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.