Selenium toner replenishment
How does one replenish selenium toner?
If you tone by inspection, it isn't all that critical. I just add a little. If I get the results I want in reasonable amount of time, it is OK. If it is too fast, I add more water. Too slow, more selenium. It is hard to say x number of prints since dark prints use way more selenium than lighter prints. There is a precipitate that builds up that you do need to get rid of either by filtration (coffee filter) or by decanting the liquid.
Originally Posted by Mark Fisher
This is exactly what I do. I keep two solutions, one stronger and one weaker for different papers. Both my gallon jugs have been going for close to 10 years now. My last toning session (36 11x14 prints) did not even require me to replenish.
A comment on "time-toning" using selenium: I see lots of references like, "tone for 5 minutes at 1+19" or the like. Even if one uses the same paper all the time, toning this way will not yield consistent results.
Every print through the toner weakens the toning solution somewhat and slows the toning process for subsequent prints. As Mark points out above, denser prints take more of the active toner out of solution than lighter ones, so this is not even predictable. Also, I find that the right toning for any particular print is individual to the subject matter and the distribution of tones in the print. Visual evaluation of the toning process is the only reliable way to go. Use lighting that you would display the print under.
I like to keep toning times above three minutes because I think that shorter times may lead to uneven toning, so I adjust my toner dilution to give me an approximately three+ minute toning time. As more prints go through the toner, it takes longer and longer to get the same effect. I replenish when toning times become uncomfortably long. For me, this is at about the 6-8 minute mark.
My experience is a strong fast selenium toner definitely can lead to uneven toning, but I quite like the effect it can bring if you get the snatch point right.
I think that shorter times may lead to uneven toning
I have a 500ml bottle that is diluted 1:30, and I haven't used it very much. I've toned an 8x10 and maybe 15 or 20 small test prints. The small test prints are quite small, like 4x6 or even smaller. I noticed that precipitate after a while. Little dark specks. What causes it? I got the impression the precipitate formed even when the toner was just sitting in the garage not being used.
Originally Posted by Mark Fisher
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Thank you for your comments and advice. I tone for protection and change in Dmax. And I tone primarily Ilford MGIV fiber paper. I can discern very little change while toning but notice a change after washing and drying the prints. At my skill and production level I think I need to use time in the toner as my guide.
I have a 5 lit jar and after each session I just top off with the same dilution (1+9).
I never have to fill the processing bath with more than 2 lit, and each time I filter the used part with a traditional coffee filter when pouring it back in the jar.
The larger the total volume, the better it keeps. I started that 5 lit in 2005, in all these years, the total volume might have been renewed at least once.
Even when the jar turns grayish-black, it still works good, but do filter the used part before storing, and when you have the time, once in a while, filter the whole volume!
"...If you can not stand the rustle of the leafs, then do not go in to the woods..."
(freely translated quote by Guido Gezelle)
PS: English is only my third language, please do forgive me my sloppy grammar...
You should be able to see a change in Dmax. Keep an untoned wet print handy for comparison. There's no way to just use dilution and time with selenium toner accurately unless you plan on discarding the toner well before its exhaustion point has been reached; both uneconomical and environmentally irresponsible IMHO.
You could devise a test for replenishment by using exposed strips and comparing tone change; too little change in a given time, replenish a bit, too much, dilute a bit... But, I say again, visual evaluation of the print is going to be your best bet, regardless of your level of experience.
The precipitate, I believe, is caused by selenium plating out on silver thiosulfate compounds that are dissolved in the toner. This can happen long after the last toning session. The precipitate can be easily filtered out using coffee filters, etc.
I have not been able to determine and real difference in a print toned for a shorter time in very strong toner and a print toned in a weaker dilution for a longer time. The tone change just takes longer to achieve in the latter case, giving more control and avoiding uneven toning... Try toning a print in strong toner and then the same print in weaker toner until it matches the first one and see if you can see a difference. I couldn't.