Re: HP5+ and LONG development times

Shannon Stoney wrote:

> 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.)

While waiting for an appointment I pulled out my alt books for a little
reading. In Christopher James's book page 136 he says that a range of
1.8 is needed for Mike Ware's New Cyanotype formula. He say's "Mike
advises extending from base+fog (0.2) to a D-maz of 2.0 or more. This is
achieved by "overdeveloping" the negative to the extent of 70% to 80%".

Your development time is already beyond 100% but you only have a density
of 1.36. I would think this would tell me that there is something else
wrong. Its good to know how they are measuring their density range. I
didn't know if it was base+fog to D-max or shadow detail to highlight
detail. Looks like from this book its the former.

Now that I know this I wonder if your following zone system measurement
procedures and only reading shadows with detail and highlights with
details. If that's the case then you might have perfect negatives
already since it seems that alternative workers read everything not just
the details ;-)

-- 
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Chris Peregoy | http://www.gl.umbc.edu/~peregoy | http://imda.umbc.edu/