I plan to experiment with cleaning up print highlights this weekend via ferricyanide solution & refixing, so I'm googling around for whatever tips I can find. A thread on APUG suggests that this won't work on RC prints, yet another assures that it will. Any comments on this dilemma?
>I plan to experiment with cleaning up print highlights this >weekend > via ferricyanide solution & refixing, so I'm googling > around for > whatever tips I can find. A thread on APUG suggests that > this won't > work on RC prints, yet another assures that it will. > Any comments on this dilemma?
Ferricyanide is used in Farmer's reducer. It will work on any paper or film. There are some variations of Farmer's mainly in the strength of the bleach. Farmer's can be used in two ways: 1, bleach and hypo combined; 2, bleach used first and then the hypo. The first tends to reduce low density areas first, the second reduces more or less uniformly reducing contrast. To clean highlights the first is probably better. After a print or negative is treated with Farmer's it should be re-fixed and thoroughly washed. Farmer's converts some of the silver to silver ferricyanide which will eventually cause a stain if left in the emulsion. It will also tone so reduced prints should be fixed and washed again before toning.
-- Richard Knoppow Los Angeles, CA, USA dickb...@ix.netcom.com
>I plan to experiment with cleaning up print highlights this >weekend > via ferricyanide solution & refixing, so I'm googling > around for > whatever tips I can find. A thread on APUG suggests that > this won't > work on RC prints, yet another assures that it will. > Any comments on this dilemma?
I intented to answer directly about RC vs: Fiber in my other reply but didn't so here goes... It isn't the support but the kind of emulsions often found on "modern" papers, especially variable contrast paper. These are more complex than those found in conventional, graded, papers and may be harder to bleach and to tone using indirect (bleach and redevelop) toners. I am not sure of the exact reason but it may have to do with the presense of silver iodide in the emulson although that is found in much larger quantity in film. In any case the same bleaches, including ferricyanide, will work but may have to be stronger or used for longer. Kodak encountered this problem with their Sepia Toner, a bleach and redevelop type using a ferricyanide bleach, and came out with a new toner, Kodak Sepia Toner II, which differs mainly in the composition of the bleach. It is still a ferricyanide bleach but is stronger. My experience with the older toner on variable contrast paper is that it never quite completely bleached out the shadows, which remained black where older paper was bleached to the point where the image was a yellow color even in the densest parts. While a reducer is not usualy required to bleach to this extent they may take longer to work on variable contrast emulsions. This may not be a bad thing when bleaching for the purpose of removing highlight veiling. Note that the bleach used for reduction is somewhat different from that used for toning or intensification. The former converts the silver to a form that can be removed by hypo while the second converts the silver to a silver halide which can be redeveloped in sulfide or in a conventional developer. The halide can also be removed by hypo, of course, but if that is what is desired the first type works as well and the formula is simpler since it does not require a halide (typically bromide) to be present. As far as the emulsions go there is no difference between emulsions suitable for coating on conventional "fiber" (untreated paper) support and on resin coated paper support but typical RC papers may have newer types of emulsions. Most of the photographic solutions are pretty old. While developers and fixers may work about the same way on both old and new papers some formulas, such as the bleaches used for toners, reducers, intensifiers, etc, may not and need some modification when used on modern materials.
-- -- Richard Knoppow Los Angeles, CA, USA dickb...@ix.netcom.com
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