They are not expensive, but most good C41 processing systems are designed to be used at a certain rate and may not give you expected results if you are using th

They are not expensive, but most good C41 processing systems are designed to be used at a certain rate and may not give you expected results if you are using them at home. With your standard non-chromogenic process, you often mix up a fresh batch of developer and then then throw the developer out after using it. This gives you nice, consistent results in a home lab. The chromogenic chemistry (C-41, E-6) is usually designed for high-volume, and that means much less waste, but it also means that the chemistry will be go of spec if you don’t process enough film. Basically, your chemicals are changing over time due to both natural aging processes (e.g. reacting with the oxygen in the air) and due to usage by processing film. If you don’t process enough film, the chemicals still react with air but aren’t being used to process much film. The same applies to RA-4 color paper. Even a small college lab is unlikely to print enough photographs to keep the RA-4 chemistry within spec. And unfortunately, out-of-spec color chemistry means color shifts, which are hard to correct in a wet lab. It’s not like B&W wet labs where you can easily fix problems with printing technique. There are alternative C-41 chemistry kits designed for home use. I don’t recommend them in general, because they are wasteful and very sensitive to temperature.