Here is the surprise: the dilution of the Glyoxal has a very real effect on
how my paper clears. I tried it at 50ml per liter, 35ml per liter, 25ml
per liter (what had been suggested to me),19ml per liter, and without
hardening. All tests were "hardened" for 10 minutes at room temp (75
degree F). Both the 50ml and the "without hardening" tests were badly
stained. I should have tried another test at 12ml per liter, because the
19ml per liter was the best test. The differences in the 35, 25, and 19
are small when used with transparent watercolors. They are significant
when tested with two different brands of gouache. The 19ml per liter
sample not only cleared the best, but had better definition between the
steps of my test wedge. I also tried 25ml and 50ml on Rives BFK (before
settling on the Lana paper). Again the 25ml was much better than the 50ml
test.
I realize that gum can be (is?) a frustrating process to make generalities
about. What works for one person, doesn't for the next? Why do prints
clear in almost 1/2 the time at my friends studio across town, compared to
my own darkroom??? And of course we have so many different materials being
used (gloy, glues, watercolor paints, acrylics, HELP!!). But here are my
two suggestions:
1: If you are using hardened gelatin as a paper size, try Glyoxal.
2: Experiment to find the best solution percentage, less may be better.
tomf2468@pipeline.com (Tom Ferguson)
>I'm back to doing some gum prints (after a 2 or 3 year break), and
> just about to run out of my old supply of 37% formalin. Nasty smelly
> stuff that it is! I was using it 25ml per liter of water to harden 200
> bloom gelatin.
>I've ordered some glyoxal from Bostick and Sullivan to replace to
> formalin. Any suggestions on concentration and/or procedure?