I have been able to keep my C-41 working solutions to last for more than a year, almost 2 years. I thought I should share this method with everyone here. I hope this will encourage more people to develop their own color films which will lead to more consumption of C-41 films and as a result it helps film manufacturers (Kodak and Fuji) to make more due to the long lasting consumption in the market. The benefit of being able to keep the C-41 chemicals for a very long time is mainly so that one can buy the chemicals in larger packages to achieve a much lower cost per unit of the chemicals without fearing that the chemicals will deteriorate and become unusable before they are used. I am sure a lot of experts in this forum know the fact that the only chemical in a C-41 process that will go bad fairly quickly due to oxidation is the part C of the color developer. Everything else (Part A, B of developer, Bleach,Fix and Final Rinse) mixed or in concentrate will last just about forever. They do last for years to me and they don't seem to go bad any time soon. A unopened developer Part C will last 1 - 2 years but once opened it will oxidize in 2 -3 months even unused and tightly capped in the bottle. A mixed working developer solution will last only 2 -3 weeks. This method is really a very simple one with a small extra cost. Just buy some CD-4 (Kodak color developer agent #4) in powder form available from Photographers Formulary. I do not know where else sells it so if anyone knows any other places please share them with us here. I have quite a few expired C-41RA developer replenisher packages, each contains 4 sets of Part A, B and C to make 10 liters of C-41RA developer replenisher with each set, 40 liters total. All my Part C bottles have gone bad and are unusable. I simply mix the Part A and B per the mixing instruction but leave the Part C out (discarded). This is an incomplete C-41RA developer replenisher and It will last for years even mixed. Before I use it I then mix this incomplete developer replenisher with C-41RA starter per the mixing instruction to make my incomplete C-41RA developer replenisher solution (still no Part C in it). I then add 5 grams of the CD-4 powder per liter of this incomplete developer solution to produce my C-41RA developer working solution. I only make one liter at a time so it will be completely used in a week or so. There is never any waste of it since it is completely used in a week. As a result I am not only able to develop C-41 films that yields beautiful negatives I have been able to reuse it (with some replenisher added to top up the lost portion due to rotary processing by my Jobo processor). I have been able to reuse it 3 - 4 times with no or very small lost of quality. The CD-4 powder when buying in bulk will cost about $1.50 per 5 grams. I am sure it can be cheaper still when buying larger bulk each time. The greatest benefit is I no longer worry about my developer going bad any more. I can buy any large bulk developer packages and never worry that I will not be able to use all of it before it goes bad. I will use the Part C until it eventually goes bad then switch to use CD-4 powder. Cost of the developer are way down, despite that I have to buy large packages each time but they will last for years before I have to buy again. The bleach is not very cheap but it will last forever unused even opened. I buy it in large containers (5 liter bottle) and never waste any of it. All other chemicals are fairly cheap and also long lasting. Well, there is one problem that I was once told. I also need to add something else in addition to the CD-4 powder. I have not seen any problems without it but I agree that there is another ingredient in the Part C that was discarded. Maybe because I am using C-41RA replenisher to begin with so it already has that missing ingredient in it. Perhaps I don't really need to add it. If so then I will just stick with developer replenisher always. Large developer packages are always sold in replenisher form any way. Just remember to buy some starter, which is cheap, too. Hope this is useful info for everyone. Any comments/suggestions are welcome. Thanks.