Newbie DIY C-41 Recipe/Formula/Process

[Adrian Bacon]

As part of my quest to DIY C-41, I've put together a shopping list that I intend to try out and thought I'd share it with the group for input before I pull the trigger and buy (would hate to buy the wrong thing). Since I'm a hybrid shooter, my goal is get something that will be scannable/digitizable more than printable via analog means.

A couple of things to note: I'm not a professional chemist, but I'm very technically inclined. I realize that I'm new at DIY C-41 and probably don't know what I don't know, so please just point me the right direction if I'm going the wrong way about something and heading for disaster. I'm not going to bite.

With that:

# C-41 Recipe/Formula (updated 2016-10-19, thanks RPC & sfaber17 for input!)

- C-41 Developer:
1. 700ml distilled water
2. 34.0g Potassium Carbonate (Artcraft Part #1250, $17.00)
3. 3.5g Sodium Sulfite (Artcraft Part #1416, $16.50)
4. 1.5g Potassium Bromide (Artcraft Part #1420, $12.25)
5. 2.0g Hydroxylamine Sulfate (Artcraft Part #1716, $16.00)
6. 2.0mg Potassium Iodide (note milligrams, not grams) (Artcraft Part #1290, $15.75)
7. 5.0g CD-4 (Artcraft Part #1095, $37.50)
8. Add distilled water to bring it to 1000ml.
9. Test ph, add Sodium Bicarbonate (baking soda) to bring ph down to 10.1, likely 1-3g. must experiment.

- C-41 Stop Bath:
1. 700ml distilled water
2. 10ml Glacial Acetic Acid (Artcraft Part #1689, $10.59)
3. Sodium Sulfite (Artcraft Part #1416, $16.50, purchased as part of developer above)
4. add distilled water to make 1000ml

- C-41 Bleach:
1. 700ml water
2. 80.0g Potassium Ferricyanide (Artcraft Part #1280, $18.00)
3. 20.0g Potassium Bromide (Artcraft Part #1420, $12.25, purchased as part of developer above)
4. Add water to make 1000ml

- C-41 Fixer:
1. 700ml water
2. 160ml Ammonium Thiosulfate, 60% (Artcraft Part #1050, $9.95)
3. 1.0g EDTA Disodium (Artcraft Part #1130, $16.00)
4. 11.0g Sodium Metabisulfite (Artcraft Part #1375, $6.25)
5. 2.5g Sodium Hydroxide (Artcraft Part #1759, $9.00)
6. Add water to make 1000ml.
7. Test ph, add Acetic Acid or Sodium Bicarbonate to get ph to 6.5

- C-41 Stabilizer: (per PE on APUG, definitive word on color stabs forum thread)
1. Photoflow 200 mixed per directions on bottle to make 1000ml.
2. 10 ml Formalin 37%

# Process (100F/38C)

1. 01:00 Pre-wet/temper
2. 03:15 Developer
3. 00:45 Stop Bath
4. 04:00 Rinse (8x 00:30)
5. 03:00 Bleach
6. 03:00 Rinse (6x 00:30)
7. 06:30 Fixer
8. 06:30 Wash (8x 00:30)
9. 01:00 Stabilizer

 

[RPC]

I think you can shorten the pre-wet to a minute or two.

If you are going to use a ferricyanide bleach then a clearing stop bath is advised. Add 10 grams/liter of sodium sulfite to your stop bath. The sulfite acts as a scavenger for developer. If any developer gets into the bleach it will be oxidized and stain the film.

I would increase the times of your "rinses" to 3-4 minutes or longer. One minute is likely not enough to remove the previous chemicals from the emulsion.

I personally have used a ferricyanide bleach of your formula, and use a time of 3 minutes, and for the fixer as well (I use regular Kodak C-41 fixer), at 100F. 2:30 just seems a little short. Kodak says 6:30 for the fixer, but says that works down to 75F, so I figure at 100F 3 minutes is effective but I may be wrong. Not knowing the strength of your fixer formula, it is hard to suggest a time.

 

[Adrian Bacon]

RPC - good info and thank you. I'm on my phone and will be out of office for most of today, so will modify/update this evening pacific time.

