C-41 with Kodak Flexicolor at Home


Developing color film at home is not as hard as some people make it out to be. If you have a safe place to do this and are used to working with photo chemistry, being able to do C-41 (and E-6) are well within your reach. This article will talk about how to do C-41 using Kodak’s Flexicolor kit!

When I first got started doing C-41 at home, I used the Film Photography Project C-41 kit .  After getting comfortable with this kit, I started reading about C-41 online and found out that Blix (very common in the kits) isn’t really the best stuff to use in the C-41 process. Blix was really designed for RA-4 and when you use it in C-41, it causes your images to lose shadow detail and highlights. As I shoot film with the intention of getting the most out of it, this bothered me.

I began immediately to work on figuring out how to get a separate bleach and fixer so as to eliminate Blix from my process. I found that I could use Kodak Flexicolor bleach and fixer with the developer from the Film Photography Project kit. This proved to not be terribly sustainable as I found myself paying $20.99 for C-41 Developer that according to the instructions is only good for up to 8 rolls of 135mm at 36 exposures. Further, not using the blix meant that I was stockpiling blix chemistry packets.

In my reading on separate bleach and fixer, I had come across methodologies to use entirely Kodak Flexicolor chemistry, but the thing that held me back was you had to mix 5L of the developer at a time. That’s a lot of chemistry to mix and keep. The FPP kit claims that you can’t trust the kit chemistry after 7 days and so I got hung up on the idea that storing 5L of C-41 developer for any length of time would not be wise. Over the past two years, I’ve learned a lot and now understand that Flexicolor developer is never stored at a working strength and that allows you to store it for longer.

After much research on-line, guidance from the people at the Film Photography Project on developing C-41, and my own trial and error, I am bringing you my guide to C-41 with Flexicolor at home.

DISCLAIMER: I cannot be held responsible for anything that you do as a result of following any information in or linked from this post. This post is about conducting a chemical process which could cause harm to you and others if not conducted appropriately. Please read all safety and MSDS specification sheets for any chemicals that you purchase for this and other chemical processes that you may decide to undertake.

Why bother with Kodak Flexicolor instead of the kit?

  • Kodak Flexicolor chemicals are considered to be the best you can get. The developer is less contrasty than the kit developers, giving you more detail to work with.
  • Separate Bleach/Fix process does result in more shadow detail, more highlight detail, and sharper negatives compared to using a Blix.
  • Kodak says you can keep developer replenisher for 6 weeks. People on the internet have claimed keeping it longer than a year with no degradation in quality. If you are really concerned about quality on older chemistry, you can buy control strips, develop them in your chemistry and use a densitometer on the control strip to determine how good your chemistry is. That said, C-41 developer doesn’t just go like XTol. It deteriorates over time, so you’re not going to lose your pictures. The results may simply be less than optimal. I’ll update over time as I have my own experience to add going forward with this process.
  • Your cost of development (after the initial outlay) goes down.

Why use the kit instead of Flexicolor?

  • The kit is much more convenient. Just three baths and one wash and you’re done.
  • The kit developer is more contrasty if you like that sort of thing.
  • You’ll be supporting the fine folks at the Film Photography Project!

Things to Purchase

As you will not be using a kit, you have to purchase a number of different things.  Let’s go shopping:

If you already develop black and white film, you’ll have a decent bit of this stuff already. That said, it is a lot of stuff, so you’ll need some place to store it all. Also, you can get by with less than what’s above, but my instructions will use every bit of the above.

Chemistry Preparations

Prior to developing film with this process, you will need to mix some chemistry.

For the C-41 developer, you are to mix it right before you need it and use it only one time. That said, you have to mix developer replenisher, developer starter, and distilled water. Developer starter is a separate chemical that you can purchase from the link above. This chemical has no problems with oxidation and does not really expire. It has an expiration date on the bottle, but can be used well past that date. I started this thread on photrio.com if you want to read more on this subject: https://www.photrio.com/forum/threads/kodak-flexicolor-delevoper-starter-lorr-expiry.167770/#post-2182490

The developer replenisher comes in 3 bottles – Part A, Part B, and Part C. To mix developer replenisher, you will need to put 4L of distilled water in the 5L graduate and then add all of Part A to the graduate. You then mix this with a chemical stirrer for a few minutes.

Developer Replenisher Supplies
4L of Water and Parts A, B, and C Ready To Go

Once this is done, you add Part B to the graduate and mix with the chemical stirrer for a few minutes. Then, you add Part C to the graduate and mix with the chemical stirrer for a few minutes. Once this is done, you fill up the 5L graduate with enough distilled water to actually hit the 5L mark. Mix with the chemical stirrer again and now you have a very full and heavy 5L graduate with developer replenisher. I carefully use two hands (one on the pour spout itself and the other on the handle) and pour the first 1L into a 1L graduate, measuring it out exactly. Then, I put the funnel in one of the 1L glass bottles and pour the 1L graduate into the glass bottle and cap it off. Then repeat that process for the remaining 4 glass bottles. You have now made developer replenisher and while Kodak says this lasts 6 weeks, I have personally used it 4 months later. Given that 5L of developer replenisher is enough for 6 1L tanks of C-41, this stuff doesn’t usually sit unused for long.

