I have long been under the impression that delta 100 and I suppose 400 is pretty stinkin hard to expand beyond N+1 (If you could even get it that far). Then I found this site and he says delta 100 can be pushed to N+2 in all kinds of developers at 68 degrees.
Arentz book says you can't get that high that you only increase density not contrast.
Does anyone know if this is possible?
I am thinking of Alt. process purpose negs.