C41 at room temperature

[dave_cheng1]

Ron, much water is really used in between steps to rinse the films.

But I agree it is always a good idea to conserve water. I like your

2 min. RA process. Sooner or later I am going to try it. It has been

more than 10 years since I last printed. In my frige I still have a

half box of paper that needs to be tossed out eventually. I believe

it's EP2 paper.

 

Seriously, I think it would be great if the C-41 formula is modified

to run at 70/75 degree for 5 minutes. I think that will cause a flood

of film shooters to buy films again. Well, this will have to be a

Kodak product so that people will not think it is a hack.

[rowland_mowrey]

Dave;

 

My RA process will NOT work with EP2 chemistry or paper!

 

It will only work with Endura RA papers.

 

By my estimate right now, the C41 process will require approximately 9 mins at 85 deg or about 20 mins at 75 deg. This is just from a nomographc based on data I have now. It certainly not accurate yet, as I have not done any experiments.

 

What I do, if it works at all, will not be a hack. If it does not work, I will say so and if it does work, I will submit print examples scanned in.

 

The problem is that due to diffusion rates, reaction rates, and agitation effects, the yellow layer starts developing first and the cyan develops last and more slowly. I'm in the process of addressing the balance between these to get a neutral scale that works. Scott's comments above notwithstanding, if you overagitate, overall contrast may not go up uniformly. Actually, the yellow may go up then magenta and finally cyan.

 

Ron Mowrey

[jordan_w.]

Guys, I have a Paterson C-41 kit at home that has the tables Anders mentions (time vs. temp). I will try to dig it up and post it when I can. They give info for processing C-41 down to (IIRC) about 29C. No idea about colour consistency at these temps because I just used it for XP2 super and cross-processing :)

[scott_eaton]

>>>>>>>>Firstly, a lower temperature process is more apt to give higher uniformity due to the longer development time.

 

Works for B/W sheet film, but less true for color materials. C-41 and E-6 films were designed for short process times from their inception. Big difference between tray developing Plus-X for 4-minutes which *IS* highly sensitive to minute changes in processing uniformity vs dye coupled Velvia in 4x5 which isn't. This isn't to say that color films aren't immune to processing uniformity issues, but in this respect you are creating a solution for a problem that doesn't exist. I've yet to see a uniformity problem with E-6 sheet film in a dip -n- dunk or Wing Lynch unless I have the nitrogen stream running right over the film. I can induce this problem more easily with classic B/W films, but again, color films are a fraction as sensitive as classic B/W films are.

 

>>>>>>You know that short development times are harder to control.

 

No arguement, especially when you are dealing with a hand prcessing system vs an electronic one under 5 minutes. Still, there's plenty of slop built into the C-41 processing loop, and even with hand processing E-6 I've never had a problem in terms of timing respect with even hand tank processing. What I do find to be a problem is keeping water and chems at 100F in an open jacket when the room is 70F ambient. That's a pain, and worth your pursuit.

 

>>>>>>The literature abounds with cautionary statements about getting agitation just right when you use short development times.

 

Ergo: For conventional B/W films. C-41 and E-6 films will react to changes in agitation, but not to the degree as classic B/W film will. I learned you really have to mess with drastic changes in Nitrogen burst times to cause 5-point changes in control strip tests.

 

>>>>>>>Secondly, agitation is less frequent at lower temperatures,

 

Which would tend to slant the over-all H-D curve to the lower contrast side, which is typically what most prints films, aside from maybe Max 400, don't need. Given my preference, I preferred to run our pro C-41 lines at 7-9 points over the Kodak spec because it just made the film look better, and customers agreed. Might be an issue with heavily replenished lines vs home C-41 kits, which will run hot anyways.

 

>>>>>>>>Thirdly, contrast or color shifts do not need to take place.

 

If you run E-6 film at a low temp and long process time you *will* get some form of crossover. I can guarantee it, especially with Fuji. C-41 being so much more tolerant of processing variables you might be able to fix it with basic linear adjustments like you said. Lower contrast it what I'm worried about with decreased agitation.