With the 5L of C-41 bleach that is recommended in this guide, you simply measure out 1L of C-41 bleach into the 1L graduate and then pour these contents into the 1L glass bottle. You do not have to worry about oxidation of the other 4L as bleach needs to be oxidized from time to time. C-41 bleach lasts a long time and I can personally get 1-1.5 years of C-41 processing off of a tank of bleach. When it stops needing to be burped and gets really to be more brown than green, you’ve exhausted your bleach and should dispose of it properly and mix new.

With regards to C-41 fixer, you use this in a 1+1 dilution, so you would mix 500mL of fixer with 500mL of distilled water and then pour this into the 1L glass bottle. Note that I have not used the linked fixer, so do not know how that one arrives or how much you really have. If somebody has purchased this fixer and would like to help me write this section, it would be most appreciated. I am using fixer from the now discontinued F2 kit.

Regarding final rinse, this is mixed by adding 991mL of distilled water to the 1L graduate and then using the 1mL dropper to add 9mL of final rinse to the 1L graduate. Once this has been done, pour these contents into a 1L bottle. Final rinse goes a long ways. Take a note of its starting color and when it starts getting murky and darker, it’s time to dispose of it and mix new final rinse.

Getting Set Up

Ready to Mix Developer

The first thing that I do when developing with this method is to mix working developer. The formula for mixing 1L working developer is 763mL Developer Replenisher + 30mL Developer Starter + 207mL Distilled Water. I put the 763mL of developer replenisher in my 1L graduate and the 30 mL of Developer Starter in my 150mL graduate. I then pour the developer starter into the 1L graduate and use distilled water to get the liquid line up to 1L. I then pour this into a 950mL glass bottle (they really hold 1L). Take the remaining 237mL of Developer Replenisher and put it in a 250mL glass bottle. If all of your 250mL glass bottles are filled up, discard the remaining developer replenisher. As you collect leftover developer replenisher, you will reclaim enough for 6L of working developer off of the 5L solution.

Since you need to keep the temperature of your Flexicolor developer to 100F with a +/-0.25F range, you really need a water bath. There are many ways to accomplish this, but I have chosen to use a bucket and a sous vide. Links to both of these are above. With the items that I have, my sous vide has a maximum heating capacity of 15L, or 3.96G, so I need to ensure that my bucket doesn’t contain more than 15L of water in it. That said, you also have to ensure the water line crosses the minimum fill line on the sous vide with nothing in the bath. If this causes you to go slightly over 15L, that’s fine.

Once I’ve filled the bucket with water, I attach the sous vide to the side of the bucket and turn it on to 100.4. This falls out of the range for your developer, but you will have temperature variations as you take the tank out of the water and put it back into the water, so you want your water bath to be slightly warmer than your desired developer temperature.

After turning on the sous vide, I put the glass bottles containing my working developer, bleach, and fixer (at 1+1 dilution) into the bucket and also put my tank loaded with film into the bucket. Currently I’m using a heavy pot to weigh my tank down (it floats otherwise) — this part is necessary and rather difficult. You must have the temperature of the tank at the temperature of the water or you will lose a significant amount of temperature on pouring the developer in and you really do only have a +/-0.25F range on this chemistry.

I have found that my sous vide device is significantly accurate temperature wise above 105F, but below that, it does not agree with my Paterson Color Thermometer, which I trust wholly. As such, I had to use the calibration on my sous vide to ensure that the temperature it reads matches the temperature of my thermometer. Once I got the sous vide calibrated to my Paterson thermometer, everything works fine and I certainly wouldn’t use this sous vide for anything else, so it just stays set these days.

After you have the thermometer and the sous vide calibrated and the chemistry and your tank in the bath, it’s time to wait for everything to come to temperature. I use my Paterson Color Thermometer to determine when the developer is at 100F.

This is a good time to make sure your chemistry disposal jug is readily available for dumping the developer.

Warming Everything Up to Begin Development


Once your developer is at 100F, you are ready to begin developing. Carefully remove the heavy pot, take the lid off your tank, and pour the developer into the tank, capping the tank. Start your 3 minute and 15 second timer (I’m using the Massive Dev Chart timer.) Agitate by inversion for 30 seconds and place the tank back in the bucket. This is a good time to put your funnel in your chemistry disposal jug. After this, every 15 seconds you need to agitate for 2 seconds (which for me is one agitation cycle). When you timer has 10 seconds left on it, go ahead and start pouring the chemistry in the tank into the disposal jug. This should finish right as the timer is going off.


Whew. Now the film is developed and the rest of these steps can be carried out in a temperature range of 75-105F. What a far cry from the 0.25F tolerance of the developer!

Now pour the bleach into your tank, set a timer for 6 minutes and 30 seconds and do an initial agitation by inversion for 30 seconds. If your bleach is good and active, you WILL need to burp your bleach. This simply means when you have finished the agitation, simply release the air in the tank and re-seal the lid. You’ll probably have to burp the bleach with every agitation. If your bleach does not need burping, then you need to aerate the bleach. Now is also a good time to clean the funnel and put it in the empty bleach container. Once you have finished this initial agitation, you will need to agitate for 5 seconds every 30 seconds. This is a different agitation pattern than for developer, so pay careful attention to that. Use the last 10 seconds of this step to drain the bleach back into the bleach bottle.