 

[sfaber17]

I think the fixer time of 2:30 is for the thiocyanate version of the fixer (C41RA). The one you have should be the 6:30 alright. It is nice to make everything from scratch, but in practice it might be cheaper to get F2 pack per RPC, and re-use the bleach by replenishing it and adding acetic acid to keep the pH at the 4.5 to 4.6 level. You then get some of the fast fixer as well in the pack.

 

[Adrian Bacon]

OK. Post updated. Thanks!

This does lead me to a few more questions: Reading other posts here, I gather that the ph is very important for the developer part, however, it appears (at least to me) to be more fuzzy for the other stages. How worried do I need to be about the ph for the other stages? Are they as sensitive as the developer stage or should I not worry about it? Most scratch/DIY recipes only seemed concerned with the ph of the develop stage.

Also, per guidance, I increased the process rinse/wash times to match the time of the step before it, meaning if I developed and stopped for 4:00, I rinse for 4:00 before bleaching. If I bleach for 3:00, I rinse for 3:00, etc. I imagine that rinsing for as long as it was exposed to the chemicals is probably enough, though may adjust upwards.

 

[Mr Bill]

I gather that the ph is very important for the developer part, however it appears (at least to me) to be more fuzzy for the other stages. How worried do I need to be about the ph for the other stages?

Hi, only the developer pH is critical - it affects the extent of development. The other chemicals are intended to do a "complete" job, meaning that there is no intermediate point - they either complete their job or they don't. Their pH needs to be in an acceptable range, but is not touchy as with the developer. You can normally get values for the acceptable pH ranges from the Kodak Z manual for C-41process, aka Flexicolor. However, the ferricyanide bleach is not standard, so I don't think it would be listed. (You might try the C-22 Z manual for ferricyanide bleach.)

If I were in your shoes, I'd want a way to know if my processing was close to the aims. The "activity" level of the process is only defined in terms of things called "process control strips," supplied by the manufacturers. The way this works is that they supply one already-processed strip, plus a package that you process (one at a time), then compare to the reference, preferably using a densitometer. The Z manual has a good section on process control, and how you might troubleshoot problems. Lacking this, you could have a test roll processed by a finisher that you trust, and compare to your processing. It just depends on how critical you want to be. Personally, if I were not gonna do some sort of evaluation of the final results, then I probably wouldn't even bother looking at solution pH values.

My experience includes years as the Quality Control manager of a large lab. My department included a full-time chemist or lab tech supporting our chem mixing operations among other things, so I have had pretty good familiarity with this sort of thing. As a note, if you print with an enlarger then the processing has to be pretty close to avoid what they call "color crosses," otherwise you may not be that worried about it. Best of luck with your attempts.

 

[sfaber17]

Your developer formula looks like the Zone V one from a recent thread with added iodide. I have tried similar formulas using the control strips but not quite that one. I'll try and run it when I get a chance and post the results. I would use a pH closer to 10.2 from my experience, but believe the formula will work pretty well.

 

[Adrian Bacon]

Thanks Mr. Bill. I'm a hybrid guy, so once it's processed, it's digital from there on out. I think it'd be cool to go all analog, however I don't have the space or facilities. My darkroom consists of a changing bag and a collection of Paterson daylight tanks and the downstairs bathroom across the hall from my man-cave. I have kids and a family, so the only place that's really mine to control is my man-cave, and even then, not really.

I'll invest in some process control strips just to see how close I am once I assemble everything. That will likely result in some minor tweaks to the formula, though I feel I'm probably pretty close with where it's at now, as I've looked at several of the recipes here and selected based on what I could readily get from one supplier.

Sfaber17, seen it referenced, haven't actually seen it, I guess I'll google it.

 

[Adrian Bacon]

Found the Zone V recipe. It's 32g of potassium carbonate and no potassium iodide.

 

[MattKing]

As a note, if you print with an enlarger then the processing has to be pretty close to avoid what they call "color crosses," otherwise you may not be that worried about it.

