Selecting a good C-41 kit / Separating blix into bleach & fixer.

dcy · May 17, 2025

Hi everyone,

I've been lurking the forum for some time. Now I want to ask a couple of questions. I was reading a thread from last year. In this comment koraks says that he considers powder C-41 kits to be second rate and "all quality C41 chemistry comes as liquid concentrates." A little later he explains that the issue is that they are blix-based kits (i.e. they don't have a separate bleach + fix).

Question 1: I am familiar with the problems with blix. Aside from that, is there any other downside to powder kits? The reason I ask is that the Rollei, Arista, and Tetenal (now reborm as Adox) C-41 kits are all liquid kits that have a blix instead of a separate bleach + fix. In other words, I am wondering if all of those options are equally sub-optimal.

Question 2: "Blix" usually comes in 2 or 3 parts. Can I just... not mix them and treat them as a separate bleach & fix? To attempt this, I need to figure out which part is the bleach and which one is the fixer. The Rollei and Adox/Tetenal kits have a blix in 2 parts. If you read the MSDS you'll see that:

1) For Rollei, Part 1 has a "European waste catalogue" of "bleach solutions and bleach fixer solutions" while Part 2 says "fixer solutions".

2) For Adox/Tetenal, "Ammonium thiosulphate" is listed under Part 2, so that must be the fixer. Part 1 includes a molecule with a long complicated name that looks like a cousin of PDTA and EDTA which usually is part of the bleach.

So I could keep Parts 1 and 2 separate and add water to each. Because bleach and fix are both "to completion", I can be conservative and leave the film in each bath for a few extra minutes.

Would this strategy work?

Thanks for the help.

koraks · May 17, 2025

dcy said:
I was reading a thread from last year. In this comment koraks says that he considers powder C-41 kits to be second rate and "all quality C41 chemistry comes as liquid concentrates." A little later he explains that the issue is that they are blix-based kits (i.e. they don't have a separate bleach + fix).

That's part of it. The other part is that the powder-based kits usually consist of a non-standard developer (e.g. Cinestill Cs41). If powdered chemistry would be a feasible option to get lab-standard quality, the industry would have adopted that decades ago. The fact that they settled on (usually) 3-part liquid concentrates indicates that this is really the only feasible way to provide consistent and excellent results at reasonable costs.

You could theoretically make a powdered kit that would perform to spec, but it would involve packaging and mixing challenges that would not work well for amateur/home lab settings.

So my main concern is really with the developer in these kits. The blix is a secondary issue.

dcy said:
Can I just... not mix them and treat them as a separate bleach & fix?

Many people have done this and to the best of my knowledge with good results. The main concern would be that you may not hit the perfect pH for the bleach, but as you said, that is supposed to go to completion and besides I'm pretty sure it has considerable leeway in terms of pH anyway, I wouldn't worry too much about it.

You could always do a test to see if it works well for your process. Take an unexposed and unprocessed strip of color film. Run that through your color fixer (or even a B&W fixer). It should clear into a typical orange CN base. Now take a strip that's entirely fogged (daylight is fine), then develop it in a B&W developer (print developer is OK). Then run it through your separate bleach and fix steps. This strip of film should have virtually the same base density as the control strip that you only ran through the fixer.

dcy said:
Because bleach and fix are both "to completion", I can be conservative and leave the film in each bath for a few extra minutes.

Yes, that's right.

khh · May 17, 2025

The kits with separate bleach and fix aren't much more expensive, though. In your shoes, I'd just get one of those, that's what I've done. Kodak's, Jobo's, Bellini's and Fuji Hunt X-press are all excellent.

Truzi · May 17, 2025

This resource posted by Rudeofus may prove helpful:

Converting C-41/E-6 BLIX into Separate Bleach and Fixer

1 Introduction Many C-41 and E-6 kits come with BLIXes to remove silver. These BLIXes sometimes don't work all that well, and some of the BLIX concentrates have limited shelf life. The main purpose of this document is to provide a brief...

www.photrio.com

blee1996 · May 17, 2025

There are plenty of liquid C41 kits that have separate Bleach and Fix, for example the resurrected Kodak C41 kits that's inexpensive and available everywhere in the US.

dcy · May 17, 2025

koraks said:
That's part of it. [ ... ]

Thanks! That was really helpful.

dcy · May 17, 2025

khh said:
The kits with separate bleach and fix aren't much more expensive, though. In your shoes, I'd just get one of those, that's what I've done. Kodak's, Jobo's, Bellini's and Fuji Hunt X-press are all excellent.