Set a 1 minute and 30 second timer and if you have soft enough water, use running tap water direct to your tank. The flow of water should be fast enough as to fill the tank every 4 seconds. If this does not describe your scenario, please see the document on running Kodak Flexicolor in a small tank linked below for an alternate wash method. At the end of this wash, drain your tank.


Pour the fixer into your tank and set a timer for 6 minutes and 30 seconds and do an initial agitation by inversion for 30 seconds. Clean the funnel and place it in the empty fixer bottle. The agitation scheme is the same as for the bleach — agitate for 5 seconds every 30 seconds. Use the last 10 seconds of this step to drain the fixer back into the fixer bottle.

Wash #2

Set a 3 minute and 15 second timer and follow the exact same process as you used for wash #1. At the end of this wash, drain your tank.

Final Rinse

Pour the final rinse into your tank and set a timer for 1 minute and 30 seconds and do an initial agitation by inversion for 30 seconds. Clean the funnel and place it in the final rinse bottle. Wait for the timer to run out and pour the final rinse back into the final rinse bottle. I usually wet my squeegee in the final rinse while pouring this back into the bottle.

Drying and Cleanup

You did it! You’ve developed C-41 in Kodak Flexicolor! Go hang those negatives to dry. I use a squeegee to help with drying 35mm and 120 film. I get good results with my squeegee. That said, I get scratches when drying 4×5 film with a squeegee. Your mileage may vary. My usual drying time for the film is 3 hours, though depending on the season and humidity levels, I’ve needed as much as 4 hours.

Time to clean your equipment in soap and water and wait for the film to dry so that you can scan it.

Further Reading

It took me a lot of research on-line and talking to people about C-41 to finally arrive at this process. I’m sharing all of the resources that I found useful here:


    • Tank means 1L bleach at stock concentration. So 5L should last quite a while. Bleach really does last a long time. When you get a bleach bypass look, you know you’ve exhausted your bleach. If you get this, you *can* go back and re-bleach the negatives, rinse, and then re-fix to finish your processing.

      • Is there a way to identify a bleach bypass look without scanning? Can you show some examples? Also if I’m to be looking out for bleach bypass to know when it’s gone, can I also a ssume that the fixer is bad at this point also and needs to be replaced? Which one goes first? I think I read on here that fixer goes first (approx 80rolls to the bleache’s 100 rolls)?

        • I don’t have examples of bleach bypass. When your fixer goes bad, you’ll know it — the negatives will look a little milky and the scans will not have good contrast and will look quite poor. You won’t get near the dynamic range that you expect from your film if your fixer is bad. But you can always go back and re-fix. If you do re-fix or re-bleach, don’t forget to do all the rinses and re-apply the final rinse at the end. I’ve found that fixer goes first. I’ve mixed up 3 unique bottles of fixer and I’m only on my second bottle of bleach.

  1. Thank you very much for putting together this guide, especially the list of currently available chemistry.

    • I suspect you could do well with the C41 Bleach III Replenisher that you’ve mentioned (https://www.photoresource.com.au/KODAK-FLEXICOLOR-C41-BLEACH-III-REPLENISHER-p/6600258.htm), though I’ve not specifically used that one. That bleach has the same EKY number on it as this: https://www.uniquephoto.com/product/kodak%2Dflexicolor%2Dbleach%2Diii%2Dreplenisher%2D6600258/_/searchString/bleach%20kodak , which has the following description:

      “Develop photos with your film by using the Kodak Flexicolor Bleach III Replenisher. It contains one 10 l bottles of Part A and Part B in order to yield a total 10 l capacity. For added versatility, you may use this bleach as a replenisher or mix it with a starter to prepare a working solution. To restrict the amount of chemical discharge and minimize overall developing costs, you may also reuse the bleach overflow when it is used as a regenerator. ”

      That’s going to be a lot of chemistry — in particular given the yield. Comparing the notes on the box from photoresource.com.au and the above note from unique photo, I’d expect this makes 20L of bleach that you can use without a starter for C-41 development.

      If you give it a try, feel free to write back and let me know if it works — sure looks like it should!


  2. thanks so much for putting this together.

    some questions if that’s ok!

    1) is it worth doing a wash cycle between the DEV & the bleach, just to keep the bleach uncontaminated from developer?

    2) am I to understand that your working solution developer is only “one-shot”? discard after each roll developed?

    3) in your approximation, with these (roughly) $125 worth of chemicals, how many rolls can you develop?

    again, thanks so much for putting this together.

  3. and, follow up question based on question 2…

    2b) if the working developer is indeed to be tossed after using once, is there a reason you need to mix 1L of it at a time? or could you mix 300ml for one roll in a Patterson tank?

    • Howard,

      Thanks for your questions!

      1) Do NOT do a wash cycle between the DEV and the bleach. The bleach is formulated in such a way that minor contamination is not an issue and you will end up over-developing your negatives. I’ve tried this and things get washed out and have the appearance of having had at least 2 extra stops of exposure. It just doesn’t work well.

      2) The working solution developer is one shot. You could certainly mix working solution at the exact quantity you need using the ratio found on this site, which comes from Kodak’s guidance.

