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Saturday, March 29, 2014

Dignan's 2-bath developer

I have been using Dignan's 2-bath developer with some success. The pictures are quite different from a normal C-41 process, but nice. See, for instance, this one:

Dignan's 2-bath at room temperature

As is known, color photography works with 3 sensitive layers, each of them sensible to one the main colors Red, Green, Blue, from which a color image is done. Yhe red sensitive layer will give the color Cyan in the negative film, the green sensitive laer will give Magenta and the Blue sensitive will give yellow. Cyan, Magenta and Yellow are considered the inverted colors of Red, Green, Blue. So, the negative color image should have only diffrent amounts of Cyan, Magenta and Yellow and when positivated give a normal RGB positive image.

Dignan's 2-bath developer consists in soaking the fim in a solution of CD-4. the dye developer and then let it work in the second bath of Potassium or Sodium Carbonate.

My pictures, developed with this developer at room temperature present color shifts, what means that the dyes didn't get their CMY values. For instance the shift to Magenta instead of red means that the Cyan dye coupler became greenish. And so on.

What is the main difference between normal C41 process and Dignan's? The temperature! So, we must assume that the temperature will calibrate the CMY dyes in the film.

So I decided to use temperature in the second bath, around 40ºC. The results became more satisfactory, what colors shift are concerned. Look at this example, with no color correction via software:

Dignan's 2-bath using temperature


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