C41: Effect of pH on color balance?

I read on a post here a while back the assertion that in mixing homebrew C41 developer, if the pH is not at least 14 (or maybe it was 10 or something), the red layer will not develop properly. Can someone skilled in photo chemistry give me an idea of whether/how pH affects color balance in development?

I ask because I have a ton of a specific C41 film that is very useable, but scans of which show a pronounced red bias (ie on the positive scan). This is also reflected in darkroom printing -- using "typical" filtration, prints are too red. Presumably, therefore, the cyan dye layer of the negative is developing more fully than the other layers? I would like to experiment with the C41 developer formula to see if something could be altered to address this bias in this film stock. I asked about this a different way in previous posts, and was advised to shoot through a cyan filter, which is not the response I was hoping for.

The film is Kodak Hawkeye 400, which per its spec sheet is identical to Kodak Ultramax 400. It is really good film, and until Portra 400 came along, it was probably the finest grained 400 speed color negative film available.

I recently did a roll of Hawkeye in the Jobo and the color balance was normal, just like any other. This was with the Arista kit.

Yours may have been kept differently. Mine has a red bias, I have developed it in home brew and in commercially prepared C41 developer. I am interested to know if pH has an effect on color balance, as it is easily manipulable.

pH of C41 developer is 10.

I haven't used C41 for some time now, but when mixing my own chemistry I match the pH to be the same as Kodak C41. I must admit my home brew C41 comes out quite close to pH10 anyway, but nonetheless I alter the pH to 10.

With regard to your colour printing in a darkroom. If the filtration is different to what your standard is, then you just need to find out where it is different and adjust the filtration accordingly. Colour filtration changes from batch to batch of C41 films is a normal thing. More so, if the film has not been kept in the required conditions needed for storage; which I'm guessing hasn't been optimal.

Small changes from batch to batch is a normal occurrence, large changes can indicate storage conditions, processing conditions or exposure conditions as being possible problems.

The last thing I would be doing with a C41 process is to alter the pH to change an issue that can be corrected (presumably easily) in the darkroom.

Major colour changes that can occur with C41 film are those where one of the colour layers crosses over into another colour layer, if this happens then getting corrected colour prints is really hard to almost impossible.

Mick.

To reiterate: The purpose of my thread here is to understand if pH affects color balance, and if it would be a worthwhile experiment to see if changes in pH might reduce the red bias I have.Yes, I can shoot through a filter, and yes, I can correct on the enlarger, but that is not why I am here.

I've seen only very limited tests on developer pH, and it was a looong time ago - probably 20+ years. The commercial packaged developers took a slight pH shift - definitely beyond our statistical norms, hence the question, do we need to adjust it or not? We did some bench-scale tests, as is vs adjusted. My recollection is that the small pH difference was roughly the same as a small temperature or time difference. (You can get an idea roughly how these go by look at the Kodak Z manual for the process; go to the last part - the troubleshooting section with control strip graphs.)

Personally, I think you're off on a wild goose chase if you don't have a way to measure things. For example, I'm pretty sure you don't have a pH meter - you mentioned a pH of 14, which is probably about where "Drano" would be, way beyond C-41 developer.

If you're making home-brew C-41 developer, without specific known-quality components and no pH meter, etc., AND IF YOU WANT TO MATCH STANDARD PROCESS AIMS, here's my best suggestion, it's gonna be tedious. First, shoot a bunch of identical reference images, same roll of film. Hold them for a day or so to let the latent image stabilize. Have a commercial lab you trust process some for you - this is your ideal reference image so you'd like the lab to report the exact states of their control strips to you (you don't want to try to match an out of spec process).

The next step is to fine-tune YOUR procedure to match their results. So use what you think is a good commercial developer mix (best would be if your reference lab would give you a liter or two of their developer overflow - it's no good to them, but to you it's the exact developer mix that you need). So, develop some of your reference film in this developer, adjusting time or temperature until you can most closely match their processed negative. Once you can match theirs, you have a known mechanical situation for your personal process.

Finally, develop some of your reference film, under these same mechanical conditions - in your homebrew developer. Any difference from the lab-processed film is presumably due to your chemicals.

Now, you think the pH may be a culprit? Ok, pull off several samples of your homebrew, and make a series of pH adjuster additions - the actual pH will still be unknown, but you'll know exactly what you added to each one, so it will be possible to duplicate later. Then you develop some of your reference negatives in each developer sample. If you can match the commercial processing, well now you have an improved formula.

Best of luck. It's so much easier, though, if you have some control strips and a densitometer, and perhaps a good quality pH meter.

If you go to this Kodak process manual, you see on page 34 the effect of too much/little part A in color developer. How does this apply to your question? Color developer part A is mostly alkali and some sulfite, which means more part A gives higher pH. The decreased blue density with excessive part A probably comes from the extra sulfite (which competes with color couplers for oxidized developer and therefore reduces density).

