C41 Developer Working Solution and Replenisher

[Josaw98]

Josaw98 submitted a new resource:

C41 Developer Working Solution and Replenisher - DIY

I have been producing my own C41 chemistry for a couple of years now and after developing over 1000 films I can share with you a stable formula and some useful tips.

The formulas are based on reading some Kodak and Fujifilm patents as well as my own empirical knowledge. You can see the result in the attached images.

Working solution:

Etidronic acid 1.5 ml

Potassium/sodium carbonate 25gr

Sodium bicarbonate 2.5gr

Sodium sulfite 0.8gr or sodium metabisulfite 0.5gr

Potassium bromide...

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[Rudeofus]

Interesting formula, and will most likely try this out at some point. There's one detail, though, which I would like to clarify: Dequest 2010 aka Etidronic Acid is a powerful sequestering agent for all kinds of evil trace metals, PE mentioned this one himself, but it comes with some problems of its own:
if mixed into alkaline environment, it seems to do quite poorly with regular water hardness. It was the first "good sequestering agent" I got my hands on, and I tried to use it to avoid the slight cloudiness of my HCA. It did get rid of the slight cloudiness, but within a few hours I had white fluffy pieces of something floating in my HCA. Something precipitated, and it may be an insoluble compound formed from Calcium and Etidronic Acid.

The one photographic recipe I have seen, which uses Etidronic Acid, used a combination of EDTA and Etidronic Acid. There is also a patent, which recommends lithium salts in developers, and I have indeed seen C-41 CD formulas with Etidronic Acid as sequestrant and large amounts of some lithium salt.