Because of the demands of my commercial business, my B&W art printing time is rare and must be very productive. This week I was in the darkroom again printing a small portfolio for a museum and ran into some old demons. I have struggled for years to remove all the variables so that I can do a very consistent print edition of say 12 prints from the same negative in one sitting. Some of the variables I have worked with include: switching from a Zone VI stabilized head (with all the do dads which only help amrginally) to a voltage stabilized Beseler color head, temperature controling the room and the developer, replenishing the developer after each print, going to longer dve. times, 4-6 minutes, (there are other good reasons for this too), and carefully testing the safelight (threshhold test) so that I have at least twice the time I need to run a print. What am I missing here? I still occasionally get about a 5% variation (lighter or darker density in non dodged or burned areas) in the middle of a run out of nowhere. Is the problem in the timer? I use an old Beseler timer which when I test it is always consistent, but I swear in the middle of a run with long exposures (60 seconds plus) that it shorts me a few seconds. I'm ready to replace it. Any suggestions for a really accurate enlarging timer? What other variables might I be missing?