Kodak, Jobo, and Fuji Hunt are 2.5 - 5L kits. I have never developed C-41 and I only shoot about 1 roll/week (or slightly less) including B&W and C-41, so I am concerned about the C-41 chemistry going bad. So I'm mainly looking at 1L kits.

Bellini makes a 1L kit and basically I am torn between Bellini and Adox. They cost about the same ($44 vs $38.50 from Freestyle photo) and both make 16 rolls, which is the most I think I can manage.

As you said, Bellini has separate bleach + fix. My concern, again, is longevity. Bellini gives you a pre-mixed bottle of developer concentrate. They say that an open bottle of developer concentrate is good for 4 weeks.

In contrast, Adox keeps the developer in the usual 3 parts and they say that the unmixed-but-open bottles are good for 12 weeks. That gives me a lot more flexibility to arrange development sessions without the developer going kaput. So that's why I'm eyeing Adox.

koraks · May 17, 2025

You can keep most c41 developer for a very long time mixed working strength and stored in airtight containers. This means glass or something like PET or the kind of bladders used for wine. It's important to ensure there's no air on top of the liquid in the container. I keep my Fuji Hunt C41 developer fresh this way for well over a year.
My film consumption isn't all that much higher than yours btw.

dcy · May 17, 2025

Truzi said:
This resource posted by Rudeofus may prove helpful:

Converting C-41/E-6 BLIX into Separate Bleach and Fixer

1 Introduction Many C-41 and E-6 kits come with BLIXes to remove silver. These BLIXes sometimes don't work all that well, and some of the BLIX concentrates have limited shelf life. The main purpose of this document is to provide a brief...

www.photrio.com

Wow. Thanks! Yes, that looks super helpful.

blee1996 · May 17, 2025

Air-tight and light-tight aluminum foil lined wine bladder (pouch) can keep mixed C41 chemical fresh for years. I have done that for larger 2.5L/5L kits.

dcy · May 18, 2025

koraks said:
You can keep most c41 developer for a very long time mixed working strength and stored in airtight containers. This means glass or something like PET or the kind of bladders used for wine. It's important to ensure there's no air on top of the liquid in the container. I keep my Fuji Hunt C41 developer fresh this way for well over a year.
My film consumption isn't all that much higher than yours btw.

Thanks for the tip!

I know the glass bottles you're thinking of. I use them for B&W chemistry. I'm going to grab a few more and I will also buy one of those inert gas products people use to displace oxygen. I'm going to start with the Bellini kit, and if I manage to not screw up the developer, I will aim to eventually move to one of the 2.5L and 5L kits from Kodak and Fuji.

mshchem · May 18, 2025

dcy said:
Thanks for the tip!

I know the glass bottles you're thinking of. I use them for B&W chemistry. I'm going to grab a few more and I will also buy one of those inert gas products people use to displace oxygen. I'm going to start with the Bellini kit, and if I manage to not screw up the developer, I will aim to eventually move to one of the 2.5L and 5L kits from Kodak and Fuji.

This sounds like a good strategy.

koraks · May 18, 2025

dcy said:
I will also buy one of those inert gas products people use to displace oxygen.

I don't use it and frankly, I don't put much stock in it either. The 'seal' this creates is very imperfect and temporary. A more dependable strategy is to buy relatively small bottles (e.g. 300ml or so) and ensure they're entirely full until you open one to use it up.

dcy · May 18, 2025

koraks said:
I don't use it and frankly, I don't put much stock in it either. The 'seal' this creates is very imperfect and temporary. A more dependable strategy is to buy relatively small bottles (e.g. 300ml or so) and ensure they're entirely full until you open one to use it up.

I can do that! Thanks.

Samu · May 23, 2025

koraks said:
That's part of it. The other part is that the powder-based kits usually consist of a non-standard developer (e.g. Cinestill Cs41). If powdered chemistry would be a feasible option to get lab-standard quality, the industry would have adopted that decades ago. The fact that they settled on (usually) 3-part liquid concentrates indicates that this is really the only feasible way to provide consistent and excellent results at reasonable costs.

You could theoretically make a powdered kit that would perform to spec, but it would involve packaging and mixing challenges that would not work well for amateur/home lab settings.

So my main concern is really with the developer in these kits. The blix is a secondary issue.

