View Full Version : C-41 at Room Temperature

Donald Qualls
7-Jul-2007, 20:00
For the past couple months, I've been processing my own C-41 film at home (so far in 35 mm and 120, color 4x5 is pretty hard to manage on my budget, but give me time...). At first, I bought the Kodak Flexicolor "makes a gallon" sizes from Adorama, and was pretty happy with the results, though temperature control at 100F plus or minus half a degree was fairly annoying.

Once I used up the Kodak developer (which has about half the life of the other chemicals), I tried a formula I found on the Internet several years ago: Dignan NCF-41 (http://silent1.home.netcom.com/Photography/Dilutions%20and%20Times.html#2-bath_C-41), a 2-bath, room temperature C-41 developer, originally published a little over ten years ago.

I'm hooked; I'll never buy Kodak C-41 again. The original specification calls out 75 F for this developer, but since it's a two-bath, it's very tolerant. At higher temperatures, it won't overdevelop; it can't, because it develops until it exhausts the developer carried over in the emulsion from Bath A into Bath B. Below 75 F, I've found I need to give a little longer in the B Bath, to allow time for development to complete, but recently I've gotten good results at temperature as low as 70 F by adding 33% to the recommended Bath B time.

Best of all, this stuff is *cheap*. Even though the main component, CD-4, costs about $110 a pound, a liter of NCF-41 Bath A uses only 11 grams, so the 100 grams I paid $24 for will make about nine liters of working solution. And, as a two-bath developer, the Bath A lasts almost forever -- at this point, I've processed almost as much film in the first liter (replenished to maintain volume by adding more of the same working solution) than a gallon of Kodak Flexicolor Developer would manage, and its still going strong; even if I do as is commonly done with Diafine and discard the solution when I've used up an equal volume of replenisher, I'll get hundreds of rolls from the first two liters, and have three more batches the same size yet to be made up from the original 100 g of CD-4. The Bath B is mostly sodium carbonate, with just 1 gram of potassium bromide per liter, and though it's used one-shot, I use laundry grade sodium carbonate and get a hundred liters from a $3 box of washing soda.

The bleach (I'm still using Flexicolor Bleach II, though that will change soon) and fixer (also still using Flexicolor Fixer, again about to change) work fine at the lower temperature, though I've extended the times from what Kodak recommends -- since these processes are carried to completion, they can't be overdone, but I'm finding that ten minutes in each of bleach and fixer is sufficient even at 70 F.

Kodak's Final Rinse will probably continue in my darkroom -- it's hardly more expensive than PhotoFlo 200, cheap enough I doubt it's worth trying to replicate -- and unlike bleach and fixer, it's not chemically obvious what it does or how to tell if it's not working.

Bottom line, once I start mixing my own bleach and fixer for my color film, I'll be able to process a roll of 35 mm or 120, or four 4x5 sheets, for under fifty cents in chemicals including the amortized cost of the water filter I use to keep tap water junk off my film. At that price, I might just be able to afford to start shooting large format color...

8-Jul-2007, 03:32
If you buy the CD4 in larger amounts it's cheaper. I don't know what the current price is but I bought 1lb for less then $50 might have been close to $40.

Keeping the C-41 developer at the normal temp shouldn't be that hard. It's only 3'15".

I'd be suprised if you save much money making up your own fix and bleach. I've looked but the minilab jugs are so cheap for fix and bleach that it doesn't add up. Plus this stuff keeps.

To the important stuff how are the negatives printing?

Mick Fagan
9-Jul-2007, 05:03
Donald, looks and sounds quite good. I first did C41 using a Dignan formula from his book, "Simplified Colour Processing Formulas", which I started using in 1990.

I did try a two bath C41 at a lower temperature, but gave up as I was more interested at the time in absolute colour accuracy as I was doing a lot of colour printing. Having different colour packs for different processed films of the same batch, was quite difficult with colour filters in the filter drawer. I now run a colour head, so that wouldn't be a problem.

I concur with Nick, how are the negatives printing?

I note that you mention 11 gms a litre for CD4, is that amount a requirement because of the lower temperature? I ask as my version of C41 uses 4.8 gms of CD4 per litre, ( I do believe that 4.75 gms is correct but erring on the high side seems better).

Have you thought of re-halogenating the Bleach? I have been doing this for many years now and have found it to be cost effective. Bleach is the most expensive item in C41 by a long shot, anything to lower that cost has to be good.

You mention the Kodak final rinse, do you mean stabiliser bath with a wetting agent and Formalin?

