I’ve noticed that the first three or four prints take quite a long time when using selenium toner, but the next ones take much less time. (About 3–4 minutes compared to 45 seconds.)
Is it just my imagination? Or does selenium toner work faster the more it’s been ‘used up’?
Something’s not quite right here. Basically, it’s as Franz describes. The toner gets faster as the pH drops and eventually flips completely: the selenium precipitates out, a black residue remains in the bottle or tray, and the fun is over. That’s why, for example, it’s not a good idea to keep adding acidic fixer bath residues to the selenium toner. I once had a bit of fun adding different amounts of sodium metaborate to the toner, which resulted in the pH stabilising at different levels in the alkaline range. The toner becomes painfully slow as the amount increases and is practically dead at 10g/l. At 1g/l, however, the toner is only minimally slowed down and sufficiently stabilised. My problems with selenium toner tipping over have been a thing of the past ever since.
As for your specific case: Which fixer, and how is it used? What temperature is used during toning?
If you use an acidic fixer, an alkaline intermediate bath helps. That, and nothing else, is incidentally the reason why Ansel Adams recommended a pre-bath in Kodak Hypo Clearing Agent and, for a time, adding it to the toner! Residual thiosulphate in the paper doesn’t matter with selenium toner, as it contains thiosulphate itself. Above all, the paper should not be acidified and no acid should be carried over into the toner. Alternatively, you can simply rinse the paper thoroughly. That’s not quite as good, but as your toning otherwise works well enough, it should suffice.
However, that might not be your problem at all. If you don’t control the temperature during toning, such variations can also occur.
Otherwise, as Franz already wrote: wear gloves, work cleanly, rinse thoroughly.
Best regards
Stefan
