Dignan 2-bath color negative process, modification 1

Alan Johnson

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Already having most of the chemicals, I made this formula (A,B,C) and found it to work better at near 38C 102F rather than lower temperatures.
All the following solutions in containers are kept at around 38C in a sink or large bowl water bath. This water is also used for washing where indicated.
Waste water is poured into another bowl or bucket.
The solutions A,B,C are reusable and poured back into their containers after use.

(A) Developer- 5m ~38C , 2 inversions every 30 seconds. It just soaks into the film, no development at the low pH ~6.5 Keep in glass bottle preferably under inert gas.
Sodium bisulfite........................................1g
CD-4.............................................................11g
Sodium Sulfite anh..................................9g
Water to......................................................1L

(B) Alkali- 10m ~38C 2 inversions at start and then every 3 min only. It activates the developer that soaked into the film. This is the only step where a temperature close to 38C is significant.
Sodium carbonate anh 37g or monohydrate (USA) 45g or decahydrate (UK, +EU?) 101g
Potassium Bromide..................................1g
Water to........................................................1L........... Best to filter the resulting solution before use if washing soda. pH ~11.6

Wash 2x ~38C

(C) Bleach 5m 38C , 2 inversions every 30 seconds
Potassium Ferricyanide .........................40g
Potassium Bromide..................................25g
Water to........................................................1L

Wash 2x ~38C

(D) Fix [normal B/W fixer] 5m 38C

Wash 15m room temp, Photoflo, hang to dry.

References:

Dignan NCF-41 Divided Color Negative Developer

Claire Senft submitted a new resource: (there was a url link here which no longer exists) - Dignan NCF-41 Divided Color Negative Developer In the NOV/DEC 1995 issure of Darkroom and Creative Camera Techniques Patrick Dignan wrote an article on a divided color negative developer. Everything in...
www.photrio.com

C-41 color film development at home with two bath formula

After working a long time with B&W I decided to go Color. Some research on the Internet brought me to Henrique Sousa’s Caffenolcolor blog who experimented with C-41 at home and was very i…
oliopinto.wordpress.com

I am still at the stage of "wondering if they will come out". So far have used 10 yr expired film, Colorplus 200 and Portra 400, eg:

 
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afriman

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Very interesting. I'm just wondering what real advantages this has above standard one-bath developing, if you have to maintain a temperature of around 38 C anyway, which really isn't difficult for the short 3'15" it takes. Knowing you're following the standard process as closely as possible, provides a great deal of reassurance, as you know your results are bound to be within spec (or very close). Is there a substantial cost savings? The formula is very simple, so that may be an attraction - but only if it's going to be a lot more economical than standard chemistry. Does it yield special qualities or allow for control over results that isn't possible with standard C41? What is consistency like, assuming your goal is darkroom prints?
 
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Alan Johnson

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I would expect the results to be less good than proprietary C41 kits and processes and am not suggesting it as a competitor for these.
It appears to be better than the original Dignan formula, see eg the second reference, and the developer (A) pH ~6.5 may well be longer lasting than the developer from proprietary C-41 processes, pH ~10.
 

cmacd123

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wonder if that might work like some of the b&W two bath developers -where the method itself is limiting and the times are not a critical.
 

afriman

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cmacd123 said:
wonder if that might work like some of the b&W two bath developers -where the method itself is limiting and the times are not a critical.
Click to expand...
That makes sense, because the film can only absorb a certain quantity of the first bath (containing the developing agent), which is then activated in the second bath to do its work until it's exhausted. At least, that's how I understand it.
 
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Alan Johnson

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In the alkali bath B, CD4 developer reacts with exposed silver bromide grains in one of the color emulsion layers giving metallic silver and CD4 oxide. The CD4 oxide then reacts with a color coupler in that layer giving a color dye.
The bleach converts the metallic silver back to silver bromide which is then removed by the fixer leaving a color dye image.

