C-41 processing fault, need advice

[koraks]

what will happen if too much CD-4 is present, such as 10% or 20% more, in the developer?

You can expect an overall higher gamma and a bit of a color shift, although it may be unnoticeable in practice.

you keep on hearing people reuse the developer over and over without ill effects.

People say lots of things. Fact of the matter is that people who heavily reuse their color developer very rarely, if ever, post any meaningful comparisons between roll #1 and roll #...32? What illustrations are offered, usually are inverted and color balanced scans of roll #23 with a comment along the lines of "still going strong".

Let me tell you an anecdote. When I first got into color processing, I was being a cheapskate (still am, really, just more experienced at it) and I reused my single liter of Rollei Digibase C41 chemistry until the lack of density in my negatives was really undeniable. Well, I still got a couple of months of good use out of it. After all, dozens of films and sheets of 4x5 Portra scanned just fine - you know, within the normal bandwidth of the problems of scanning color negative film, and using some expired film as well.

Then I started printing optically and at some point I revisited some of the negatives I had developed...oh, I dunno, maybe halfway through that period I made the Rollei last. So I tried contact printing a particularly nice 4x5" negative that scanned perfectly well - only to find that its gamma in reality was about half of what's needed to make a decent optical print.

So how well did that single liter of developer really last? Did it last the many months & rolls + sheets I initially thought? Or only a fraction of it? Your guess is as good as mine. It depends entirely on what you expect and what you think you'll be doing with your negatives in the future. Especially the latter makes it a tough call, I think. Had I never started printing optically, I might today still have said "sure, go ahead and use your C41 developer for months on end and run 40 rolls through a liter, no problem at all!" And indeed, if someone only scans, and will only scan in the future too, and they're happy with what they get - maybe that really means that for them, personally you can indeed stretch the developer to remarkable lengths.

It seems it shouldn't matter if the CD-4 is gradually consumed in repeated reuse.

In reality, very little of the developer is actually consumed. This is not how the developer 'depletes', primarily. What happens mostly is (1) the pH of the developer shifts and becomes more acidic. This reduces its activity and affects color balance. (2) Halides from the film end up in the developer (this is a normal/expected side-effect of development), which also reduces its activity and again affects the image in numerous ways. If you reuse your developer, the results will shift with every development session. Even if you run 50 rolls through a liter of developer, I bet that the loss of CD4 due to actual development activity is minor - and the effect of this is insignificant in relation to the other two effects I mentioned earlier.

This also implies that you can't extend the developer's life by simply adding some CD4. You have to adjust pH, and you have to remove halides. The latter is chemically not possible/feasible, so the only way is to discard part of the developer and replace it with fresh developer. And this needs to be done before the halide levels reach such a height that the situation has become irreparable, too.

That seems too good to be true.

If it sounds that way, it usually is.

 

[lamerko]

This also implies that you can't extend the developer's life by simply adding some CD4. You have to adjust pH, and you have to remove halides. The latter is chemically not possible/feasible, so the only way is to discard part of the developer and replace it with fresh developer. And this needs to be done before the halide levels reach such a height that the situation has become irreparable, too.

Be careful when adding CD to the developer. The developer itself is strongly alkaline, while the CD is strongly acidic.
In the ECN-2 process, I once destroyed all chemistry. The solution without the developing agent had a pH greater than 11, while CD-3 itself had a pH of about 1.4. There was a healthy fizz and finally a brown foam came out with sediment on top. True, CD-4 is not that acidic, but C-41 is almost as alkaline...

 

[koraks]

There was a healthy fizz and finally a brown foam came out with sediment on top.

You can spritz some ethanol on the solution and get most of the 'sediment' (which really is an oil/greasy substance) to dissolve with vigorous stirring. It helps if you don't dunk the CD3 all at one on top of the developer as it tends to form globules that way that you can/have to break up in order to get the stuff to dissolve.

CD-3 itself had a pH of about 1.4

A dry substance has no pH.

 

[loccdor]

Expired Portra tends to hold up worse than other C-41s I have tried. I had the opportunity to try a bunch of expired films all stored in the same box for their lifetime. The Fuji films held up better, especially Pro 400H, which seemed almost new. NPS 160 does okay, though not great.

I think that if you want to form any conclusions on your processing, make sure to use some fresh film alongside the old stuff.

 

[pentaxuser]

I might today still have said "sure, go ahead and use your C41 developer for months on end and run 40 rolls through a liter, no problem at all!" And indeed, if someone only scans, and will only scan in the future too, and they're happy with what they get - maybe that really means that for them, personally you can indeed stretch the developer to remarkable lengths.

Seems like a pretty sound argument for scanning in terms of operating and darkroom set-up costs, especially if you have a scanner already


pentaxuser

 

[koraks]

Seems like a pretty sound argument for scanning in terms of operating and darkroom set-up costs, especially if you have a scanner already

Oh, and in a way, it is! It's just that I personally feel that the digital magic is not a substitute for, but a complement to analog magic.

 

[mtjade2007]

It's a huge extension in my opinion. It's capable of a lot more magic unthinkable to folks who have not put their toes to test the water.

Traditional wet printing pretty much requires the negative to be correctly (should I say precisely?) developed by the specs and the film needs to be well within expiration. Violating these requirements you either could have a hard time or be impossible to make a perfect analog print. The filtration filters of the color head of the enlarger have to be aimed mostly at perfect skin tones and have to leave remaining color crossover faults compromised. The choices of photo paper is fairly limited and so are the photographer's creative opportunities,

On the other hand, post processing to a scanned negative with a tool such as Photoshop undoubtedly opens up a huge possibilities of magic not possible by the analog way. Photoshop can correct a lot more color issues of a negative than color head filters can. It can adjust each individual color channel in highlight, middle tone and shadow individually. This alone makes it possible for an out of spec expired film to become usable and a lousily processed negative to be saved from a garbage can.

Photography is an art of creativity. A photo does not have to be printed exactly within a particular spec. It's all up to the photographer's artistic mind. A lot of times the digital magic may be controversial. But it's a subjective choice by everyone. It's more than a complement to the art of the analog way.

I am not saying analog magic is not creative. In my opinion allowing expired films to be usable and poorly processed negatives to be printable (to some degree of course) alone is enough incentive for a lot of people to go back to film photography again I believe.