First of all, thanks a lot, stefan4u, for posting all this and going through all the effort researching this. Luckily we still get C41/E6/RA4 kits for small scale home users but I wonder when that will change. I would suggest that this ends up in some sticky thread where we collect all these formulations, especially the tested and proven ones. I recommend to all people who want to start experiment that they contact APUG member mts, he has a very fine collection of formulations for C41/E6/RA4, which should at least provide a starting point for optimizations.

Could someone more knowledgeable than me add the following info here?
  • Full official names of the chemical compounds listed, also possible ways of obtaining them.
  • Toxicity information about these chemicals, safe handling procedures. This has already been discussed here.
  • Possibly some info about longevity of the compounds and possible storage recommendations. I'm not sure whether CD4 has other uses beyond color film development and how easy it is to synthesize.


Remember that this kind of work is more important than all the dreading over film discontinuation. We (at least the hobbyists) can easily stock live time supplies of our favorite film stock in a freezer but all this won't help us if we suddenly lose access to dev process, ask the Kodachrome lovers here.

PS: Here is my minimal contribution:
  • CD4's official name is "4-(N-Ethyl-N-2-hydroxyethyl)-2-methylphenylenediamine sulfate", CAS number 25646-77-9
  • HAS is "Hydroxylamine sulfate", CAS number 10039-54-0