      3) It’s a tricky calculation because developer starter, bleach, and fixer are all going to last you a while. But you can get 6L of working developer with this set up and at 3 rolls 35mm or 2 rolls 120 / 1L (in the mentioned Paterson tank), that’s 18 rolls of 35mm and 12 rolls of 120. That’s $10.41/120 roll and $6.94/35mm roll. You can also get 6 sheets of 4×5 film in 1L and that becomes $3.47/4×5 sheet. However, it’s only an extra $13.95 for another developer replenisher kit and then you’ve doubled your capacity and dropped the per roll/sheet cost down quite a bit. Ultimately, you end up buying the developer replenisher kit a lot and the other chemicals just keep humming along until you exhaust them, which takes a long time. That makes this pretty economical, with the above prices being your worst economy.


      • When do you know that each chemical is exhausted? Can you explain for each chemical? Are you able to tell before you destroy a roll?

        • Developer matters most. Since you are mixing developer up one-shot, you are not going to run into re-use issues there. Many people have reported keeping developer replenisher in air-tight containers for over a year and still having it work. Kodak says 6 months after you mix it up, so on that one, there you go. Developer Starter has an expiration date on the bottle, but never really expires. After that, if your bleach is bad, you can go back and re-bleach. If your fixer is bad, you can go back and re-fix.

  4. Mad helpful. I agree about separating bleach and fixer…I try to get the best for my film as I can before I run it through the Frontier scanner. So it only makes sense to get the most out of the development process.

    Thank you so much, Karl. Lastly, I assume I can follow this exact method but with the Fuji Hunt X-Press chemistry, correct?

    • Trenton,

      Given that C-41 is a standard process (in which you could do Fuji Developer, Kodak Bleach, etc.), you should be able to use the Fuji Hunt X-Press Chemistry. The biggest thing to double check would be the temperature and times of the developer. That *may* be different. Everything else should be more or less the same.


  5. thanks for the lengthy reply. I think I’m gonna try this based on how you’ve really made it seem so easy, and it definitely seems like a step up from the Blix based kits out there. the only change I see making to your workflow, is that I think I’m going to keep my Developer Replenisher in 20 x 250ml bottles. as I only really ever develop one roll at a time, that way there would been no need for measuring or recuperating excess chemicals…if my math is correct 250ml replenisher plus 10ml starter plus 60ml water would yield 330mls of working developer, which is perfect for 1 roll of 35mm in the paterson.

    hey…while we’re at it…with the Sous Vide…do you find that the chemicals inside the bottles take a while to match the water temp in your bucket? maybe I’ve had bad luck, but I find glass bottles “insulate” slightly, and often I have to make the external water 10 degrees warmer than I want the chemicals inside the glass to reach.

    thanks again for all the work you’ve put into this.

    • Howard,

      Sounds like a plan on the smaller quantities! Regarding the sous vide, it does take some time for this come up to temperature. For me, it probably takes between 40 and 50 minutes. In the past, I have tried the setting the sous vide higher method and because of the “insulating” characteristics of the glass bottles, it actually takes longer for the temperature to come back down than it does for it to go up. As such, I just set mine at 100.4F and play the waiting game.


      • I would concur with the set it and give it time method, not the extra-hot overshoot method. I give my chems a good hour to come up to temperature. Use the glass thermometer to confirm they are ready.

  6. You mentioned that the final wash doesn’t have a stabilizer. Is there a way to modify this process for expired, pre-2002, films?

    • So I found from PE on Photrio the following stabilizer recipe:

      ” Mix up Photo Flo 200 as directed on the bottle. To one liter of this add 3 – 10 ml of 37% Formalin solution. That is it. The reason for the spread is that I have found several formulas with values like that. I use 10 ml to be on the safe side.​”

      source: https://www.photrio.com/forum/threads/what-substitue-for-kodak-flexicolor-sm-tank-final-rinse-stabilizer.154756/

      Formalin is formaldehyde and I’m not sure where you would get that or if you really want to use that (I personally wouldn’t). Your best bet may be to buy a C-41 kit with stabilizer in it, mix up the stabilizer and then use that until it gets dark. You can certainly use that stabilizer for more than the 8 rolls that those kits typically advertise they’re good for. I know I have used that stabilizer before and it works well enough.


  7. just circling back to the question about the bleach. your shopping list just lists the replenisher, and not the bleach starter. I am assuming because the undiluted bleach replenisher serves the purpose of the starter plus replenisher? thanks again!

  8. Thanks for the great write up, it’s very helpful. I recently developed my first C42 using Cinestill simply because it was available locally and convenient. I had found some of the info about using Kodak chemistry but was confused about exactly what to buy. Just ordered everything from Unique. Thanks again for the great write up and all the links.


  9. This was incredibly helpful, thank you for sharing this wealth of knowledge! I’ve been trying to work this out for months!

    Based on both what you have up above, prices, from Unique Photo (including shipping) and the Z131 doc, I came up with the following – wanting to make sure this sounds right?

    Per Item Cost:
    35mm/36 exp: $4.23
    120: $6.34
    1 4×5 Sheet: $1.59

    Does this sound sensible to you? This is based on Kodak’s capacity info (page 3-5 of Z131) which I would guess is also conservative. I took those capacities along with the prices of the chemicals including shipping (assuming always buying all these at the same time) and then calculated the per-liter cost based on the capacity of the dev and other chems (noting the other chems are 2x the capacity – I suspect final rinse is much higher than that as well). I then calculate the individual item cost based on the more conservative table on Z131.