My current costing for a 135 roll of film doing 4 rolls at a time for efficiency is $0.96 AUD a roll on a one shot C41 developer basis. The rest of the process, I re-use bleach (100 rolls) and fix (32 rolls) Stabiliser is one shot as well.

If you translate this to 4x5 sheet film, remembering different tank and solution sizes, it works out at $0.39 a sheet AUD. I know this as I have recently acquired some C41 4x5" film and did some homework on the developing costs.

As a comparison, B&W developing using D76 1+1 for 4x5" film, works out at $0.07 AUD a sheet. I purchased the chemicals in bulk in 1991, criminal isn't it?

In case you are wondering, I rotary process in a Jobo CPE2 with a lift.


Ron Marshall
9-Jul-2007, 09:04
Donald, do you use a mechanised processor, or are you doing it by hand?

11-Jul-2007, 12:52
Hello. I am from Moscow.
Sorry for my wrong english. Any way...
I do process C-41 at room temprature ( 24 degres by Cels) using my Jobo rotary drum processor CPP-2 with grait resalts many years.

1. Color dev. time .................................. 13 min. 30 sec.
2. Rince (or stop bath).............................. 30 sec.
3. Bleach ............................................... 6.0 min.
4. Fix .................................................... 6.0 min.
5. Final rince ...... according Illford recomendations - 5 times by 30 seconds on fast speed rotation.
If push needed, add 5 min to dev. time and you will have +1 step. Add 10 min for +2.

That is all. All approved many times. Good lack.

Donald Qualls
11-Jul-2007, 13:46
Hmmm. I replied to this once, I'm sure, but I don't see it now.

I don't print color (haven't the setup for it), but if I take the negatives to Costco or other lab to be printed, they'll get scanned and then output to the digital machinery anyway -- and these negatives scan beautifully, about 95% of them only requiring the automatic scan settings and auto levels before saving the unedited image; the remainder are affected more by either large areas of bright background or the color of the light (always an issue in the city).

I do aerate the bleach, but have only been using it a little beyond Kodak's recommended life of 32 rolls per gallon. And Kodak no longer sells Stabilizer; apparently both Kodak and Fuji changed their film around 5-10 years ago, and the films no longer require the formalin stabilizer. Instead, Kodak sells Flexicolor Final Rinse, which (based on the smell) contains no aldehydes at all (nor does it have a warning about them, as I'm sure would be required if they were present).

And I'm doing this by hand inversion in either stainless or Paterson tanks (I haven't yet shot color in 4x5, but shot seven rolls of 35 mm, processed at home, last week).

Mick Fagan
12-Jul-2007, 06:07
Donald, as I understand it, there is no longer formaldehyde in the final bath/rinse as the formaldehyde is inserted earlier on in the process.

As you are not using the type of process with the stabilising agents in the earlier baths, then perhaps it could be worth checking out whether you are able to easily make a stabiliser bath for your final solution prior to hanging the films.

The stabilisation of the colour dyes is, I believe, the reason for this part of the process originally being included. Speeding up the process and/or making things more environmentally friendly, is/was, probably another reason for moving the formaldehyde to another part of the process.


Donald Qualls
12-Jul-2007, 10:00
Mick, so far I haven't used non-Kodak chemicals other than the color developer. However, there's no warning for formalin or other aldehydes on the packaging for either the bleach or fixer in the Flexicolor "makes a gallon" packaging, either. What I understood to be the case, based on explanations from Rowland Mowry over in APUG, was that the actual chemistry of the film was changed, dye couplers (which determine what dye forms during development in a particular layer) altered to produce dyes that no longer need the aldehyde treatment to stabilize them.

There was a fairly major flap about aldehydes in photo chemistry, one which actually originated near your part of the world -- the place where the thing became public was a hospital in New Zealand, as I recall, where Kodak rapid-access (i.e. high temperature) x-ray chemistry was eventually implicated in a number of cases of previously unexplained whole-body sensitizations, not even due to contact, but simply due to inhaling vapor in poorly ventilated x-ray processing rooms over a period of time. After the usual period of denial and accusation, Kodak made a fairly big deal of eliminating aldehydes in all their processing products.

Now, in X-ray film, the aldehyde was there as a hardening agent, to keep the emulsion from lifting off the base when an X-ray film was processed at something like 120 F in order to complete development in two minutes dry to dry. It served a completely different purpose in color chemistry that required it.

