Selenium Toner question

[Oren Grad]

FWIW, I routinely test my prints for residual hypo and residual silver compounds (HT-2 and ST-1 tests respectively). I test the last print through a batch of fixer almost every run. My prints never have even the slightest stain, so they're passing the tests with flying colors. I've been toning this way for 15 or more years, testing as I go and have never had a problem.

With rigorous testing like that you should be fine indeed. I don't think there is anything more you could reasonably do.

[Doremus Scudder]

Owen,

Testing isn't really that difficult. I have the solutions on-hand and just put a drop of each on the margin of last print of a run through the fixer, wait three minutes and check for stain. Then it's back in the wash for a few minutes to wash out the chemicals on the margin. EZPZ.

FWIW, you can use KRST 1+9 instead of the ST-1 (which doesn't keep quite as well). I test out of habit; I'm pretty confident that I'm using my fixer wisely (i.e., two-bath and not to capacity) and washing long enough.

Back to the toner: as long as whatever is in the toner that's not toning the print washes out, there should be no problems. Insoluble silver compounds in the toning bath would precipitate out if they were ever formed. If prints are well-fixed before hitting the toner, there shouldn't be any carry-over of unfixed or partially-fixed thiosulfates to the toning bath in the first place.

Best,

Doremus

[Joe O'Hara]

Thanks Doremus, it sounds like as usual you've thought this through very well.

When I finally decide to start over with a new batch of KRST, I dump it into the same bucket that I dump
my used fixer. That bucket has a couple of pieces of steel wool in it to (it is hoped) scavenge the silver from
the fixer before it gets into my septic system. I figure the selenium in the old toner will plate out on the silver
that has plated out on the iron, but I'm not a chemist. After a week or three down the pipe it goes.

Based on what I've read here, I'll just keep on filtering the KRST solution and replenishing it as needed. It does
seem to work fine once I've gotten all the crystals and sludgy bits out of it. At my rate of usage I'll never need
to buy another liter of concentrate again.

[esearing]

For archival protection I remember reading a scientific study/article that proper washing and mounting protected the image more than selenium alone. It suggested that "pollution" from the rear of the image and interaction with the paper was more damaging than the silver/emulsion surface.