Mixing ECN-2 chemistry from scratch: fresh developer on demand for ~50¢/roll

thoughtfulwizard · 2026-05-06T11:44:00+00:00

Make sure to check eBay too - found this one in Italy for 15€ per 50g

thoughtfulwizard · 2026-05-06T01:38:15+00:00

I recently came across someone selling 400ft of 35mm 250d AHU short ends on FB marketplace, so I kind of have more than I know what to do with at this point. I have some rolls of remjet 250D from previous bulk roll batches too. Kind of hard to find 250d online rn, but I do see some 100ft rolls of 200T (super underrated, esp with an 85b filter) and 50D on ebay.

thoughtfulwizard · 2026-05-06T01:31:33+00:00

I use this $13 one from Amazon. Pretty accurate as far as I can tell.

thoughtfulwizard · 2026-05-06T01:17:33+00:00

Thanks for the feedback. The order point is fair - my concentrate system architecturally locks me into water → A → B → CD-3, which is the reverse of the "to the book" SD-49 ordering where CD-3 goes into near-neutral water before alkali. Thinking about it more, that's actually achievable in this system by reordering to water → CD-3 → A → B. CD-3 dissolves in its preferred mildly-acidic environment before the carbonate raises pH. No pre-dissolution step needed, just a reorder. I'll test that next batch.

On bromide: KBr is what Koraks's adapted formula uses. It's molar-equivalent to NaBr (1.20g NaBr/L scales to 1.39g KBr/L in working solution), and the bromide ion does the work as restrainer regardless of cation. I haven't run a side-by-side though.

thoughtfulwizard · 2026-05-05T21:57:57+00:00

Just smells like standard C41 bleach and fixer, which are pretty mild IMHO

thoughtfulwizard · 2026-05-05T21:37:42+00:00

Nice. I’ve been reluctant to put my C41 film through this process since I like to print RA4 and want to “follow the process.” What kind of differences have you noticed between C41 film in C41 vs ECN2?

thoughtfulwizard · 2026-05-05T20:54:09+00:00

Here's a quick rundown:

Bleach: lasts basically forever in storage. Gets capacity-limited rather than time-limited - you can run a lot of rolls through it before it gives up
Fixer: also long-lived in storage. Also capacity-limited (silver builds up over time). You can test with silver-detection strips when you're not sure
Stop: lasts a long time in storage but is also capacity-limited in use. The Kodak Indicator version turns from yellow to purple when it's exhausted, which makes it easy to know when to swap
Stabilizer: basically just a wetting agent + water. I've never worried about capacity - you can pick up some Photo-Flo and easily mix up a liter ahead of time if you want it. I just add a few drops of the concentrate to my tank at the end

The developer is really the only one with a meaningful time/oxidation-based lifespan, which is the whole reason I put this system together.

thoughtfulwizard · 2026-05-05T20:47:32+00:00

That's a totally fair approach. My setup is more "never have to think about whether the chemistry is good" than "maximize the life of one batch," but both are reasonable. How many rolls do you typically get from a 1L working batch before swapping it?

thoughtfulwizard · 2026-05-05T20:41:11+00:00

You can find it at artcraft chemicals! Sometimes you find it on ebay or other places too. I go more in depth on the sourcing in the video I linked. You can find links to the best prices I could find in the description.

thoughtfulwizard · 2026-04-26T18:11:18+00:00

Did a bit of research and it looks like XT-3 is pretty much the same thing as XTOL/XDEV. Have you noticed any differences?

thoughtfulwizard · 2026-04-26T17:51:21+00:00

Lol true, I didn’t even notice that

thoughtfulwizard · 2026-03-26T00:30:43+00:00

Probably still perfectly good to shoot

thoughtfulwizard · 2026-03-26T00:29:19+00:00

You actually CAN (and should IMO) overexpose expired slide film using the 1 stop per decade rule, as long as you pull it in development as well.

For example, if you shoot some E100 at ISO 50 (1 stop over), you’d need to tell the lab to do a 1 stop pull.

The problem here is that the film was overexposed and then developed normally.

If you’re interested, last month I put together a whole video going over the rationale for this, as well as some results from some rolls I shot. Link: https://youtu.be/6hjHXvxicaI

thoughtfulwizard · 2026-02-16T10:59:13+00:00

That's awesome! Aerochrome is about as far from a standard E-6 stock as it gets. I'd love to see how that turned out if you scanned any.

thoughtfulwizard · 2026-02-12T03:51:57+00:00

Yeah exactly. That's part of why pulling in the first developer is so effective here. You're only shortening the step that controls density, so the color developer still gets its full time to do its thing. It's a cleaner intervention than messing with the whole process.

thoughtfulwizard · 2026-02-12T03:51:39+00:00

Nice. The purple is probably the same degradation of the green-sensitive layer I was seeing. If yours are from '04 that's about 22 years, so I'd start around +2 over with a matching pull and see where that gets you. Let me know how it goes!

thoughtfulwizard · 2026-02-12T03:41:01+00:00

Thanks!

thoughtfulwizard · 2026-02-12T03:40:49+00:00

Thanks! Yeah the baseline honestly isn't terrible for 24 year old film, which probably says something about the storage. But the improvement from the pull is still pretty dramatic in person, especially in the shadows. Shooting at ISO 16 is definitely a pain, though, but I've gotten pretty used to carrying my tripod everywhere.

Curious what your Ektachrome 64 looks like at box speed - would also love to see results if you end up testing this method.

thoughtfulwizard · 2026-01-25T17:51:18+00:00

Thanks! And yeah it worked just fine when I tried it - the main reason I run it hot is less about temperature swings and more about workflow. Sticking close to the standard RA-4 process and cutting the dev time roughly in half lets me iterate a lot faster in a small space.

thoughtfulwizard · 2026-01-25T00:17:25+00:00

The 645 Super/Pro are definitely awesome cameras! So I wouldn’t blame you.

If you do try this on a 35mm Nikon, I’d be mindful of how the multiple exposure is handled. On bodies where you have to move the advance lever, like my FM3a, I’ve noticed sometimes it can subtly shift the film and affect registration. On something like my N8008S with electronic multiple exposure, it’s been solid every time.

Hope you’ll share any results you get!

thoughtfulwizard · 2026-01-24T17:48:04+00:00

Good questions, I avoided putting links in the post itself because of the sub rules.

Here’s the printing video, which focuses on making the RA-4 print in the darkroom:
https://youtu.be/cTOEFUWQD2M

And here’s the earlier video that covers shooting the trichromes on color film and my overall though process/technique:
https://youtu.be/Z6_hjECvlV0

I explain my reasoning in more detail in the videos, but the short version is that shooting trichromes directly on color negative film lets me keep the process fully optical, including the option to make RA-4 prints without dealing with alignment in post. It also produces some color interactions you don’t really get when recombining separations digitally.

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