    Above is certainly cheaper than a lab when you account for shipping back and forth and the time. My only hangup is the developer isn’t very concentrated and requires more chemistry than I was hoping for. I use a DIY rotary process (using a Jobo 2500 with an Arduino powered 3D printed rotary I made). It is ok for 500ml but tends to get a little wonky when using chemistry up to the 1L mark. Plus that much chemistry takes more time to fill and drain. But still it’s perhaps a worthy trade-off!

    • The numbers certainly don’t sound wrong. Developer Starter will combine with a significant amount of developer replenisher and since the starter doesn’t go bad, you don’t buy that very often. Arguably, you get to a point with the chemistry where you stop counting and just buy what you need when you need it. Typically, you’re buying developer replenisher. All the other chemicals need to be repurchased on a much longer schedule. I get 3 rolls of 35mm, 2 rolls of 120, and 6 sheets of 4×5 per 1L of developer (763mL dev rep + 30mL dev starter). The bleach runs for ~100 rolls and fixer runs closer to ~80 rolls or so? I certainly haven’t kept track, but can tell you this stuff lasts a long time. One of my gripes with the C-41 press kits is you mix the developer and the instructions tell you to use it in 7 days and for no more than 8 rolls. So you have to batch your C-41 and buy/mix a kit for each “run” of up to 8 rolls. With the Flexicolor setup, I let developer replenisher sit on the shelf and don’t worry about the timing on it. I usually use it within 6 months as I do a decent bit of C-41, but others have reported success in letting it sit for a year.

  10. Thanks for putting together this guide!! I have been using the method you described with the same chemicals. However, I use bleach started for the Bleach replenisher RA to make working solutions as per Kodak Z131 instructions. The bleach starter is the most expensive chemical I use- is there any reason why you don’t use it? Regards from Mexico!

  11. Question…I know the working developer is meant to be “one shot”….but has anyone experimented reusing it? Either right away from one Paterson tank to another, or in a bottle and used the next day? As you say above, the developer replenisher really is the consumable, and if the working solution can be used, even twice, that practically cuts costs in half.

  12. oh, also, in response to your question about the fixer you linked above…it arrives in a 5L container, and you mix it 1:1 with water, to get 10L of working fixer

    • How do you store the fixer? Should I mix and store it all in 1L bottles (or something equivalent) or can I get away with mixing 1L at a time and leaving the remaining fixer in its original bottle?

  13. Karl, first off, thank you for this fantastic guide. I’ve been struggling to source a C-41 dry kit thanks to COVID-19 and everyone taking up the home developing hobby! In the past I used the Unicolor C-41 kit that used Blix, but I don’t mind the added complexity of separate Bleach and Fixer… being an engineer I assumed there was a trade-off being made, but I just didn’t know where to start. Your Kodak links above will now keep me busy!
    A comment on the Sous Vide power rating or “water capacity”… It is really all about the water temperature you wish to be at, the ambient temperature of the room it is in, and the level of insulation you provide. The “rating” they give may be at a much higher temperature for cooking meats. I wouldn’t worry at all about how much water you put in your bucket. I have wrapped my water bath container in an adhesive backed neoprene foam layer in hopes of even temperatures across the dimensions of the bath. You could always throw a towel around your bucket if you were concerned, but it’s all nerd level micro-tweaking at that point. If your bath bucket stacks with others, another cheap insulation trick is to simply stack two together, providing a thin insinuative air pocket between them.
    Thanks again for the guide and material links. Some of the Q&A with other readers above was useful to me as well as I had similar questions. Especially your comment about not washing in between the developer and bleach steps.

    • Follow-on question [sorry]. I noticed you don’t pre-wet your film. Simply heat up the film and tank by immersion for a period of time. Is there any reason you don’t pre-wet with 100deg water? I’m just curious, as I see the merit from a thermal point, but not sure if the water entering the emulsion makes it more difficult for developer to be taken in by the emulsion, leading to undesirable results. I’ve been pre-washing my B&W films before developing with warm water mainly because the wash water comes out so nasty. I don’t recall if I read to do that or not in the Kodak D-46 guide and I did see some level of disagreement about doing it or not online. I’ve only been doing this for about a year so I’m still learning everything and I appreciate your help and advice.
      Tony Moreno
      San Diego, CA

      • Pre-wetting B&W film works fine and I do that all the time. Pre-wetting C-41 actually causes the developer to not correctly hit the emulsion. I’ve pre-wetted C-41 before and can’t remember if there was a negative effect, but I read on photrio that you shouldn’t do that, I stopped doing it, and I’ve not found a reason to change. The Kodak documentation is pretty clear on not doing a pre-wetting stage with C-41.

