The use of a metronome when printing will yield much more precise results than using a timer, especially when dodging and burning-in.
The developer we use is a fast acting one--one you want with Azo. Developing for more than one minute is not recommended. With our formula, a one or two second difference in the devleping time will yield different results. That is very precise. And easy, really. I would not print like this if it were not easy.
Michael A. Smith