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Sunday, May 10, 2015

Variations on the 2.nd bath of Dignan NFC-41

Keeping the first bath like the original, I tried some variations of the 2.nd bath. I used four variations, from which I give the composition per Liter:

  1. 53g Potassium Carbonate + 1g Potassium Bromide - 30' at R.T.
  2. 53g Potassium Carbonate + 1g Potassium Bromide + 26g Sodium Sulfite + 0,4g Sodium Hydroxide - 30' at R.T.
  3. Parodinal 1:25 - 15 ' at R.T.
  4. Caffenol PC - 30' at R.T.
Without more comments, here are four captures of the same scene using the same first bath but different 2.nd baths:

!.st Variation
2.nd variation
3.rd variation variation
The first variation gives realistic colors but the 2.nd adds warmth, less grain and better definition. The 3.rd variation has high definition but almost no color but still some, may serve for artistic photos. The has no color, it seems that CD4 was completely blocked by the B&W developers. The last two variations were done in conjunction with incomplete bleach in order to keep silver in the emulsion but to clear the filter layers and give transparency.

Sunday, May 3, 2015

C-41, 2-bath developer and grain

I have been an enthusiast of the Dignan 2-bath developer for C-41 at room temperature. The 3 main advantages of this procedure, for me at least, are no need of higher temperature, no need to control the time exactly and it is a very cheap process. C-41 classic developing procedure was not thought for tinkerers but for professional laboratories with expensive developing equipment, I think.

However, many people succeed to produce excellent results following as close as possible the C-41 classic protocol. They already have experience on that, and they found themselves ways to control temperature and time with precision.

What disadvantages may I point to Dignan's 2-bath developer?

The first one is that you have to fight the color shift to magenta and low saturation. In my tests I came to the conclusion that you may reach better colors with a higher pH at the 2.nd bath. Dignan proposes a Potassium Carbonate bath at 5.3% with 0.5g/L of Potassium Bromide and Donald Quals suggest you may replace it with Sodium Carbonate, 4.3% of monohydrate, somehow easier to find. I prefered Potassium Carbonate like proposed by Dignan. On the other hand, Potassium Bromide require longer developing time, the suggested 6 minutes are not sufficient, you have to give much more. Because over-development will not occur, to be in the safe side I always let 30 minutes. And Potassium Bromide may be replaced with common table salt, 4g/liter.

For quite a long time I used Sodium Carbonate at the second bath and made color correction by digital post processing. But one day I tried to mix some drops of Sodium Hydroxide and I got very saturated colors without magenta shift. Then I discovered the original recipe and started using Potassium Carbonate.

The second disadvantage is the grain, I gave priority to the color shift but now that I am satisfied with the color, I started fighting grain. There is not much information about grain in C-41 process. No wonder because the development is standard, deviations to it are not allowed, if you get grain using classic C-41 developer kits, buy another one or change the film or the film speed. Many people report that over-exposure will lead to less grain, but with split developer I couldn't get any improvements.

Then I started thinking: why does grain form in C-41? The final image has no silver, so the grains are not due to silver grains but to dye spots. But the dyes form where silver was developed. If silver is developed without huge grains, dye spots will also be smaller, I thought. So, why not using Sulfite in the second bath as silver solvent, preventing silver grain/dye spots?

Yes! This supposition has been confirmed. I used following formula for the second bath:

5% Potassium Carbonate (50g/liter)
2% Sodium Sulfite (20g/liter)
0.4% Sodium Chloride (4g/liter)

Please enlarge picture to appreciate grain:

Developed without sulfite

Developed with sulfite

The film developed with sulfite has less grain but also a lower pH, thus the color shift to magenta is there again. Next step, make a small adjustment in pH to avoid color shift.