        • The new Jobo 2020 catalog calls for a pre-wash for color film. “In this context it is helpful to remark that JOBO clearly recommends to always pre-wash your film (and paper) in rotary processing for 2 to 5 minutes. Pre-washing allows the emulsion to soften up and absorb first water molecules. Keep in mind that, different from inversion processing, in rotary processing chemistry does not hit the whole film surface at once. Pre-washing makes sure that chemical is evenly absorbed by the emulsion in rotary processing of your film (and paper), avoiding unevenness and undulations on the film surface. Our service department found that 99% of customer complaints with unevenness were strictly correlated to the lack of pre-wash. Color-processing times remain unchanged even with pre-wash, whilst B&W development times need to be increased by an average of 20% compared to B&W development without pre-wash.
          With inversion processing the pre-wash can be skipped as the whole film is always simultaneously immersed in chemistry. Due to the reduced agitation in comparison to rotary processing the development times are about 25% longer for inversion processing than they are for rotary processing to achieve the same density. As a rule of thumb, you can say that developing film in rotary processing with pre-wash will take about the same time as inversion processing without pre-wash at any given temperature. Most large format photographers know about the challenge of achieving evenness of processing when working manually. The larger the film format the greater this challenge becomes. Apart from perfect control of push & pull process, the evenness is one of the main reasons why a large format photographer should opt for the JOBO processor with Expert Drum.”

          • Thanks for that from the Jobo 2020 catalog. That’s a fascinating point about the difference between rotary and inversion processing and where a pre-wash is helpful versus where it is not.

  14. Thanks for putting this post together. It’ll nicely complement my own notes (from various Photrio threads and scouring the Unique Photo website) for when I’m finally ready to switch to Flexicolor myself.

    At the moment I’m working my way through a Fuji X-Press C-41 kit, which is probably the next best thing. Also, I am actually one of those people who bought a box of control strips and measures them with a densitometer. I’ve been keeping a spreadsheet of the data, and been attempting to analyze it per Z131. So far I’ve gotten good results out to the 9-month mark. I hope to do another test at the 1-year mark soon, after which I’ll put together my own blog post and/or video on the results.

    I’d cautiously agree with those people who say that the stuff is actually good after a year, but my crazy testing regime has given me the comfort of not having to take this on faith.

    • Thanks for the verification with the control strips! That’s excellent to get real data behind the length of time that you can let these chemicals go.

    • Yes thank you!
      It’s good after a year as concentrates in opened bottles? Or are you mixing working solutions and having them sit in glass bottles? Or are you doing something else?

  15. opening this question up, not only to Karl, but the other posters as well.

    for the past year I’ve heated my c-41 chemistry up in my sink…filling up the sink with the hottest water I have, and immersing the chemicals into said sink in measuring cups, and stirring the solution until it hits 100F. normally this is a 10-15 min affair.

    I was able to speed up the process greatly by using aluminum measuring cups instead of plastic, but then I got paranoid that the chemicals & the aluminum didn’t play well together (can anyone confirm this?).

    I have not compared the heat transfer speed between glass & plastic measuring cups, so I wonder if I can speed up the process by switching to glass.

    but but…this past weekend I had a bit of a breakthrough…

    I mixed the Developer Replenisher into 20 x 250ml bottles, so that I can just grab a bottle for every roll of 35mm, and not worry about measuring (it’s all been pre-measured). so, I took 254ml of replenisher & mixed it with 10ml of developer starter…put those in a measuring cup and put It in the sink immersed in hot water. the starting temp of these two chemicals was 67F. then I went and spooled my film on the paterson reel, and when I came back, about 2 mins later, the developer mixture was at 78F. to this, I added 69ml of boiling water (which started at 212F, but quickly descended to 188F once it left the kettle, and, almost like magic, the newly mixed working developer was at 100.4F.

    I know there’s a lot of variables here that are out of my control…room temperature, the temperature of the chemicals soaking while I spool off the film, etc…but, in principal, am I doing anything wrong/forbidden by working this way…either by holding off on adding the water to the starter & replenisher, or by using boiling water?

    second question…I’d be curious to know everyone’s temperature readings of the C-41 developer at these three instances: 1) before pouring into developing tank (theoretically 100F), 2) immediately after poured into said tank, 3) at the last 15 seconds of the development process.

    try as I might, I can’t get the temperature to stay at 100F from start to finish of the development.

    thanks in advance, and thanks again to Karl for starting this amazing thread.

    • Howard, I will measure the exit temperature of my developer chems next time I do a run and see how much they dropped. However, my development tank is in a controlled water bath, so my expectation is that it will come out at the same temp that it went in. I don’t think the development stage is exothermic or endothermic by any appreciable amount. Do you place your paterson tank in your sink bath in-between agitations?
      Regarding aluminum, it may be sufficiently passive enough to not react enough in a way that you would notice. Stainless steel is less passive, but thermally more restive. Glass and plastics are the most chemically passive, but also thermally insinuative. Bear in mind that wall thickness plays into the container’s heat transfer properties. A thin walled plastic container will pass heat into solution faster than a thick walled glass one… but glass containers are heavier and may submerge more in your bath! that translates to more heat transfer area!
      It sounds like you are using kettle water to warm your bath and chems rather than a temperature controller. This means your bath will swing up and down in temperature quite a bit. Speed of heat transfer and aggressive stirring strike me as your most important requirements. The aluminum containers are probably good. I suggest something large with a lot of surface area for fast heat transfer. Stir it aggressively and remove when your desired temp is reached.

