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March 14, 2026

ECN-2 Color Developer Recipe

A quick guide to making your own ECN-2 color developer at home

ECN-2 film developer can be used to develop cinema film such as the Kodak Vision3 line or (now discontinued) Fujifilm Eterna. It can also be used to cross-process C-41 films. The ECN-2 process tends to result in a lower contrast image, which is ideal for color grading such as is commonplace in the cinematography industry that ECN-2 films are designed for. But C-41 films cross-processed in ECN-2 may be more “muted” than you would expect due to this nature.

TL;DR The Recipe

Note that these are listed in the ideal order of mixing, though it is not absolutely required to follow the order, but it is preferable. More on this later.

  1. ~850 mL of (preferably distilled) warm water (90-100°F)
  2. 2g Sodium Sulfite
  3. 1.4g Potassium Bromide
  4. 4g CD-3
  5. 25.6g Anhydrous Sodium Carbonate (30g if hydrated)
  6. 2.8g Sodium Bicarbonate (Baking soda)
  7. Water (preferably distilled) to make 1L total solution

Develop at 106°F for 3 minutes (180 seconds) for normal development.

Some Elaboration

Some of the ingredients will be quite difficult to dissolve, especially if the water is not quite warm, though try not to exceed 106°F. The developer will last about 3-4 weeks, especially if kept in an air tight container with most/all of the air squeezed out or otherwise removed. This is quite a bit shorter than C-41 chemistry shelf life! ECN-2 developer also in notorious for going from working great to completely dead instead of slowly degrading results as it dies. So it is not recommended to try using it on anything important after 4 weeks, probably even 3 weeks. Or if you must, then do a snip test to confirm it is not completely dead.

For convenience, I measure out the ingredients in batches and store them in brown glass containers until I am ready to mix. There is one caveat with this method though, I do not include the CD-3 in the pre-measured container. This is due to CD-3 being more volatile. Instead I will measure out the 4g of CD-3 per liter into the distilled water first then mix until dissolved, followed by slowly mixing in the rest of the pre-measured powders. The CD-3 is sensitive to the PH of the solution it is going into and I find that if it is not included at either the step listed above if measuring individually or first when doing pre-measured it will fizz aggressively and form some odd “chunks” which will never dissolve properly. This happens in commercially available kits as well, in particular the Film Photography Project’s ECN-2 kit will do this and they specifically mention it in their instructions as “floating particles” which is “normal” and causes no issues. But I personally don’t like them and will use a coffee filter to remove them if they do form.

When cross-processing C-41 film, there is a general common knowledge rule that you will lose 2/3 of a stop of effective film speed. This means that a 400 ISO C-41 film will actually show “correct” exposure if exposed at 250 ISO. So ideally you should either expose 2/3 of a stop over the box speed (i.e. either shooting at 2/3 of a stop slower ISO or setting exposure compensation to 2/3 of a stop over exposure), though most C-41 film will have enough latitude that this won’t make a massive difference. I like to compensate in development instead and develop for 3 minutes 15 seconds to 3 minutes 30 seconds or so for a small push to make sure the shadow details are as expected. Note that this is the same effect that can be seen the other way around. I.e. ECN-2 film developed in C-41 chemistry gains 2/3 of a stop of effective film speed. This is, allegedly, the reason CineStill films are rated at the ISO they are rated at. Kodak Vison3 250D film becomes CineStill 400D due to the change in recommended process to C-41, same with Kodak Vision3 500T → CineStill 800T.

Push and Pull Processing

The push times provided by Film Photography Project in their kit are wildly incorrect. Kodak has a page which lists the correct push and pull processing times. For quick reference, they are as follows:

  • Pull 1 stop = 2 minutes 30 seconds (150 seconds)
  • Push 1 stop = 3 minutes 40 seconds (220 seconds)
  • Push 2 stops = 4 minutes 40 seconds (280 seconds)

All times assume 106°F standard processing temperature.

Some Extra Notes

  • If unsure, your Sodium Carbonate is likely hydrated… it really likes to soak up water from the air, so unless it is new and/or well sealed with something like desiccant packets inside the container it will be hydrated or mostly hydrated
  • This recipe only covers ECN-2 developer. I use the aforementioned Film Photography Project’s ECN-2 kit to get bleach and fixer which will easily last 6+ months. In my experience it can last a year easily when stored with little to no air contact.
  • The mixture should be almost completely clear when initially mixed, but may go through some color changes during mixing. It will also become orange after the first roll is developed and darken over time as it both ages and develops further rolls. Color of the solution does not seem to be any indication of the effectiveness of the developer, however.

Further Reading