pH of developer, was RE: Another Ziatype question

Just wanted to again emphasize the importance of keeping the
developer acidic in ferric oxalate based iron processes, specifically
kallitype and palladium printing using sodium citrate developer but I
suspect that the same would apply to ammonium citrate with both
processes as well.

I had noticed over the past two weeks or so a loss of Dmax density in
both my palladium toned kallitype and palladium work, using 30%
sodium citrate developers, and found that they were quite alkaline,
ranging from about 7.4 up to 7.8. I added a couple of teaspoonfuls of
citric acid per liter of developer and brought the pH down to about
6.4. Dmax increased by about log 0.20 to around 1.50 with both
kallitype and palladium, with no other change in procedure. This was
on Stonhenge paper, no oxalic acid soak, but double coating with both
processes.

Sandy
Received on Wed Oct 13 19:22:49 2004