I would therefore conclude, that alkalinity has strongest effect on red density and contrast.

Did you test the developer with other films? How old is your Hawkeye film? In another post you already mention it had a red cast.

twelvetone12 said:

Did you test the developer with other films? How old is your Hawkeye film? In another post you already mention it had a red cast.

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Yes, this is not a developer issue; I have used the same with many films, and the Hawkeye is the only one with the red bias.

Rudeofus said:

I would therefore conclude, that alkalinity has strongest effect on red density and contrast.

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Where the manual refers to red density, is that red in the negative, or red measured in a positive image? If the latter, it would seem that reducing pH might control my problem. If negative though, I guess a pH increase should be tried. And while I do genuinely appreciate Mr. Bill's comments and advocated rigor, I am happy with the system I have, except that this one film stock has a red bias. So I really just want to experiment with the formula just for this one film stock, rather than to seek to improve my overall performance, as for the most part, my negatives turn out satisfactorily.

newcan1 said:

Where the manual refers to red density, is that red in the negative, or red measured in a positive image? I

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The Z manual for the film process only deals with film, so it's talking about the negative.

I don't remember their exact terminology, but the plot drawn in red is actually measuring the density of the cyan dye in the negative. It does this by putting a red filter in the light path, so it's more properly called the "red filter density" or "cyan dye density."

I know you just want to experiment with things, but I doubt that you'll make any improvements over the standard "spec" condition - that's where everything is tuned to work properly. The three color layers all have matching contrast, etc. My suggestions are just a way to roughly get to that condition without using control strips, etc. If you do things to change that balance, typically the top layer gets affected first - "speed" and contrast, so you may get "color crosses" when you try to print.

Best of luck.

Mr Bill said:

The Z manual for the film process only deals with film, so it's talking about the negative.

I don't remember their exact terminology, but the plot drawn in red is actually measuring the density of the cyan dye in the negative. It does this by putting a red filter in the light path, so it's more properly called the "red filter density" or "cyan dye density."

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Thanks for this. So where it says that increased pH dramatically increases red density, it means the cyan dye becomes denser, which means red is increased in the positive print.That is very helpful. I realize it's a long shot, but I have tons off this stuff, so it does no harm to load a few short rolls and to mix a developer starting at say pH 9.5 and going up from there. You never know! Worst case, I fail, and just use a cyan filter on the camera.

Let me pose a counter question, what happens if you purposely change the pH of your developer, in essence customize your developer for a specific roll of film (or rolls) and then the next batch of film requires the standard developer mix? Far easier to adjust color filter packs or scan presets. And as I recall, even when working with fresh properly stored films the earlier stuff required far different filtration than the newer emulsions. Your work paradigm sets up a positive feedback loop, never a good thing, where your are chasing yourself to eliminate a variable. Better to standardize and use the standard soup and then fix it in the printing.

I would rather start with a good negative. This is not an endless loop. To put it in context, I probably have about 2,000ft of this film, so a specialized developer for it would not be so bad; it would likely be my "go to" film for quite a while if I could reduce or eliminate the bias.

@darkroommike: you can adjust color balance in filtration, but you can not compensate the speed loss from underdevelopment. Filtration also won't help if individual color layers have different contrast (aka color crossover).

The pH of any color developer affects final color balance!

PE

To be quite honest I don't bother checking the 'PH' or whatever, in fact I don't have the means to. I always mix a kit in one go and store the chemicals in glass bottles until I need them. I don't measure out each individual chemical, I just empty the lot into a mixing jug, rinse out the bottles and add that, then only very rarely do I get a colour shift when printing, then I alter that with slight filtration changes. (Some colour shifts can be an improvement as well.) Different light sources will give different results anyway, so why bother or worry about PH, I trust the manufacturers to get it right.?

Life is just to short to worry. I would rather be printing or taking pictures not worrying and wringing my hands about the chemical makeup.

You don't have to check pH if mixed from a kit, but you do if scratch mixing.

PE

I originally asked a specific question: "Can someone skilled in photo chemistry give me an idea of whether/how pH affects color balance in development?" It is somewhat endearing to know that some find life too short to worry, but I had a specific question, and I am grateful to those who answered it. I am neither worried nor wringing my hands, but rather energized by the fact that I might be able to produce better negatives from 2,000ft of film. Thanks to those who chimed in!

On the topic of pH, what is the best brand and source for cheap pH strips?

I googled and was overloaded with information. I stopped by the local drugstore and found pH strips marketed to diabetics for what seemed like 10x the cost of what I saw online.

WilmarcoImaging said:

On the topic of pH, what is the best brand and source for cheap pH strips?

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Meh, forget about them, they're anything but accurate. They're only ok to give you a quick ballpark measurement.

You can get an inexpensive pocket pH meter for around $80 or less.

PE

Thanks Anon.

PE, what brand/model do you recommend? Thanks.

I use HANNA meters.

PE

Thanks PE.