 

>>>>>>>Fourthly, all processes including bleach, fix, and stabilization are chemical processes, not mechanical, and therefore are affected by temperature.

 

Not true. Stabilizer and wash are primarily mechanical processes that work by simply permeating the emulsion in a mechanical form, which is why you usually just dump the film in stabilizer and let it sit for a couple of minutes. While formaldehyde in stabilizer is *supposed* to interact with organo-dyes in film, it's primary success is to simply saturate the emulsion and remain resident after drying. Formaldehyde based stabilizer also smells worse when it heated up, and will tend to pull the dyes out of the films if it's soaked too long. I've seen this first hand.

 

I've bantered about wash temps in the B/W forum for years, and insist final wash temp has no affect on efficiency.

 

 

>>>>>>>>If it does, then I can tell you how to process C41 films in off-the-shelf chemistry at any temperature and get good results.

 

I'd rather process film at a consistent temp in a simple water jacket at a reasonable temp to reduce variables. Given a home C-41/E-6 line, you're likely dealing with re-using chems, which also cause a color drift, so you now have two graphs to deal with.

 

 

>>>>>>>>>I'm sorry that you turn your nose up at the experiment before it is even completed.

 

I never disagreed about using lower temps since we know it works for RA-4, and actually improves the paper. I'm just uncomfortable about such a long process time becuase it causes problems on the other extreme.

 

 

[rowland_mowrey]

Stabilization of color films is a chemical process. The formaldehyde reacts directly with left over couplers in the film preventing formation of leuco dye, and buildup of stain. The correct chemical nomenclature is that the formaldehyde forms the methylene bis coupler derivative from the unused couplers. Sorry Scott.

 

As for color films, since they consist of roughly 3 active emulsion layers which must achieve the same contrast, it is a fact that the top layer will be sensitive to agitation more than the bottom layer, and that diffusion will play a greater part in overall reactions. When I refer to uniformity, I refer primarily to uniformity in single color patches for example, not to curve shape, nor to layerwise uniformity. OTOH, lower temperature allows diffusion across the width of and into the depth of a film to take place more smoothly than a higher temperature.

 

Acutally, I achieved optimum yellow curve shape at 18 minutes, and optimum cyan at 25 minutes at 75 deg for one example that I tested. No rollover or bad contrast, but a mismatch in time. I can antifog the Y and M back at 25 mins, or I can boost the cyan at 18 minutes. The problem is that I want to do this with stock developer, so it is a matter of other factors such as agitation and etc. For example, development of 25 mins with about 1 - 10 mg/l of benzotrazole would bring the Y and M into control, I would guess, but this would not be an off-the-shelf developer. Does anyone have an opinion about that?

 

The other solution is to use 18 min development to get the Y and M up to where I want them, and then use a 5 - 10 min rinse to allow the cyan to build up. That method has been used in the past on color films to bring the 3 layers into sync.

 

Any opinions on the latter?

 

Ron Mowrey

[dougmiles]

It's been some years since I've done C41 in my home darkroom, and then it was with Ilford's kit for XP1, and Unicolor's kit for color negs. Short dev time and high temps made it difficult. I would not mind adding a liquid additive to the developer, as that seems a pretty routine chemistry mixing type thing. Using a rinse as a change from the usual processing sequence is fine too, and seems an elegant solution, pardon the pun. If it works... wouldn't this also have less effect on the middle layer? (and agitation an issue). Same concern for the benzotriazole I suppose...? So the top two layers cannot be treated the same, while treating the lowest layer differently?

 

Doug

[rowland_mowrey]

Doug;

 

There are ways to treat each layer, during the development step. I can devise an antifoggant mix that deals with each layer in a different fashion. It has been done with color developers from day 1, but the formulas have never been published.

 

I just finished an 18 min dev, with a 7 min rinse, and it appears that it was still too 'hot' for the yellow and magenta, but too 'cool' for the cyan. The negative is still wet, so that is tentative until I read it.