This problem with some of the kits seems not to be limited to powder based kits. For instance, all of the CineStill kits have developers, that use a different temperature and time compared to the standard C-41 process. And their E6 is totally non standard, to a point ehrte no references by Kodak or Fuji for troubleshooting are of any use. That said, the original Tetenal C-41 kit was not terribly bad when I tried it in the late 1980's. Adox claims their kit is the same. For E6, my personal experience with blix kits are worse - there have been issues with retained silver needing re-blix, and issues with stability of colors (after 20 years or more) when compared to slides processed in standard E6. In my experience, the blix is a bigger problem in E6 than it is in C-41.

One thing I have always wondered with CineStill, who advertises 3:30 developing time in 39°C, is that whether the developer is nonstandard, or are they just trying to compensate for people not heating their Paterson tanks during the developing stage. You have the YouTube full of young beginners controlling meticulously the temperature of their chemistry, but as they pour it in the tank, they just let it cool down on the table.

For me, Fuji Hunt is the obvious choice, as it is easy to buy their C41 and RA4 products here in Lithuania locally. And thy are probably the best products in the market.

Light24bulbs · Saturday at 12:30 PM

For all the people saying it's easy to find kits without blix: I can't find a single 1L kit for sale in the US without blix at the moment. Bellini is out of stock and that seems a semi-permanent thing for them, with only one US supplier I can see. Jobo and Fuji Hunt are both 5L kits and Kodak is more reasonable at 2.5L but still larger than I actually need. Pretty odd.

You have to think that if these manufacturers realized that longevity was the main thing keeping people away from C41 development at home, they'd make a small kit designed for longevity and explain how to make it last 6 months, which is obviously possible, instead of two weeks. Bizarre.

dcy · Saturday at 3:35 PM

Light24bulbs said:
For all the people saying it's easy to find kits without blix: I can't find a single 1L kit for sale in the US without blix at the moment. Bellini is out of stock and that seems a semi-permanent thing for them, with only one US supplier I can see. Jobo and Fuji Hunt are both 5L kits and Kodak is more reasonable at 2.5L but still larger than I actually need. Pretty odd.

I haven't gotten around to buying my C-41 kit yet --- I wanted to try a different lab first --- but I plan to buy it "soon" and I did notice that Bellini is out of stock.

My current plan is to get the Kodak kit. As you said, it's the next smallest. At least Kodak makes it clear that you can do partial batches as long as you're careful to keep the proportions the same. On the other hand, PSI (the company that makes the Kodak-branded kit) doesn't make that easy:

The 2.5L of developer includes 188 mL of Part A, 43.8 mL of Part B, and 94.6 mL of Part C.

And I'n supposed to divide those?

My current plan is to transfer those to glass bottles and add distilled water to make them 200 mL, 50 mL, and 100 mL and hope that the small excess dilution doesn't significantly shorten its life.

Light24bulbs said:
You have to think that if these manufacturers realized that longevity was the main thing keeping people away from C41 development at home, they'd make a small kit designed for longevity and explain how to make it last 6 months, which is obviously possible, instead of two weeks. Bizarre.

Up until just a couple of years ago, a Chinese company called Sino Promise owned the rights to make Kodak-branded chemistry and they didn't make anything for homeowners at all. They only made a product called Flexicolor where you'd buy a bottle of just the developer for $140 and it'd make 40 liters. --- Clearly intended for labs.

When Sino Promise went bankrupt, the rights reverted back to Kodak, who then licensed them to a well-regarded state-side company called PSI. To my immense joy they decided to make kits for the home user.

In this post @MattKing wrote a really interesting account of how all this happened.

As for why PSI doesn't make a home kit smaller than 2.5L ... I don't know. If I was being cynical I might imagine that PSI doesn't want Kodak's kit to compete with PSI's own small kit (Unicolor). If I am being charitable, I would say that perhaps PSI honestly feels that the market for small kits is saturated.

mshchem · 2025-08-10T00:35:55-0400

I would recommend making up all 2.5 L and splitting it up into 5 full 500ml bottles. Or something similar. You can develop 3 or 4 films in each 500 mL then toss.

koraks · 2025-08-10T03:24:46-0400

mshchem said:
I would recommend making up all 2.5 L and splitting it up into 5 full 500ml bottles. Or something similar. You can develop 3 or 4 films in each 500 mL then toss.

Yep, that's what I do. Works great. The developer keeps ages that way.

dcy said:
The 2.5L of developer includes 188 mL of Part A, 43.8 mL of Part B, and 94.6 mL of Part C.