  16. Are you using your black kitchen scale to measure out 763mL by using the density of water at 1gm/mL? I finished reading the linked Kodak datasheets and purchased my chems the other night. and I’m getting a few chemistry lab supplies tonight from a local supply house. Looking forward to trying this LU method out. Even though Kodak very clearly states that the rotary process is one shot, I’m curious to test out using the remaining 237mL of developer replenishment solution and try three additional runs at a 75mL replenishment rate (I have a 2 x 120 roll Patterson tank). I wonder if the tank inversion agitation steps rapidly oxidizes the developer, turning it into a one shot process. Further, can I game the system by performing a nitrogen purge of my development tank prior to adding the developer in? Questions that I’m excited to experiment with and try to determine.

  17. hi Tony…

    Thanks for your reply. I can confirm that, by using a thin walled borosilicate glass beaker, my chems got to temperature far faster than by using a plastic measuring cup. the heat transfer speed rivalled the aluminum cups I was using. I’m definitely considering picking up a sous vide, or even that cinestill temperature controller, so that I have more consistency. and on the subject of cool film toys, I stumbled upon this today:


    certainly makes the long development times of, say, having shot tri-x at 1600, a little easier without having to worry about all the agitation.

  18. Oh how I wish this was as economical in the UK! After much shopping around the best I could find was from Tetenal UK and it came to $520 just for the chemicals!!! The Primary reason is that the quantities are much higher eg; you can only buy the developer in 4x10l quantities. Im sure if I had an absolute monster load of C-41 to process all in one go then it might be logical to go down that path. But as much as I would love to shoot more I don’t even get near 100 rolls a year these days to my detriment I must admit.

    Luckily for me though I can buy 5l kits from both Fuji-Hunt and Rollei that are separate bleach and fix and only cost about $62 and will process about 100-120 films a pop which I think is a fairly good price to performance ratio.

    It would be fairly interesting though to compare the results and see if there is any true discernible difference between films processed with either method.

  19. I just ordered the listed chemistry and have a question. Is it possible to only make 1L batches of developer while leaving the remaining concentrate (A, B, C unmixed) in original bottles until a new batch is needed? I don’t want to keep 5x1L bottles that i may never completely use sitting around. If so, can anyone provide the measurements? Or is it as simple as dividing each part by 5? Thanks.

    • I’m not sure how well the individual components would keep if mixed only to 1L of developer at a time. Mixing the 5L up doesn’t take too much and you can let these bottles sit for quite some time. Considering that you only use this stuff in a one-shot mode, that means you’ll only be able to develop 6 1L tanks for every 5L of developer replenisher that you mix up. If you aren’t shooting enough C-41 to make it worth your while to do 6 tanks in a 6-12 month period, then you may want to look into buying a C-41 Press Kit to get the developer from that. That makes exactly 1L that you use for up to 8 rolls of film, but it has a lifecycle on it of 1 week. (Others have done more rolls and have kept it for longer, but the numbers I’ve provided are the official recommendations.)

      • Yes you can mix up 1 liter quantities at a time, I’ve been doing it for the past 5 years. Kodak actually wrote a great manual for how to do it.


        Also, I’ve seen that you use the kodak lorr dev rep as a one shot which seems like a waste, Kodak has specifically made the lorr developer replenisher as a way for minilabs to have lower replenisher rates and a longer lifespan on the developer.

        Using Kodak lorr developer you replenish the tank solution with 33.1 ml per roll.

        Technically you need to replenish your bleach tank solution with 69 ml per roll.


        Go to section 3 page 4 to see the chart of replenishment rates.

        Its a great system but there’s no need to waste all that replenisher. I usually change my fixer and final rinse once they start to get discolored, I do both of them at the same time. The developer I hardly ever scratch the whole thing, maybe once a year, I just replenish it same as the bleach.

        Example: Say I develop 4 rolls of 35mm, I will measure out 33.1 ml x 4 rolls = 132.4ml I don’t worry about being exact, usually I will round up to be liberal lets say 135ml. So measure out 135ml dump it out and then add in 135ml of fresh replenisher, at this rate your lorr dev rep will last much longer and the replishment system ensures quality.

        • Ler, thank you for this bit of advice. So basically, once you get the developer started, you can do this to really reduce the amount of replenisher that you use as opposed to doing this one shot. How long do you find the developer solution stays stable? I could definitely see employing this method for doing a few tanks back to back, but can I then keep my developer for a month or two and continue to use it? Or at that point, should I mix new and start over?