I can report that there's no apparent change in my film from after the fixer to after the wash and final rinse; C-22 films at the post-fixing stage would have the dyes in what Mowry calls a "leuco" form, and they wouldn't even take on their final color until the formaldehyde reacted with the leuco dye to produce the final colored dye. C-41 has never had a leuco dye stage; a combination of different dye couplers and a different developing agent (CD-4 rather than the CD-2 of C-22) was responsible. Also, C-41 emulsion is pre-hardened at coating time to withstand 100F processing, so there's no need for an in-process hardener. Elimination of the stabilizer requirement was all that was left for Kodak and Fuji to eliminate aldehydes.

BTW, many/most third part chemistry kits still include a stabilizer containing formalin or other aldehyde, despite Kodak, Fuji, and even Ferrania having eliminated the need for it.

Similarly to eliminating aldehydes, Kodak Flexicolor bleach and others that copy it currently use a ferric EDTA derivative as the bleachant; this isn't because it's a better bleach than, say, ferricyanide with a halide source, but because the EDTA is more environmentally friendly for use in a large volume processing environment. Any bleach that converts the silver to a fixer-soluble form and doesn't damage the dyes formed in the color developer will work; ferricyanide is cheap, readily available, harmless to C-41 dyes, and actually less toxic than the EDTA bleach in the Flexicolor jug (as long as you don't mix it with stop bath); C-22 dye was ferricyanide based and the earliest version of C-41 dye might have been as well. An alternative, for those who prefer it, might be a long lasting iodine/potassium iodide bleach mixture, although that would greatly shorten fixer life due to iodide buildup in the fixer.

Mick Fagan
13-Jul-2007, 04:55
Donald, many thanks for the detailed reply. I'll do some further investigations. I have very little colour film left that is over 5 years old. The exception is some Agfa Optima of which I have quite a fair stash.

I've been using the same process for the last 16 years and have enough chemicals to mix C41 for about the next 15 years.


Darryl Baird
17-Aug-2007, 07:49
Where does one purchase CD-4?

17-Aug-2007, 09:27
Fotochem for one.


Ron Mowrey
17-Aug-2007, 09:52
A couple of comments are due here.

Leuco dyes are formed in C-22 and are converted to the final dye in the ferricyanide bleach bath. In C-41, the full colored dyes are formed in the development step. This alone makes the two films and processes basically incompatible.

C-22 and older C-41 films required formalin to stabilze the dyes and residual couplers from interacting and causing fade. Newer C-41 films don't need formalin but it can be used, as a secondary effect of formalin was as an antibacterial/fungicide for the film. The new final rinse helps prevent growth of bugs in the film during storage.

In the case of the hospital problem with aldehydes, it was due to glutaraldehyde in the X-Ray process which is apparently quite toxic in spite of the higher boiling point compared to formaldehyde.

Now to the final item... I've talked with Pat Dignan lo these many years ago when he was still with us. I advised him to stay away from CD-4 for processing color prints, and I advised him not to use 2 bath processes. He took the first piece of advice but not the second.

My reasoning for the advice on two bath C-41 developers is this. Color negative films are very thick, sometimes with 14 layers or more. And, between versions and manufacturers you will find that the number of layers, their position and their thickness varies. Along with this, the films contain DIR couplers to control the color reproduction and image structure.

The entire setup is based on control of diffusion through these layers and does not always work out the same when you change the developer or the development conditions. I have seen this happen. At best, the cyan layer on the bottom is under developed, or the yellow layer on top is over developed (or both). At worst, you have total crossover, fog, speed mismatches and etc.

Well, the final result is this. If you get it to work with film A under a given set of conditions, thats fine, but those condition will probably not work for film B and you will have to retune the development time(s) and temperature. In other words, with the Dignan developer (designed for a thicker C-41 film of over 10 years ago) you would have to test it with every film you use and get an optimum condition, and this is not a guarantee, just a guesstimate. Today's C41 films are drastically different than those of just 10 years ago.

Good luck.

Ron Mowrey

27-Mar-2008, 12:23
Anyone want to share how to manage and dispose of C41 chemistry in a home lab using well water and septic? The lab I'm using is nicking me $6 a neg for 4x10 because it takes up an 8x10 slot in their tank. I think I can save money since I am already wired for B/W processing using a Unicolor drum. Any recommendations for starting up this process?

Gary L. Quay
29-Mar-2008, 23:41
Where I live, household hazardous waste can be taken to a transfer station for free. They figure it's better to make it a free service than having folks pouring it down the drain. I save old developer, selenium toner, etc, in the bottles that I get my distilled water in, and take it there. I take my fixer to my camera store, and they take out the silver. I wouldn't dump the stuff down the drain, especially in a septic system, because it'll kill off microbes that make the septic system function, as well as potentially pollute the ground water.