I was waiting for a dry spell to bring this up. A while back Judy made a statement that printing gum with little or no pigment allows for a very extended range. I looked back through the Post Factory issues and really could not find examples. Hey Judy thanks for sparking my interest.
Since I was messing around with the post-flash and was getting good results in extending tonal range of the print I decided to do some experimentation and actually print some test prints. http://picasaweb.google.com/marekmatusz1/ExtendedGumRange#
Two sets of tests are done with same water/gum/dichromate but different pigment concentrations. I have made different exposures and tested two development times. I used indantrone blue which is a wonderful dark blue and non-staining. I can not see that low pigment concentration extends the rane of gum print, to the contrary it allows less steps to be separated on a standard step tablet. One of the tests is also a good illustration of how delicate highlights with dark shadows can be printed with the same negative with the postflash.
Anybody else want to chime in. It would be great to see some illustrations. A picture is worth a thousand words.
This contrast vs. pigment issue has been on my mind for a while.