Concentrate and Working Solution for E-6 First Developer Based on Kodak's US5948604A

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Concentrate and Working Solution for E-6 First Developer Based on Kodak's US5948604A - E-6 first developer formula derived from patent US5948604A

Kodak provided a "teaching patent", i.e. a publication for preservation of knowledge, for their 5 liter E-6 home processing kit. The original patent text can be seen here. While anyone with access to these formulas and ingredients could start mixing and using, this article tries to make these formulas more accessible to amateurs. Please note, that all liquid ingredients except for dilute aqueous solutions and water are given in...

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Dear Rudeofus, I don't know if I can replace Potassium metabisulfite with Sodium metabisulfite, and if the dosage can be adjusted.

fert said:

Dear Rudeofus, I don't know if I can replace Potassium metabisulfite with Sodium metabisulfite, and if the dosage can be adjusted.

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Adjust by molar weight. Potassium Metabisulfite molar weight: 222.31 g·mol-1, Sodium Metabisulfite molar weight: 190.107 g·mol-1.

Hello,
has anyone tested the actual capacity of this formula under the patent? I know it's single use, but judging by the amounts of chemicals, it wouldn't be much different than the commercial kits currently being sold...

lamerko said:

Hello,
has anyone tested the actual capacity of this formula under the patent? I know it's single use, but judging by the amounts of chemicals, it wouldn't be much different than the commercial kits currently being sold...

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I have (re)used this to process 6 135-36 films in 2 film batches with 500ml. I used the times from the Tetenal E6 kit.

Thanks. I was really wondering about the capacity.

There will be no sudden breakdown of this chemistry. It just gets weaker and weaker until development times become excessive. While lower contrast can be compensated by raising dev times, on the way to that point of exhaustion colors will likely be all over the place. It's also a big difference, whether you develop 1 roll of 120 film in an inversion tank with 500ml soup, or whether you run 6 such rolls in a rotary tank with the same amount of dev.

That's where all these capacity limits break down: typical numbers are the result of lots of assumptions and averages, and for some reason even professional labs still need control strips. That's why many amateur kits are geared towards single use, and as soon as you reuse these chems you are basically on your own.

To what extent is the ion balance between sodium and potassium important?

Potassium ion in its hydrated form is a bit smaller than hydrated sodium ion, therefore the latter will diffuse more slowly. IDK whether this has a discernible effect on the outcome.

Thank you.
I was going through the resources with the formulas again and wondered whether it really matters.
Yesterday I rummaged through the fridge looking for something to eat, and from the bottom fell out the lost 16 mm Ektachrome roll that I'd bought two years ago for the Minolta 16 and generally for chemistry tests. Seeing it somehow rekindled my desire to experiment with the formulas again… Unfortunately, some things will have to be substituted. DTOD is definitely out, I'll torture it with thiocyanates. I don't have Dimezone-S either - it's not a problem to find a small amount, but the price is unpleasant. So it will be replaced with Phenidone (A/B). And of course HQMS-K - a key ingredient, but the price of around €30 for 70 grams makes home brewing pointless. I have a little, but I’ll use it as a reference. I’m just thinking about how to reduce some of the direct problems with substituting hydroquinone.
Separately, I have a large quantity of expired Ektachrome - 1000' of VN 5399, about ten 100' cans of 5005, 5017, 5012, 5018, and 5071 - all of it 35 mm, and I also have a huge amount of 70 mm Fujichrome CDU. Looking at Stefan's old thread, where he found a balance for his expired films… I think I'll play around a bit