[pure-silver] Re: Sepia Toners
----- Original Message ----- From: "titrisol" <titrisol@xxxxxxxxx> 
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Monday, January 28, 2008 10:37 PM
Subject: [pure-silver] Re: Sepia Toners
Absolutely NaxS (polysulfide) is one of the ways to buy this chemical
The S-2 is the active part that creates Ag2S which is quite stable That is the yellowish "Silver tarnish" in solid silver exposed to atmosphere.
Polysulfide is popularly called "liver of sulfur" and is sold under that name. It is properly potassium polysulfide and is of somewhat indefinite composition. It will work as a redeveloper in place of sodium or potassium sulfide but is not the same compound. Polysulfide toners, like Kodak Brown Toner and Agfa Viradon, have the peculiar property of toning more rapidly as they are diluted or exhausted. This can cause problems when washing since the toner will continue to work in the wash until its is substantially removed from the paper or film. The toner can cause a peach colored stain if not washed out quickly. It is recommended that a "stop bath" of about 10% sodium sulfite (I mean sulfite here) be used as a rinse between toning and washing. The sulfite will also immediately clear the yellow or orange stain remaining after toning. I've found in practice that the sulfite bath does not have to be this strong and Kodak Hypo Clearing Agent at normal working dilution will do nicely. This sulfite "stop" should also be used for polysulfide/selenium combination toners. Normally polysulfide toner is used at elevated temperature (Kodak suggests 100F) to obtain reasonably rapid toning. However, I've found the combination formulas I posted work very quickly at room temperature. Perhaps its the added alkali that speeds it up. Note that _any_ sulfiding toner provides very substantial image protection. So does selenium toner provided toning is carried out far enough. The failure of KRST is only when its used in high dilution (1:19 or more) for short periods as was recommended when image protection without change in color or density was desired. Dr. Nishimura suggests for prints that the toning be carried out at a dilution of not more than 1:9 and for a period of not less than 3 minutes at room temperature. This will result in some change in color or density or both for most papers. KBT will provide image protection if toning is carried out far enough for a visible change although slight. A further note: We have mentioned Nelson's Gold Toner a few times. Nelson's is a variation of a direct toner with the addition of gold chloride as a color modifier. Because Nelson's can generate some halide during toning prints toned with it should be fixed again after toning. If not fixed the residual halides will cause eventual image degradation. When re-fixed they will be as permanent as any other sulfide toned print. Kodak left out the final fixing step in some of its processing booklets. The published instructions for Nelson's are pretty much lifted from the patent which IMO is the best source of instructions for the process. The patent is USP 1,849,245. Any US patent is available from either the US Patent and Trade-Mark Office at http://www.uspto.gov or from Google Patents. The latter offers the convenience of downloading a patent in PDF form rather than as the separate TIFF images from the patent office site. Go to Google and click on the tab marked "more", the patent search is under that, or maybe its "even more". I don't yet have my reference books back so I can't post the published formula for Kodak's polysulfide toner. Again, its not identical to KBT but in practice is the same thing. IPI also published a formula for a polysulfide toner intended for protecting microfilm in place of highly diluted KRST. This uses borax as the alkali and is supposed to have low odor. Other polysulfide toners and, in fact, most sulfiding toners of any sort, have the strong "rotten egg" odor of hydrogen sulfide so they should be used where there is copious ventilation or out of doors. Yet another note: The current instructions for Kodak Sepia II suggest working under a safe-light. The reason for this is that strong light can generate photolytic silver in the bleached image. Photolytic silver is metallic silver generated directly by the action of light on an emulsion. Working under a safelight is probably too fussy but toning, especially in the bleach and redevelop type, should be carried out under subdued light. My source for this is Dave Valvo, a member of this list, who designed Sepia II toner for Kodak. 

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Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx


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