  20. Thanks Karl for the article. I have a rather lengthy comment that might be of help to some who ask about the chemical stability. For many years, I processed B&W and stored the Dev, Fixer in glass bottles with the hard black rubber laboratory stoppers. And I had very good stability. But when I began to venture into C41 and decided to upgrade(?), I replaced these with plastic bottles which were Poly Ethylene(PE) plastic. I noticed my stability wasn’t what I expected with C41 chems but also my B&W chems were also less stable in these PE bottles. I found out later that PE plastic allows a lot of oxygen to diffuse thru the walls of the bottle. I went back to glass and the stability improved greatly. But it began to be hit or miss. One bottle would last, and another bottle would be much more oxidized. I traced it to the caps of the glass bottles. The paper liner in the caps was not working well it seemed, since the newer the bottle the better the stability and possibly the seal. I tried plastic liners, foil liners, foam liners, and even teflon liners in the caps. What I think I found was, that as the cap liners were worn from opening and closing there wasn’t a tight enough seal and the chems were pulling in air from the cap liners even when very tightly closed. The old rubber stoppers, as the vacuum developed, the stoppers were pulled in and the seal actually became tighter. We all have seen old developer or fixer plastic bottles that are distorted due to age and the, what I assume is, extreme oxidation taking the air out of the bottle’s air space. So while glass seemed the best for storage, the caps themselves were a major problem. I didn’t want to go back to the rubber stoppers so I investigated plastic and found that PET plastic was almost as good as glass with regard to reducing oxygen permeation. And that almost all water or soda bottles are PET plastic. The caps themselves not having a real liner can seal very tight, as shown by how well they can keep the carbonation from diffusion thru the plastic even under the pressure the gas exerts. So I switched to 1 L seltzer water or tonic water and 2 L soda bottles. The stability has been consistent and fine since the switch.
    As another note – I stopped using distilled water for limited chemical mixing a long time ago and went to tap water taken from a faucet without the aeration screw-on on the faucet. No need to add more air into the water. Then someone offered me a laboratory water purification panel which I thought would be useful (the panels that hold three cartridges). What I found was my B&W negs were weak and less contrasty when processed with DEV mixed with the lab quality water. I confirmed this by testing plain tap water again. I traced the problem to the deionizer cartridge in the lab panel. I replaced the deionizer cartridge with a charcoal cartridge. So I filter thru two charcoal filters and a sediment filter. The filters are changed around every 9 months, and I use this water as a final rinse off for all processing equipment before drying. This has been easier than storing and carrying gallons of distilled water which I always seem to run out of at the worst time. The charcoal filters remove most of the organics and are claimed to have a life of around 300 gals.
    Anyway, those are my opinions and I haven’t seen any issues with processing in this manner.

  21. I’ve been reading all I can about the flexicolor chemistry and would recommend doing that for everyone about to attempt using this process. Kodak publishes a white paper called z131 that’s meant as bible for flexicolor. It can be challenging to navigate this technical document at first but it provides all the information necessary to use the various formulations of this process that kodak manufactures. I think the effort to publish this quick guide by kabbottphoto is formidable but unfortunately it presents some misconceptions and mistakes that should be addressed. It follows the instructions for the flexicolor formulation made for small tanks that kodak discontinued a few years ago. Because of this, there are two major errors that it promotes. First, some processing times for the chemistry are innacurate (for example, for this specific formulation of bleach that he’s using, the processing time should be just 1 minute). Second, it presents the use of this chemistry as one shot when in reality, and as the names of the steps indicate, this formulation is meant to be replenished after using it to develop a certain area of film. This is probably the major way in which the process for small tanks and this one for minilabs deviate, since the formulation for small tanks is meant to be tossed and the one for minilabs is meant to just create a small amount of discharge that you are meant to be constantly replacing with fresh replenisher. Take this present quick guide as a starting point to learn how to mix and to get a general idea of how the process works but just keep in mind that the formulation you can purchase nowadays is not meant to be used at home and so you do need to do a bit of reading to learn how to best adapt for a smaller scale developing. The processes are not drastically different, but there’s a reason why the small tank guide is just 4 pages long and the one for large scale flexicolor is 97.

  22. Hey Karl,

    Do you think if I did the math and made 500ml concentrations of everything I’d get good results? Have you already tried this? I’m planning on using these chemicals in my Filmomat Machine!

    • Kodak has a document about mixing these chemicals in small quantities. The main formula you would need to do the math on would be the 763mL dev. rep. + 30mL dev. starter + h2o. Their document is here: https://125px.com/docs/chemicals/kodak/cis49-2009_12.pdf . Certainly haven’t tried making smaller than 1L formulations, but suspect that this would work. Worst case, you could mix up 1L of developer, split it into 2 500mL containers and then develop 2 tanks worth.

  23. if i triangulate Mariano Madrigal’s comments, as well as Ler’s, and referring to the Kodak z131 paper, this is what i deduce. please chime in if i am mistaken:

    -the bleach Karl recommends using is the RA version, which was in fact created for the C-41RA process used in minilabs. as such, it’s meant to be used for 1 min at 38 degrees (+/- 3 degrees), and be subject to heavy agitation. (from table 4-1 of the white paper). i wonder if this discounts it being used in the manner Karl is suggesting. I have heard you can’t really “over-bleach” in terms of time, but if it would achieve the same goal by raising the temp, and lowering the time, and agitating more, i’ll happily take that extra 5:30 saved.

    -using the DEV REPLENISHER as a one shot is wasteful. does this mean…if one is developing in a tank…that we should do our first roll with 100% DEV STARTER, and then replenish that 1.2L bottle with the respective amount of replenisher each time we develop another roll?

    in any case, i know, in some ways, using this chemistry at home is a bit of a “hack”, in terms of the application the chemicals were designed for…but, in the end, the procedures Karl outlines do indeed work, and, personally atleast, yield better results than any of the blix based kits i’ve used.

  24. Thanks so much for this guide, it’s been so helpful. I have just ordered my batch of Flexicolor 5L chemistry and plan to give it a shot. The one exception is I can’t seem to find in stock Final Rinse? Is it feasible to just use PhotoFlo or another Final Rinse from another C-41 process? Just wanted to confirm. Thanks again.

    • You could definitely use another final rinse from another C-41 process. I wouldn’t recommend using straight PhotoFlo as it doesn’t have everything needed to protect C-41 film for the long haul.

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