Hello, and I am new to this forum. However, I've been mixing C41 for as long as it has been around, and C-22 before that. In the 1980's, before easy Internet communication, there were publications by P. Dignan and others, and a newsletter that was put out by a fellow named Dale Neville. A lot of people shared information on the formulation of photochemistry for both B&W and color processing, but much of this information is lost to time.
If you scratch mix, you will pay under $5.00 for a 1-liter batch of C41 that will process at least 8-10 rolls of film and it will last a week or two with proper storage. Your investment in chemical stock and equipment will be in the $300-400 range if you purchase one to five pound quantities. Half the cost will be $150.00 or so for the CD-4 developing agent.
From these old newsletter sources, and from the photochemistry columns in Darkroom Techniques (now PhotoTechniques) magazine, and from lots of processing experiments developing shots of the MacBeth chart I learned that there are quite a few C41 variations that make color processing economical and relatively easy. The formulae I prefer use separate stop, bleach, and fixing baths. Once you complete the stop bath, the bleach and fix can be done in light, because developement is completed and the developing agents are neutralized.
I do not deviate from the 100F temperature, because C41 films are designed to produce optimal characteristic curves for the color emulsion layers at this temperature. There is no reason not to use the 100F temperature, because it is easily maintained in a dishpan water bath for hand processing. I place the solution bottles (1-liter) into the pan and fill it with hot (~140F) water, insert an accurate color thermometer into the developer bottle and in about 20 mins. the temperature rises to about 105F. Another shot of hot water for the bath stabilizes temperatures slightly above 100F, where I start the processing using Nikkor reels and tanks.
Here is the method I use to process C41 one or two rolls at a time in my darkroom sink--no Jobo, no autoprocessors, etc. I load my film in Nikkor reels, and I usually add a few frames cut from a roll of MacBeth chart exposures. In my opinion, the advertising that color is difficult to process and requires automatic equipment is false.
Once you stabilize your temperature bath at around 101F, pour 500 ml developer into the tank, douse the lights, drop in the loaded film reels, and put on the lid. If you start with solutions and bath at 101-102F, the temperature stays within a degree or so for at least 10 mins. While you develop the film, hold the tank in the water bath. Invert the tank twice every 30 sec and keep it in the bath for 3 mins. Then pour the developer back into the 1-liter bottle and pour in the stop bath.
Development stops completely and the rest of the processing isn't particularly temperature sensitive, because the bleach and fix steps both carry through to completion without significant effect on the color balance or the characteristic curves of the emulsion layers. Somewhere between 95-100F is fine for the remaining processing, and it's therefore only necessary to maintain the 100F temperature for the 3 mins processing in the developer, and the 15-30 sec that it takes to empty the tank and fill it with stop bath.
For bleaching it is hard to beat the old C-22 ferricyanide formula. It was changed to an Fe-EDTA formula owing to environmental consideration, and because the bleach and fix can be combined into a blix. Lately I really prefer the persulfate-quinone formulation that is clean working and long-lasting, and cheaper than blix.
After removing the lid, the stop bath can be poured out and the bleach/wash/fix steps carried out in the sink using a stainless steel stirring rod to agitate the reels. Use solutions from the water bath and don't worry about the temperature. Bleaching takes about 6 mins depending on the formula, and be sure to toss in a 1 min. wash before the fixer. Fixing takes about 6 mins to ensure that you have no remaining silver. The bleach and fixer, when used this way, last through two or three batches of developer. You know when you reach the lifetime of the bleach and fix by noting the increase in time for the solutions to operate.
After a final wash, and a dip in the stabilizer, your C41 processing is done. Any concerns about crossover or serious processing defects are revealed by processing some known-good MacBeth chart frames (taken on the same film type, of course). For that reason I generally favor bulk-loaded film from the same emulsion batch.
The formulary I use is available. It can be posted here, or I will be happy to e-mail a copy to anyone requiesting it, in M/S Word .doc format.