 

If this turns out to be true, I may have to either go to 75 deg, or try the benzotriazole. You see, an antifoggant is selectively exhausted during diffusion into the coating. The yellow is restrained first, the magenta second and slightly less, and if I have the level right, the cyan will be unaffected. If you think this is impossible to control, remember that this has been used in actual products, so I know it works. The problem is finding the sweet spot.

 

Ron Mowrey

[silent1]

<i>For example, development of 25 mins with about 1 - 10 mg/l of benzotrazole would bring the Y and M into control, I would guess, but this would not be an off-the-shelf developer. Does anyone have an opinion about that?</i><p>

 

I wouldn't have a problem adding a single, easily measured chemical like a benzotriazole solution to a developer that I'm mixing from concentrate anyway, but I'd find it a lot easier to develop for 15-20 minutes at 75 F than to keep up agitation cycles for more than a half hour at 68 F, and still have twenty minutes of bleach, fix, stabilizer, and assorted rinse/wash steps to look forward to. In fact, in the summer my room temperature is often 75 or so anyway, and in the winter it wouldn't be any big deal to turn up the heat in the room I'm developing in.<p>

 

For that matter, from what I've been reading about C-41, I might just have to buy a liquid kit and try it at 100F (when I have money to buy chemicals, that is); apparently a lot of people do this with a plain water bath, and it works fine, nor do they have trouble with the short process time in the color dev. Of course, if I start developing C-41 negatives, then I'll have to find condensers and a filter set for my enlarger so I can try printing on RA-4 -- well, there goes the budget again...

[rowland_mowrey]

Donald;

 

Budget? Whats that?

 

Read my other post on C41 developers that I just made today. It came up during my research on this subject. I had it buried in some old books and remembered it.

 

I agree with you. Using 75 degrees or even 80 for 15 or 10 mins developement would be better than 68. I chose to start at 68 because my DR is at 68 all winter long and is pretty hot in the summer. Anyhow, the BTAZ probably won't work due to the fact that the activity crosses over with the magenta turning out to be the most active at 68 deg. That surprised me, as it wasn't in the past IIRC. It followed a more or less diffusion controlled activity order.

 

So, I'm moving on to 75 deg, probably tomorrow.

 

Ron Mowrey

[silent1]

<i>Budget? Whats that?</i><p>

 

That's what putatively keeps the rent paid and utilities on so I have a climate controlled darkroom, and electricity to operate the enlarger -- and hopefully still leaves money for film, paper, and chemicals. :)

[rowland_mowrey]

Guys;

 

I ran the 75 degree process, and 15 - 18 mins looks about in the ball park. The cyan is still a little low and the magenta is high IMO. That magenta has a lot of activity at lower temperatures.

 

I would guess that 15 mins with a 3 min rinse might fix up the entire problem, but it looks like there is no real way to get a perfect match. If close is good enough, then my Portra 160 VC looked fairly good at 15 mins.

 

Since EK tests RA paper across time and temperature, it appears as if the coupler activites are well balanced, but the film is apparently only tested at one temperature as a function of time. Therefore the reduced temperature paper process works, but at least from 68 - 70 deg, the film is way out of balance.

 

It may come back in at 85 degrees, and I may try this at some future time.

 

Sorry things didn't work out better, but it was fun trying, and at least I tried.

 

Ron Mowrey

[rowland_mowrey]

Final update;

 

I made proofs tonight to compare to my referece. These were all MacBeth color checker exposures.

 

It looks like 25' at 68 deg F and 15 min at 75 deg F give good color balance when compared to the check. They are a little darker in printing, so therefore lighter in density than the check, but not much. There is some crossover in the neutral scale from cyan in low density to red in high density areas (or just the reverse in the negative). It seems to be so slight that the color reproduction of the chart is quite good overall.

 

This result would indicate that the development time at 75F would probably give more acceptable results at about 18 mins or so. Since the old C22 developer time was 17 mins at 75F, this does not seem too far out.

 

I didn't play around adjusting the print exposures to make exact matches or anything. This was just a set of rough proofs.

 

Take it FWIW. It was fun and an interesting lesson in how they have changed color neg since I worked on it.

 

If I have time and energy enough, I may try 85 deg.

 

Ron Mowrey