John, of Frank’s Kitchens. Selenium toned kallitype on Arches HP 140#.

I’m understanding selenium toning a little better as a result of this week’s PrintFest. Selenium and Kallitypes don’t get along very well generally. And now I understand why.

The sensitizer for kallitypes is Ferric Oxalate and Silver Nitrate. Usually, conversations about failures with kallitypes center around the ferric iron being reduced to ferrous iron from exposure to UV light – but with selenium toning, it’s actually about residual silver nitrate. With a typical kallitype print, the residual silver nitrate is along for the ride until the final bath of sodium thiosulfate (“fixer”), with toning happening before the fix. But if you do that with a selenium toner, the selenium and the silver nitrate will react quickly to stain the heck out of the print.

Which means that, prior to toning, the print has to be fixed in order to remove the excess silver nitrate.

There’s a delicate balancing act to be done, though. Too much initial fix will slightly bleach the print, and will reduce the future reactivity of the selenium toner.

This print was fixed for a minute, and then stuck in a selenium bath to partially tone for 10 minutes. It came out pretty much the way I envisioned it. Longer toning should have resulted in a more black (well, gray) print.