I'm sure Keith will answer your questions directly, but as I use the same
method I thought I'd add my 2 cents...
The dichromate method is infinitely variable. The six bottles outlined
in the book are approx. "1 contrast grade" apart, but you could make any
grade in between as well. From my experience, I would not recommend
using anything above "grade 5" as outlined in Arentz' book. Higher than
grade 5 can cause grain problems.
As far as I can tell the solutions keep indefinitely without serious
degradation. You should be able to establish a chart of density range
vs. developer grade.
Another thing I have found, particularly when using the higher grades of
developer, is that vigourous agitation of the print in the developer
seems to bring out more subtle highlights with fewer grain problems.
This may be because (and I'm speculating here now) the dichromate acts as
a restrainer. Subsequently, the development time increases with each
increase in developer grade. Since the highlights develop less
vigorously, the paper fibers have time to swell, and the undeveloped
emulsion gets washed away a bit, etc. leading to grain. By vigorously
agitating the print, I believe that the whole print develops more quickly
and therefore results in less grain. Of course, I could just be full of
beans. :)
As for health hazards, sodium dichromate is *really* nasty stuff. Very
toxic. Use this material with extreme caution. Wear eye protection and a
dust mask when working with the powder. Avoid the fumes as much as
possible. The developer solution is friendlier since such scant amounts
of dichromate are used (i.e. a normally well ventilated work area should
suffice). Some people prefer to use ammonium citrate because it is
non-toxic. However, once you've used it to develop prints it becomes
toxic. So...if you're going to put it on a shelf and admire it, great,
but if you're going to be developing prints, I think the potassium
oxalate/sodium dichromate is fine provided it is used with the standard
precautionary measures - well-ventilated area, etc. I also use tongs.
I use Kodak Hypo Clearing Agent to clear my prints with great success.
Good luck.
David Fokos