B&W processing temps (20 celsius) of C-41 using the normal C-41 results in utter disappointment imho. dMax - dMin is terrible usually and is very difficult to separate tones, making high grain + noise whatever your process plus crap colour. If you want useable (other than 'lomo') results from room temp processing, alternative processing is required.
30 celsius provides satisfactory results, in that you can get a colour image of good definition and fidelity (as opposed to 20c), but colour can be off by differing amounts from the highlight to shadow tonal scale instead of off by a consistent amount across that scale, and can be quite annoying to correct (highlights vs shadows may require different correction vs normal process which a single colour balance is excellent).
I have not had a single problem with C-41 @ proper temp @ 3m 15s on any film using the following method (never had streaking, etc):
Pre-Soak/Rinse (also gets tank+film up to temp) 40-42 celsius
Stop or Bleach or Blix
Normal from here.
Water stop/rinse after C-41 dev has caused problems for me after moving states and using a totally new water supply - in my case, high base fogging somehow. Until I started using stop or straight to bleach, then everything was dandy.
Yes the point I was trying to discover and PE and others seem to have confirmed this is that the high temp of 38C and quick development isn't simply "time is money" driven. It is inherent in the process and likewise it would seem that in B&W there is a limit to what can be successfully done at very high temps.
So the extrapolation of a line whereby dev time is shortened the higher the temp used, eventually breaks down no matter how much the "time is money" arch capitalists would prefer it not to :D
Two things: before C41 was invented, other processes were used and these could be run at room temperature. So no, you don't have to run all possible color processes at 38°C, but C41 was evidently designed for operation at this temperature and will not work well above or below 38°C. It's all how you design the process. Note that such a process consists of emulsion and developer, so there's not much we can do about this.
Originally Posted by pentaxuser
And second: b&w doesn't have the issue with color balance, so you could, in theory, run a b&w process way beyond 38°C. What will prevent you from actually doing this are the resulting extremely short dev times and in some cases considerable softening of the gelatin, but not the process itself.
It sounds as if you are saying that it is "time is money" driven. The C41 process consists of the type of emulsion and developer that has been arrived at and we the users are not in a position to use the "wrong" temp with the existing process but in your opinion Kodak and others could have devised another process that would work at say room temp There is no inherent reason why it has to be 38C. It isn't governed by any absolute laws of chemistry or physics in the way that at sea level the boiling point of water can only be 100C
Originally Posted by Rudeofus
Have I understood your reasoning correctly?
As far B&W is concerned the limits are much greater than we currently use. We could go to 38C and at these temps the emulsion wouldn't be seriously compromised any more than it is in colour neg development? Presumably if 3 mins 15 secs doesn't create short development problems for colour then it wouldn't for B&W?
Let me point out that C41 films contain DIR couplers. These are Development Inhibitor Releasers. They are designed to enhance color reproduction, sharpness and at the same time lower grain. The original process used was C-22 at 75 deg F. This worked to some extent in single layers, but did not in multilayers. Higher and higher temperatures were tried to no avail, and the image was just not right. Then two changes were made. They went from CD3 to CD4 and removed Benzyl Alcohol.
The rest is history. The 9 or so emulsions in 14 layers were designed to work with the DIR couplers and this turned out to be 3' 15" at 100F. It was not 3' or 4', as this just did not work out right.
At the same time, we were working with Ektaprint 3 and the new emulsions. We had to change the developer formula and then jack the temperature up to get 3' 30" for development time, even though our target was 3' at 85 deg F. The emulsions fought us every step of the way.
You see, chemistry does not do what humans want. They behave according to strict laws and the result is C41 at 100F and don't mess around with it. I can attest to this as one who has studied the results and was working in the same office complex as the film and process was developed. I then went on to coat the film myself!
If you process at any temp other than 100F, you stand a very good chance of getting quite substandard negatives.
Like it or not, but you just confirmed my "time is money" theory. Even if it would have been possible to create a process that needed 10 minutes at 20°C, nobody would have wanted it back then.
Originally Posted by Photo Engineer
PS: I fully acknowledge that Kodak would not compromise on quality in order to reach that speed goal. After all they still use separate bleach and fix.
There's a Fuji 2m 55s process time for one of their C-41 chemistry sets.
Yes, and they probably spent $1M developing it and used every film possible to test it, unlike what most do. It is probably also patented. So, a simple change in time and temp to an existing developer might not work, but a total redesign might.
The process for paper at that time was using 6' development at 85F. We found that by removing Cadmium and Mercury, the emulsions in single layers developed in less than 3' at the same temp, so we aimed for 3' at 86 as all processes were using that in the '60s. We also had to change a lot of other things.