Even if you are using a "hybrid" approach you want to do your best to avoid colour crossover (parts of the image with one colour cast, while other parts have another colour cast). Otherwise you will be spending a lot more time post processing than you want.

 

[RPC]

Also, per guidance, I increased the process rinse/wash times to match the time of the step before it, meaning if I developed and stopped for 4:00, I rinse for 4:00 before bleaching. If I bleach for 3:00, I rinse for 3:00, etc. I imagine that rinsing for as long as it was exposed to the chemicals is probably enough, though may adjust upwards.

Here is my process at 100F:

developer 3:15
stop/clear 1:00
wash 2:00
ferricyanide bleach 3:00
wash 4:00
standard kodak c-41 fixer 3:00
wash 3:15
final rinse 1:30

I do not use a pre-wet. I start the developer temperature high enough so that during development it averages 100F with the processing tank in the water bath. But use a pre-wet if you wish.

I process in small stainless steel tanks and use the inversion technique. I invert the tank once every 10 seconds for the developer, every five seconds for the other solutions to help keep the processing times short.

The washes should use rapidly running water.

For process control I do not use control strips but simply shoot a gray scale on each roll and use it to check for crossover with my densitometer.

As was said earlier the ferricyanide bleach is not standard. PE has said that using it is taking the risk that it might affect the longevity of the dyes as this bleach has not been tested with C-41 dyes (it was used for the old C-22 process). But I know of people using it for years with no apparent problems. Due to the difficulty of sourcing standard bleach, I have decided to take the risk.

 

[Adrian Bacon]

I process in small stainless steel tanks and use the inversion technique. I invert the tank once every 10 seconds for the developer, every five seconds for the other solutions to help keep the processing times short

I use the Paterson tanks. I generally get better results with a tempered pre-wet with kit c-41, and won't do it any other way with black and white. Every time I've not pre wet with B&W it's turned out terrible (relatively speaking).

 

[sfaber17]

I have the test strip results from your developer formula. I did mistakenly use 35g of KCO3, but that shouldn't affect things much. I adjusted the pH to 10.23 using 5.40g sodium bicarbonate/liter.

Fuji strip Kodak strip​

Dmin 2,1,7 -9,-7,-2
LD -1,2(20) -3,-8,6
HD-LD -8,0,9 -5,-3,(-12)

The values are in hundredths of D difference from the control value. R,G,B.
HD-LD is high density minus low density, which is the contrast.
Parenthesis indicate the values that are beyond the control limits.

It isn't bad in summary. It is a bit low in activity. Maybe a higher pH would be better.
I use a ATL which times from the beginning of pouring and dumps 15 seconds before
the end, so it tends to be shorter than one would do manually, hence my values tend to be lower
than those. The formulas that beat this one out would be the C-27, C-29, my "N", and Phototechnologies (very close). The results should be quite usable, but ideally you would want more blue contrast on the Kodak.
Maybe the 2mg of Iodide is on the high side. I used the C41RA bleach and fix, so it doesn't reflect any possible variation due to your Ferricyanide bleach.

 

[EdSawyer]

Is there a reason you aren't just going with Kodak or other brand C41 chemistry? Not only be more accurate and less effort, but likely cheaper (based on those prices above). If you are doing it just for the sake of doing it DIY, I can see that (though I still find it a bit pointless, personally)

 

[sfaber17]

It

If you are doing it just for the sake of doing it DIY, I can see that ..

Yes, there is that, plus it is about half the cost of store bought. You also don't have to worry about it going bad before you use it. Arguably the bleach may not be that much cheaper given the reuse factor.

 

[Rudeofus]

Hi, only the developer pH is critical - it affects the extent of development. The other chemicals are intended to do a "complete" job, meaning that there is no intermediate point - they either complete their job or they don't. Their pH needs to be in an acceptable range, but is not touchy as with the developer.

AFAIK the pH of fixer is also important, since fixer is the last well buffered bath and its pH affects dye hue.

 

[Photo Engineer]

See the formulas I posted here for RA4. I'm working on C41, but there are several "official" Kodak formulas out there.

