A Color Monobath Developer Formula

[xiaruan]

I found a formula for a color monobath developer in a book, which claims to develop and fix color negative film in a single step at room temperature in just 2 minutes. I'm quite skeptical about this, but I currently don't have the means to test it. I'd like to hear everyone's thoughts on this formula.

Monobath Developer Formula

• Water: 750 mL
• CD-4: 4 g
• Anhydrous Sodium Sulfite: 10 g
• Anhydrous Sodium Sulfate: 60 g
• Potassium Bromide: 3 g
• Sodium Hydroxide: 52.5 g
• Sodium Thiosulfate: 25 g
• Add water to make a final volume of: 1000 mL

 

[koraks]

There's no way that the formula as stated will produce anything close to correct C41 development. However, I don't doubt that there will be some kind of color negative image and that it may be satisfactory for some users. Then again, even if that's the case, I struggle to see the advantage of this approach.

 

[thinkbrown]

Off the top of my head I don't see a bleaching agent so presumably it's gonna result in something like a bleach bypass?

 

[Samu]

No way. You will need a bleach in any color process. And you still would need to fix after bleaching, so adding fixer in color developer would be not a very good idea. You would get some kind of result though, nut it is hard to predict. I can guarantee though, it is not even close to the industry standards of a C-41 negative, nor do I know, is it even properly fixed.

 

[Josaw98]

CD-4: 4 g

The amount of CD4 in your formula is too low for it to be ready in the 2-minute development time you suggest, assuming you develop at 38°C. I have a Kodak patent for a developer formula that promises to develop your film in 1 minute at 48°C and uses a much higher amount of CD4. Remember that after color development, your film will contain three main components: metallic silver, silver halide, and azo dyes.

At the end of our process, we want to keep only the azo dyes and eliminate the metallic silver and silver halide that didn't develop in the developer. How do we do that? In the bleaching step, we convert the metallic silver back into silver halide so that the fixer can completely remove the silver present in the emulsion. Skipping the bleaching step will leave your emulsion with azo dyes and metallic silver, the latter of which will affect any printing/scan process you want to perform later.

 

[Raghu Kuvempunagar]

The amount of CD4 in your formula is too low for it to be ready in the 2-minute development time you suggest, assuming you develop at 38°C.

You might or might not be right, but notice that the developer is extremely alkaline (Sodium Hydroxide: 52.5 g) and that level of alkalinity would most likely make this developer very active.

 

[lamerko]

These 4 grams are not that small. It is not clear what the pH of this broth is. There is an absurd amount of hydroxide. However, there is also 10 grams of sulfite, which will block the formation of dyes to some extent. If this thing works somehow, as has already been said, the bleach is missing. When you think about it, there is no way to combine them.
The position of the sulfate is interesting - I suppose it is there, as a measure to protect the thiosulfate, but I do not know if this will work.
If the amount of sodium sulfite is enough to completely block the formation of dyes, this could be a formula for developing color film as black and white.

 

[xiaruan]

The book also includes a description of the principles behind this formula, but it seems there are some issues with it as well. However, since I'm not very familiar with color development, I can't pinpoint exactly where the errors lie.
The monobath development and fixation method proposed by the American 3M Company performs development and fixation simultaneously during color development. This process eliminates the bleaching step, leaves no silver residue, and produces satisfactory color images. The main components of the processing solution are color developing agents and fixing agents, and the solution is strongly alkaline (pH ≥ 13.2). Various types of color developing agents can be used in the monobath solution, but CD-3 or CD-4 are typically selected. The fixing agent usually chosen is sodium thiosulfate, but alternatives such as thiocyanate, mercaptosuccinic acid, and thioglycolic acid can also be used.

Excellent results can be achieved when using the monobath method to process various types of film.

The reason why the silver image does not affect the color image when using the monobath processing method is as follows: When silver halide is directly reduced and developed from its solid state, the resulting silver image has high covering power. However, when it is dissolved in the processing solution to form silver ions or silver complex ions, and then reduced and deposited on the latent image, the resulting silver image has low covering power. The monobath processing solution contains fixing agents that dissolve the silver halide particles. Even if the silver image increases proportionally with the dye image, the density of the silver image remains low, allowing light to pass through the silver image effectively. This ensures that the quality of the color image remains unaffected.

 

[lamerko]

I'm very skeptical about this formula, but there's nothing stopping me from trying it - it's simple enough. I might try it just to see what would happen, although I have very little CD-4 - I would change it to CD-3, of which I have a lot, but it's hard for me to estimate how much I would need, due to the different activity.

 

[Josaw98]

Puede que tengas razón o no, pero ten en cuenta que el revelador es extremadamente alcalino (hidróxido de sodio: 52,5 g) y ese nivel de alcalinidad probablemente haría que este revelador fuera muy activo.

It's good that you mentioned it; that's another serious problem. It's very alkaline, but I don't see a buffer anywhere. The color depends heavily on the pH, and such a high pH will almost certainly result in a dominant color, a huge color shift. All the formulas I've seen are always between pH 10.05 and 10.1. Just because it's so alkaline doesn't mean it will work. It will probably spoil quickly because the amount of sulfite is very low for that large amount of NaOH, and that raises another problem. On the one hand, a pH >13 will rapidly decompose the CD4, and that amount of sulfite will interact with the CD4, also reducing its effectiveness. It's recommended to use low amounts of sulfite (<1 g/L) when working with color developing agents, such as CD2, CD3, and CD4. That's why HAS or any hydroxylamine derivative is used in C41, as it works in conjunction with sulfite as a preservative. This monobath will probably decompose in 1 or 2 hours.

 

[pentaxuser]

xiaruan, who is the author of the book and from where was this formula obtained? Were there any pictures of the negatives that were made from this formula?

Thanks

pentaxuser

 

[koraks]

Even if the silver image increases proportionally with the dye image, the density of the silver image remains low, allowing light to pass through the silver image effectively. This ensures that the quality of the color image remains unaffected.

The notion that the image "remains unaffected" is, I think, a little (too) optimistic. This monobath can be expected to work as a bleach-bypass process with a significant color shift as well as crossover to boot. As I initially remarked, the results may be satisfactory to some. They will certainly not be excellent by any means. "Adequate", perhaps.

The concept is entertaining, but in my view lacks practical relevance apart from this novelty aspect.