Is there a reason that selenium toner needs to have fixer in it? Would it be possible to make selenium toner in some other sort of solution that would not bleach? I'd love to have it as an alternative to gold or palladium toners for lower cost and another choice on tone.
Originally Posted by JG Motamedi
Thanks for the lead on less-expensive gold chloride. It's been a while since I toned my prints in gold. Like everybody else, I have been deterred by the cost. Plus the fact that the toner itself is very short-lived, and demands that the printing workstream be built around optimizing the use of the gold toner.
Originally Posted by Mark Fisher
First of all, let me say that my understanding of photochemistry is nowhere near that of some of our members, so I can only guess at the reason. I suspect that the inclusion of thiosulfate in off-the-shelf KRST is a form of insurance against getting inconsistent toning results and staining in prints.
I think that using KRST in toning prints (silver gelatin primarily) involves two simultaneous processes similar to that of monobaths in film developing. In monobaths, the developer acts on the exposed silver, while the fixer simultaneously dissolves the unexposed silver. For monobaths to work properly, a balance must be struck between the speed of development vs. the speed of dissolution of the unexposed silver.
In a KRST solution, the selenium probably works on areas where silver compounds are present the most (shadow densities), and proportionately less on the midtones and highlights. Meanwhile the thiosulfate simultaneously works to remove any "free-floating" silver remaining in the print. If you recall, there is the standing rule that prior to any form of toning, the print should be thoroughly fixed, as well as thoroughly washed. I presume this is to remove all traces of non-image silver, and to remove any compounds formed by the fixing process. The presence of thiosulfate in the KRST solution is probably designed to ensure that the selenium gets to work cleanly.
As an aside: A long time ago while I was working for a media house in Asia, we were able to order selenium powder from a chemical supplier. We would mix a selenium solution and apply it locally to portions of B&W prints with watercolor brushes. The result was the most 3-D B&W prints you ever saw! Prints that were impossible to create by conventional darkroom methods. All this before the advent of unsharp masking or Photoshop.
But since selenium has been classified as toxic (as is many other photography-related chemical compounds), I doubt if it is still possible for individuals to purchase selenium powder to use directly as a toner.
Your answer seems clear and I think the only part of my post you deleted was what I had quoted from your initial posting. Ya gotta watch yourself carefully when you're wielding those "moderator superpowers", kinda like the Charlie Chaplin carrying a ladder. I was just curious because everything I have read suggests that toning first is optimum.
I think the reason you are getting excessive bleach-back is simply the KRST is quite bit more concentrated that necessary. As an example, 1+200 works well on Vandyke (toning times in the 10 minute range and a measureable increase in dmax vs untoned). I know that albumen and VDB sensitizer are not the same but the starting point of the image (silver nitrate) and the root problem (bleach back due to thiosulfite/thiocyante in the toner) are similar. I have used KRST on both Abumen works POP and old studio proof and the problem is similar. I had to give a presentation/demonstration recently, part of which was a toning sequence for VDB. I sifted through my small collection of ancient photgraphic how-to books on the premise that research was the better part of valor when faced with public speaking. What I gleaned from my survey of available literature was: toning first was traditionally done to avoid or mitigate bleach back, and VDB prints do not seem to traditonally have been toned. Anyway, toning first seemed the logical nod to received wisdom and it seems to work well if you get the dilution right. As to economy vs gold toning 5ml/litre really milks a long life out of a bottle of KRST.
Originally Posted by David A. Goldfarb
Sulfide Albumen toning
It is important that you Fix and wash the print before toning with Sulfide toner.
Sponsored Ad. (Subscribers to APUG have the option to remove this ad.)