PE

 

[Mr Bill]

AFAIK the pH of fixer is also important, since fixer is the last well buffered bath and its pH affects dye hue.

Hi, I had thought (and said) that the pH specs were in the Z manuals, but it seems I was wrong - they are not! However one can still get these from Kodak's CIS-61 on the Kodak Alaris site:
http://imaging.kodakalaris.com/sites/prod/files/files/resources/cis-61.pdf

The developers are spec'd with a pH tolerance of plus or minus 0.05, whereas the fixer tolerance is plus or minus 0.25 for replenisher (the fixer TANK solution says typical is +/- 0.50). So the fixer spec tolerance is on the order of 5 or 10 times wider than that of developer.

We never studied dye hue shifts, but mostly worked with straight densitometer readings; we found that these correlated well to the effect on photo paper, which, as a production lab, was our main concern. Anyway, in my experience C-41 developer is pretty sensitive to slight pH variations, whereas fixer is not.

 

[EdSawyer]

I'd be surprised if it's cheaper than store-bought, esp. once you factor time into the equation. (presuming one values their time at > 0)

To me, the greatest cost is the time and effort to shoot whatever it is you shot, and risking the results of that with DIY C-41 chems is just not worth it (IMNSHO.)

Generally the unmixed C41 chemistry keeps well - easily over a year for unmixed Developer, for example. And nearly infinitely I think for bleach III. (and likely fix and rinse too, but those are so cheap as to not really be a big concern).

-Ed

It
Yes, there is that, plus it is about half the cost of store bought. You also don't have to worry about it going bad before you use it. Arguably the bleach may not be that much cheaper given the reuse factor.

 

[sfaber17]

I'd be surprised if it's cheaper than store-bought, esp. once you factor time into the equation. (presuming one values their time at > 0)

To me, the greatest cost is the time and effort to shoot whatever it is you shot, and risking the results of that with DIY C-41 chems is just not worth it (IMNSHO.)
-Ed

I tend to agree, I still use the factory chemicals for those reasons. Guess it is just a hobby. Maybe eventually I'll switch over to the homemade developer once it is proved out more.

 

[ZachHeaton]

I've been using your mix to develop my c41 work and I was curious how would you bring your PH level up. I for some reason am only getting 9.1 when I mix the dev.

 

[Adrian Bacon]

Are you adding any sodium bicarbonate in step 9? If so, don't. If you're not, to bring the PH up, you need to add something that has a PH higher than 10.1. Before all of that though, I'd verify that my PH meter is accurate and that I'm reading the PH correctly. Outside of that, there are a number of readily available over the counter high PH chemicals that are used for boosting the PH of BW developers that could probably be used in C-41 to bring the PH up as well. If you read through the thread, there's also a couple of variations that would likely result in a different ph reading.

All that being said, I haven't used this formula for quite some time as I have ready access to Kodak Flexicolor chemistry through my business, and I just put my own film into the processing queue and process it whenever I have an open spot in the queue.

 

[ZachHeaton]

Alright, I'll apologize right off the bat. I ended up redoing the calibration on my PH meter and the developer came out to 10.3. Guess that would of helped if I knocked that out before commenting. I will add in Step 9 and see what I can work out. Thanks again for posting this, you really sparked my creativity with film development. I tried out tyrodinal 72 hours ago and just tonight got to throw a roll of film in at 1:100. My chemicals for D76 scratch mix should be here tomorrow as well.

 

[Adrian Bacon]

Alright, I'll apologize right off the bat. I ended up redoing the calibration on my PH meter and the developer came out to 10.3. Guess that would of helped if I knocked that out before commenting. I will add in Step 9 and see what I can work out. Thanks again for posting this, you really sparked my creativity with film development. I tried out tyrodinal 72 hours ago and just tonight got to throw a roll of film in at 1:100. My chemicals for D76 scratch mix should be here tomorrow as well.

Great! As long as you’re having fun with it, that’s all that matters.

 

[Sajmonus00]

Hello. I want to start mixing my own c41 developer using this formula. How much films can i process in 1/2 litre developer? How long can I keep solution? (Stored in full bottle, no oxygen, no light) Thanks