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Diy ECN-2 chemistry resulted in dark negatives?

Washing soda can be anything from anhydrous to decahydrate.

Mix up a test batch of developer with the right amount of carbonate and see how that goes.

filip0502 said:
I don't know how that affects the developer
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pH will end up way too high:

(quickly nicked from here)
Your developer should be at around 10.25 - 10.30 IIRC. Shifting the buffer to the right by adding an excess of carbonate will shift the pH point upwards. This will make the developer overactive and it will affect color balance as deeper layers (i.e. red, green) will develop faster in relation to the top layer (blue) than intended. It will also affect b+f, but the degree to which it happened here still makes me wonder whether this really explains what you're seeing. Still, it's definitely worth trying.

Also, if you can, test your developer with ECN2 film instead of C41, although the base of your C41 film processed properly in ECN2 should come out reasonably close in terms of density (not necessarily hue!) to the C41-processed sample you've got.
 
Ok, I think I got 69 grams because I googled that the washing soda I was gonna use was decahydrate, and then 69 grams would be correct. I ended up getting something different, and it's anhydrous.
How can I test the pH? Is that something people regularly do when mixing ECN-2? I remember in school, during chemistry, we used some papers that changed color based on the pH level of a liquid.
 
filip0502 said:
How can I test the pH?
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Strips or a pH meter. The latter are unreliable over the long term unless you get a really good one and maintain, calibrate & store it properly.
The papers you mention work, too, but are not very precise and really not exact enough for color photography unless you need to determine very gross deviations from target.

You can also just evaluate performance of the developer, but this requires everything more or less works OK. In your case, that's still an issue.
 
I mixed the developer again. Looks much better!
The top one is some old vision 3 500T that I developed with the new developer. Bottom is vision 3 250D I developed with the bad developer.
 
Oh, that looks a whole lot better! The top negative looks underexposed, but development looks reasonably close; perhaps a little thin.

So was this indeed the problem that @lamerko suggested, i.e. the carbonate mixup?
 
koraks said:
Oh, that looks a whole lot better! The top negative looks underexposed, but development looks reasonably close; perhaps a little thin.

So was this indeed the problem that @lamerko suggested, i.e. the carbonate mixup?
Click to expand...

Yes, it was the carbonate.
 
filip0502 said:
How can I test the pH? Is that something people regularly do when mixing ECN-2?
Click to expand...
In my experience mixing DIY ECN-2 the pH of the freshly mixed solution always comes out around 10.4 which I then adjust down to working strength 10.25 as @koraks mentioned. If you are mixing DIY I think having a reliable meter is absolutely necessary. A KCl glass probe will give you accurate readings and last quite a long time with proper care. I learned the hard way that the cheap ($70) meters will give you mostly accurate readings, but inevitably burn out in 2 months or less.
 
For some reason, I end up with a slightly lower pH. It's true that I skip Anti-Calcium and AF-2000. I don’t know the pH of AF-2000. But Anti-Calcium is a salt for which conflicting pH data are given, however, it appears to be quite alkaline, around pH 11. It makes sense that if it's omitted, a corresponding upward adjustment would be necessary.
Following @koraks idea, I prepare concentrates and, like him, I use sodium hydroxide. There's no way to get it exactly right, but a slight excess of hydroxide will simply require a small acidic correction, which is more convenient for me. The advantage of working with concentrates is that once I determine the correction needed, I write it down and afterwards just repeat it without having to measure and tweak each time.
 
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