Re the comments in the first reference, hydroxylamine sulfate is just a preservative vs aerial oxidation in proprietary developers, it is left out of the Dignan process in expectation that the low pH may serve that purpose.
I am not sure about the missing iodide, some may in any case be produced from silver iodide in the emulsion. Maybe someone can comment.
 

koraks

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Alan Johnson said:
monohydrate (USA) 45g or decahydrate (UK, +EU?) 101g
Click to expand...

The hydration/species depends on the source; I wouldn't say that they're restricted to regions. For instance, in local supermarkets (The Netherlands, so EU) I can get decahydrate as well as monohydrate. Either is also available, as well as anhydrous, through the more specialized chemistry channels.

Alan Johnson said:
hydroxylamine sulfate is just a preservative vs aerial oxidation in proprietary developers, it is left out of the Dignan process in expectation that the low pH may serve that purpose.
Click to expand...

I doubt that (rather strongly...); evidently the sulfite will protect the CD4 for a while, but my guess is that the CD4 solution as you formulated it won't be stable over the course of several weeks, let alone months. I did note your recommendation to store under inert gas, which will certainly help.
Of course, HAS would be one more thing to purchase, it's not always easy to get and like many things it's toxic, so I can certainly see the advantages in leaving it out.

Alan Johnson said:
I am not sure about the missing iodide, some may in any case be produced from silver iodide in the emulsion. Maybe someone can comment.
Click to expand...

I'm not sure either. In other, more traditional C41 developers, I have experimented with adding iodide or leaving it out. I never noted any difference. I did note that the developers I compounded myself gave slightly different (and less pleasing) negatives than those developed in Fuji developer. If someone's inclined to it, they might search through PE's posts on the topic; I think the iodide mainly plays a role in enhancing acutance, but don't take my word for it...

afriman said:
oes it yield special qualities or allow for control over results that isn't possible with standard C41?
Click to expand...

AFAIK the rationale behind this kind of developer was to try and compress the tonal range by means of local developer exhaustion. I doubt it works very well for that, but who knows?
On a related note; I did some testing a few years ago of pushing and pulling C41 film; both approaches worked quite effectively, but of course you have to account for it during exposure (especially pulling). While pushing can have a place to obtain much harder contrast from low-contrast scenes, the results I got from pulling were simply too soft to my liking to bother with it anymore. It might work for portraits. Anyway, that's of course not directly related to 2-bath C41.
 

halfaman

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Alan Johnson said:
hydroxylamine sulfate is just a preservative vs aerial oxidation in proprietary developers, it is left out of the Dignan process in expectation that the low pH may serve that purpose.
Click to expand...

Just for reference, CD4 concentrates of liquid commercial developers are totally acid (pH around 2-4). PE claimed that helps preservation. Compard Digibase CD4 concentrate (part C) uses sodium sulfite in a pH 2.8 enviroment according to msds file and it has an exceptional shelf life once opened. On the other hand, Tetenal Colortec CD4 concentrate (CD part 2) with no sodium sulfite declared and pH 4.3 is far worse.
 

Lachlan Young

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DIR & DIAR couplers are essentially actually doing what people (largely wrongly) assume two bath development should be doing - and the colour is supposed to end up in the right place only with normal development. Thus a two-bath C-41 is effectively a category error.
 
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Alan Johnson

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For clarity ,I believe when the concentrate is mixed , used once and then stored its pH will be about 10.
Shelf life estimates for this seem to vary, order of weeks maybe.

It's only an error if you are trying to duplicate the commercial processing solutions or kits. Colors from the Dignan process so far seem OK from the unmentionable process I have been using. Analog printing -I don't know.
 

halfaman

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Alan Johnson said:
For clarity ,I believe when the concentrate is mixed , used once and then stored its pH will be about 10.
Shelf life estimates for this seem to vary, order of weeks maybe.
Click to expand...

Target pH is 10, but I don't know what would happen to an unreplenished working solution. Tetenal gives 6 weeks for used developer solution in Colortec kit instructions but the development time varies a lot with reuse rate and activity depletion.
 

Lachlan Young

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Raghu Kuvempunagar said:
Any plans to test this two-bath C41 developer on XP2 Super?
Click to expand...

