.0 ml
Sodium Carbonate, monohydrated 6.0 grams
Water to make 1.0 liter
Treat in the hardener for about three minutes. Then rinse and treat in an
acid fixing bath for five minutes and wash before treating in any other
solution.
Kodak Sulfide Sepia Toner T-7a
Stock Bleaching Solution A
Potassium Fericyanide 75.0 grams
Potassium Bromide 75.0 grams
Potassium Oxalate 195.0 grams
Acetic Acid, 28% 40.0 ml
Water to make 2.0 liters
Stock Toning Solution B
Sodium Sulfide 45.0 grams
Water to make 500.0 ml
To prepare the bleaching bath take A, 500.0 ml
Water 500.0 ml
To prepare toner take B 125.0 ml
Water to make 1.0 liter
Treat prints in the bleach until the image almost disappears.
Then rinse thoroughly in cold water and re-develop in Part B until all
image detail returns.
Prints should then be treated in the following:
Kodak Stock Hardener, F-5a 1 part
Water 8 parts
Treat for five minutes and wash thoroughly.
The hardener is at about half the strength it is in the fixer solution
its meant to be used with. Essentially its concentrated fixing bath without
the hypo.
There are many variations of the bleach for this type of toner. They
affect the color of the resulting image to some degree.
According to Kodak, some photolytic silver may be generated after
bleaching so the toning process is best carried out under dim light.
Normal Farmer's reducer does not have any halide in it so the silver is
converted to silver ferricyanide. This is removed by Hypo but may not
develop very well. The presense of a halide (bromide, etc.) is necessary to
insure redevelopability.
All in all I would suggest scanning or copying any valuable negative
before subjecting it to any treatment. Most of them are not completely
predictable.
Grant Haist, in his book on photographic processes, strongly recommends
the use of distilled water to make up toning and similar formulas.
In particular, Iron in the water is devastating to any ferricyanide
treatment.
---- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com
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