And I'n supposed to divide those?

The part with the CD4 developing agent generally doesn't keep well once you've opened it. Some people report it stores OK if you decant it into a smaller bottle with no air on top. My experience is different. I'd not risk it as it basically means you risk losing much of the kit after a first use.

dcy · 2025-08-10T03:57:51-0400

mshchem said:
I would recommend making up all 2.5 L and splitting it up into 5 full 500ml bottles. Or something similar. You can develop 3 or 4 films in each 500 mL then toss.

koraks said:
Yep, that's what I do. Works great. The developer keeps ages that way.

The part with the CD4 developing agent generally doesn't keep well once you've opened it. Some people report it stores OK if you decant it into a smaller bottle with no air on top. My experience is different. I'd not risk it as it basically means you risk losing much of the kit after a first use.

Wait... Something doesn't make sense here. You said that making the 2.5L and decanting it into smaller bottles keeps ages, but you also said that CD4 by itself doesn't week well even if you decant it...

It sounds like you're saying that CD4 lasts longer in solution than by itself. That can't be right. The reason they're split up in the first place is that some of the other ingredients react with CD4.

Have I misunderstood something?

EDIT: In post #8 you mentioned that you keep your Fuji Hunt C41 developer fresh for well over a year. That's a 5L kit. I have high hopes that the same strategy will work well for me with a 2.5L kit.

koraks · 2025-08-10T04:33:19-0400

dcy said:
It sounds like you're saying that CD4 lasts longer in solution than by itself. That can't be right.

In the mixed developer, the hydroxylamine sulfate antioxidant is combined in the mix. Together with preventing any fresh oxygen supply to the developer, this keeps the developer from oxidizing. In the concentrate, the antioxidant cannot be mixed with the CD4 for reasons of chemical compatibility. The main protection mechanism for the CD4-containing concentrate is a sealed bottle, and maybe a little bicarbonate. The moment you open that bottle, things get sketchy.

dcy said:
The reason they're split up in the first place is that some of the other ingredients react with CD4.

I suspect logistics have something to do with this as well.

Btw, factory-sealed concentrates of CD4 (Kodak or Fuji) spoil over time as well. They don't live forever.

dcy said:
That's a 5L kit.

I use minilab chemistry; one batch for me is 12.5L working strength developer. My strategy should work for your smaller batch size however.

You know what they say about assumptions.

halfaman · 2025-08-10T04:49:38-0400

dcy said:
Wait... Something doesn't make sense here. You said that making the 2.5L and decanting it into smaller bottles keeps ages, but you also said that CD4 by itself doesn't week well even if you decant it...

It sounds like you're saying that CD4 lasts longer in solution than by itself. That can't be right. The reason they're split up in the first place is that some of the other ingredients react with CD4.

Have I misunderstood something?

Mixed working solution includes an antioxidant (hydroxylamine sulfate in part B) that the CD4 concentrate missed, like koraks said. For preservation, CD4 concentrate is kept in acidic solution and sometimes with some content of organic solvents with low oxygen solubility.

I prefer to mix the working solution and keep it in brown glass bottles of convenient volume fill to the top. I use as little as 250 ml and as much as 1 liter per batch on a Jobo roraty processor, so dividing CD4 concentrate can be complicated.

I finished last week the last bits of a 10 liters batch of C-41 developer stored that way and mixed three years ago and it was perfect from beggining to the end. Keep in mind that oxidation changes the initial pale yellow color of the developer working solution to dark brown, like in most BW developers, so you can track how well is your storage performing. Same thing for CD4 concentrate, ending with a deep black color when it is completely dead.

dcy · 2025-08-10T05:50:51-0400

Thanks!

I guess that explains why it's OK for Bellini to sell the developer as a pre-mixed concentrate. Now I'm wondering why doesn't everyone give you the developer as a pre-mixed concentrate. Especially the kits that are intended for home users doing small batches.

koraks · 2025-08-10T06:31:55-0400

Like I said, logistics. Bigger, heavier box. More shelf space, higher transportation costs.

MattKing · 2025-08-10T16:30:18-0400

dcy said:
Thanks!

I guess that explains why it's OK for Bellini to sell the developer as a pre-mixed concentrate. Now I'm wondering why doesn't everyone give you the developer as a pre-mixed concentrate. Especially the kits that are intended for home users doing small batches.

It also might be that you need the water as well in order for the mixture to have any longevity. Water is, of course, a chemical too.
And packaging, shipping and storing water costs money.

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