update on white scum from viradongreenspun.com : LUSENET : B&W Photo - Printing & Finishing : One Thread
i posted a question a couple of weeks ago about a white, scummy residue from agfa viradon. i think i may have stumbled upon the cause: oxidation of the toner. i noticed that the scum showed up on trays after they'd dried, even if i'd washed them really well. to test my theory, i toned a print and then just left it exposed to the air in a dry tray for a few minutes. it was covered with the scum after about five minutes. i then toned some prints, and made sure i agitated them really well and minimized exposure to the air. no scum appears to have affected them, but i won't be able to tell for sure until they're dry.
-- brad daly (email@example.com), June 20, 2000
After toning, immediately immerse the print in a sodium sulfite HCA bath, then wash etc as normal.
-- John Hicks (firstname.lastname@example.org), June 20, 2000.
Hmmm, can it be so that the white scum comes from a gas after a reaction with the fix residues in the papers?
-- Patric (email@example.com), June 20, 2000.