Developing ultra low ISO films for direct duplicating

Yezishu said:

0.5g of ferric nitrate speeds things up noticeably; two more spoonfuls makes it even faster. Cerium ions don’t show much color, so I just rinsed briefly with sodium bisulfite. If you use a lot of iron(III) ions, EDTA may be needed to prevent iron(II) ionsresidue and subsequent discoloration.
If the speed is too slow after using, it might be due to not enough sulfuric acid—some free acid is needed to solve silver. Glafkides’ original formula may not have enough sulfuric acid, which limits capacity (and he got the valence wrong in his book). A little cysteine might also help, but I haven’t compared yet.

Click to expand...

Raghu Kuvempunagar said:

Thank you. How long does your bleach remain active and useful after adding Ferric Nitrate? And do you replenish the bleach with Sulphuric Acid and/or Ferric Nitrate everytime it is reused?

Click to expand...