C-41 stand developing

Processing C-41 by hand and getting consistency at the proper times and temps is not difficult. I (and many others) have been doing it for years, and I check my results with a densitometer for accuracy. In the past I got worse consistency from labs.

You simply cannot process C-41 at low temperatures for longer times and get quality results. For one thing you get crossover as discussed earlier and it would be difficult if not impossible to correct for this accurately with software as well as time consuming. In addition, the DIR and DIAR dye couplers used in the film and process simply do not operate properly at low temperatures to give proper color correction of dye impurities. That too, would be extremely difficult if not impossible to correct with software. That is why 100F is used instead of 75F which the old C-22 process used (before the newer dye couplers), and was what engineers wanted to use originally for C-41, but found the couplers worked best at higher temperatures.

I'm not saying don't do it, just be forewarned.