HP5+ and LONG development times

I am shooting HP5+ in the 8x10 format in a pinhole camera for cyanotypes. I
am having trouble getting the highlights dense enough. I am up to a 20
minute development time now, and still the highlights only have a density of
1.71. I would like a density range of about 1.6, starting at 0.35, say, in
the shadows. (I have to shoot it at like 3200 to get the shadows this
thin!) Should I keep increasing the development times? Is it "bad" to go
over 20 minutes? I process in straight D-76 in a homemade BTZS-style tube,
at 68 degrees. I am thinking maybe I should make the temperature warmer
rather than making the times longer. But, then what will I do if I ever
have to increase the development time further for a low-constrast scene?
(Excuse the cross posting if you read
the pinhole and alt-process lists.)

--shannon
Received on Tue Jul 16 23:54:45 2002