What do you assume this will achieve? Do you understand how DIR couplers react to increased exposure? The curve of XP2 Super used correctly in regular C-41 is a dictionary definition of exposure compensating behaviour. Dignan seems to have been quite ignorant of fundamental C-41 behaviour characteristics.

Alan Johnson said:
Colors from the Dignan process so far seem OK from the unmentionable process I have been using.
Click to expand...

It seems like a lot of effort for something less good than regular C-41 in terms of colour etc. If you could interfere with the DIR/ DIAR coupler reaction rates you could probably get somewhere in terms of altering densities relative to exposure, but potentially at significant sharpness cost - and all sorts of colour problems - I think people don't appreciate how much C-41 depends on emulsion design rather than developer/ development time fiddling.
 
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Alan Johnson

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"less good than regular C-41 in terms of colour etc"
I suppose this is correct insofar as the unmentionable machine I use is set to assume it is dealing with a standard C-41 processed negative and therefore outputs slightly wrong colours. But so far it has been no problem to correct these. Whether or not it is always possible is outside the allowable discussion of analog so I cannot reply to your comment.
 

Lachlan Young

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That's not really the point - the point is that functionally speaking the whole formulae is trying to ignore fundamental aspects of C-41 behaviour on the basis of effectively cross-applying assumptions about B&W & that will inherently screw up colour, no matter if a CCD/ CMOS and software are attempting to correct it to integrate to 18% grey.
 

Lachlan Young

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Raghu Kuvempunagar said:
Frankly, not much but certainly curious to know what it'll actually achieve.
Click to expand...

Very little that's useful. DIR couplers release more in areas of high exposure, effectively restricting density - so the problem is that you'd actually need to accelerate the reaction rate of the DIR coupler rather than slowing it (as 2-baths seek to do). In other words, the conception of Dignan's developer is backwards.
 
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Alan Johnson

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In the C-41 process the CD4 plus alkali has 3m 15s IIRC to diffuse into the emulsion and react, including with the coupler.
In the Dignan (modified) process the CD4 is already in the emulsion and only the alkali has to diffuse in, 10m was the unresearched selected time.
It's not surprising that these two processes should produce different colors.

Analog printing with filters is used to fine tune the C-41 process result, you seem to be claiming that it won't work with Dignan colors.
Even if this is true I submit that electronic processing, not to be discussed here, gives more options.
 

Murray Kelly

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Alan, I will watch with interest how you get on with Dignan's Double Dunk, as so many bloggers are enthusiastic initially then report back that the negatives are getting thinner and thinner.

I wonder if it is possible that iodide in the coating accumulates from roll to roll and degrades the effectiveness of bath #1.

Also I once asked my chemistry Professor friend what the HAS did and he said it was used as a "getter" of unwanted byproducts. How it knows which is good or bad he didn't say. The seller of my kit said it was prone to diminish the colour intensity, too.

Good luck with this one.
 

Lachlan Young

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Murray - and the rest of the participants in this thread may want to review Ron's comments to your's and other questions in this thread from 14 years ago.

I think the absence of the HAS is a major problem with this formula, but conceptually the whole formula completely misunderstands how DIR couplers work to modulate highlight density and sharpness in C-41. It's a non-solution in search of a problem that doesn't exist if the materials are used as designed!
 

Raghu Kuvempunagar

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Murray Kelly

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Thank you Lachlan, that was a trip back in time. I was a young feller then and I'm still asking the same questions. Gotta be me.

PE always spoke ex cathedra but there were other opiniins, too.

I did 2 films recently in the same tank and same film batch. One was blank and the other only just scanable. As ever, the mask was just fine. They were 2 x Fuji 200 110 films end to end, so no variation in depth of developer.

I am still seeking "the truth" !
 

koraks

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Lachlan Young said:
I think the absence of the HAS is a major problem with this formula
Click to expand...

It might be; could you venture a guess why it would?


Murray Kelly said:
Alan, I will watch with interest how you get on with Dignan's Double Dunk
Click to expand...

So do I; not so much with the intent of replicating or building on the outcomes, but just out of curiosity. I'm of the opinion that C41 film 'should' be processed according to spec - but there's nothing to stop the more adventurous from experimenting.
 
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