[quote="David A. Goldfarb"]Extending development time usually only increases contrast by increasing the highlight density without improving shadow detail.
With one exception. The use of very dilute developers in conjunction with minimal agitation procedures can result in a significant increase in shadow detail without increasing contrast in the highlights. On Michael and Paula's AZO forum there has been some recent discussion of the use of Pyrocat-HD with stand, semi-stand and minimal agitation procedures. I was intrigued by the reports and carried out some tests myself this week using what I call extreme minimal agitation. What I found was that this type of development results in a rather dramatic increase in effective film speed. For example, with rotary processing my normal EI for FP4+ when the negative is developed to a CI of 0.85 (for palladium printing) is about 125. With extreme minimal agitation procedures the EI increases to about 225, at the same CI.
Water bath development may provide an equivalent increase in EI, but I do not find that it gives any advantage over the use of a dilute developer and minimal agitation procedures.
Another interesting result from the use of extreme agitation procedures with dilute developers is that you get exaggerated adjacency effects and this can greatly enhance apparent sharpness.