Questions regarding Cinestill CS41 kit

I develop B&W film myself but have been sending my color film to the lab. I'm now considering the simplified CS41 kit from Cinestill, which is a 2-bath kit. Even if I only did 3 rolls with it I'd still save money over the lab, but I have some concerns about its temperature sensitivity. I don't have a way to control temperature at the moment but I do of course have a thermometer. I figure I'd use a hot water bath or something to keep the tank warm and start my chemistry off at the right temperature and hope that it doesn't cool down too much during developing.

I know this could cause color shifts but I'd like to know, how much? Let's say I use this chemistry kit, and I have a water bath at about the correct temp with my tank and chemistry in bottles in the tank. I'd control the temperature by adding hot tap water to the bath until it's at temp or slightly above, and then I'd just go ahead and process the film. I assume it might cool down a small amount during the process, but would this cooling be enough to ruin the negatives? Or would it cause minor color shifts which I may be able to live with, or maybe even cause practically no issues at all?

The next thing I'm concerned about is the shelf life. I read somewhere that Cinestill says it'll last for 2 months at most once mixed, is this true? And is there any way to extend this? I have seen people here talk about sealed bags for chemistry that can make, for example, xtol last a long time, but I don't understand if this would help a C41 blix, since to my knowledge the bleach and fix degrade one another and so maybe sealing it off from outside air wouldn't even help the longevity.

Another question I have about the longevity is if I can potentially mix up a smaller portion of powder instead of the entire kit. I understand that this would run the risk of different sized grains of powder in each batch causing chemistry changes but I'm curious if anyone has tried this before with the cinestill kit or with other chemistry and if it's doable, because if I could mix up a fractional batch then I wouldn't worry too much about the shelf life.

If anyone has any answers I would appreciate it.

Minolta93 said:

Or would it cause minor color shifts which I may be able to live with, or maybe even cause practically no issues at all?

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Especially if you scan your film instead of printing it optically in the darkroom, your approach will work fine.
If you optically print, there may be slight color problems but unless you do side-by-side comparisons with properly developed film, you may not ever notice it.

Sure, it's best to do it the 'right' way. But the method you propose will work OK for amateur use (I don't mean that in a derogatory way).

Minolta93 said:

The next thing I'm concerned about is the shelf life. I read somewhere that Cinestill says it'll last for 2 months at most once mixed, is this true?

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Can't say. The general advice of limiting contact of the chemistry with oxygen applies. I don't think there's a definitive answer here.
Btw, some BLIXes keep very well; e.g. Fuji RA4 blix is incredibly stable - but will ultimately also break down. If the Cinestill stuff is just as good, really depends on how they formulated it. I don't expect they have the same kind of competence in this area that Fuji and Kodak have/used to have.

Minolta93 said:

if I can potentially mix up a smaller portion of powder instead of the entire kit.

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Especially with a color developer I just wouldn't risk it. I know about the lengthy discussions about this topic relating to B&W developers. The thing with color is that it's all just a little more finicky, especially the developer. With some additives the concentration is really low and if you end up with a slightly skewed balance, the actual mixed chemistry may be pretty far off-kilter.

I'm all for cutting corners, but be wary of stacking one guess on top of another. There's a lot we can get away with, but compound errors are difficult to solve.

koraks said:

Especially if you scan your film instead of printing it optically in the darkroom, your approach will work fine.

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I do. One day I'll do B&W and then RA4 printing, hopefully, but not at the moment.

koraks said:

Sure, it's best to do it the 'right' way. But the method you propose will work OK for amateur use (I don't mean that in a derogatory way).

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That's what I'm going for. I'm on a student budget at the moment, so I'm fine with compromises.

koraks said:

I'm all for cutting corners, but be wary of stacking one guess on top of another. There's a lot we can get away with, but compound errors are difficult to solve.

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I see. If a component is important but makes a small percentage then I could very well have the mixture include a totally wrong proportion of it. I wonder if the liquid CS41 kit sold by Cinestill might be a viable choice for mixing up smaller batches of chemistry because it would avoid this problem. If I had a bit more money to spare I wouldn't mind experimenting.

Minolta93 said:

I wonder if the liquid CS41 kit sold by Cinestill might be a viable choice for mixing up smaller batches of chemistry because it would avoid this problem.

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It should be easier to measure out fractional parts, but in return you get the challenge of keeping the remaining concentrate from going bad.

I'm sorry about the lack of clear-cut, definitive answers; I'm afraid there aren't any!

Perhaps if monetary efficiency is very important, the best you could do is save up your C41 work and then do it all in one go (within a few days) so you are certain to use the chemistry without it deteriorating over time.

Btw, I'm always a bit weary of reusing an already-mixed and used color developer without replenishing it. Halides tend to build accumulate in the developer and these work as a restrainer and influence acutance. Perhaps there's no visible effect when processing 2-3 films in the same liter of developer, but is that also true once you get to the 6th film? Or the 10th? There will be drift, but the question is how bad it'll be.

Temperature control is really critical, so I world definitely invest in a $50-100 sous vide heater. Considering the costs of color chemicals, color film and our time, this is not that big of an investment. Besides you can use it to cook food.

I learned a trick of longevity from my buddy Jan. There are aluminum lined pouches / wine flasks (500ml) that can be light proof and air right (you squeeze out any last bit of air). I premix 1L of working solution, and store each chemical in two flasks. So far, c41 and e6 chemicals can easily last 6 month, is not longer. But I usually finish one 16 roll kit within 6 months.

And if you use Flic C41 kit or similar, they have separate bleach and fixer. I wash between each steps, so the chemicals won't contaminate each other. That might help with longevity as well.

If your budget is really tight, you only need to worry about accurate temperature for the color developer and nothing else. Then a large water bath in a foam cooler, plus pre warming your film and tank, should be doable.

Unlike e6, you cannot really see the true color by inspecting the C41 negatives. Thus by shooting last frame with a color target or neutral grey card, you can always compensate by color correction in digital.

I would say don’t over think it. Decades ago I used the picnic cooler water bath method and processed many rolls of C41 and E6 without difficulty. Just get everything (tank, chems, etc) up to temp and settled and you’ll be fine. I was printing RA4 and Ciba, everything was fine.
I would mix all the chemistry up at once and store it in glass or PET bottles or a wine bag, making sure all oxygen is expelled. It should last a very long time. If you question it, you can always shoot a few frames and process a clip test without risking a whole roll.
I always try to shoot a gray card and often a color chart in a frame, it makes color correction much much easier once you get into post.
Have fun!

head down to target or walmart and get a cheap slow cooker that has a warm setting, keeps the chems around 102 which is great! if you want to get the best results, dont go the blix route, use separate bleach and fix. kodak flexicolor chems are cheap, but shipping is brutal. freestyle or unique has them.

if your interested, I have some flexicolor bleach you can have. I can give you a liter or so to try out. It lasts a long time if you re-oxygenate it. fixer and developer are easy and cheap to ship.

I use wine bags and squeeze all the air out. I have gone 18+ months on mixed developer with the and have not noticed any color issues with both c41 and e-6. well worth the $4 per bag cost

john

Minolta93 said:

I develop B&W film myself but have been sending my color film to the lab. I'm now considering the simplified CS41 kit from Cinestill, which is a 2-bath kit. Even if I only did 3 rolls with it I'd still save money over the lab, but I have some concerns about its temperature sensitivity. I don't have a way to control temperature at the moment but I do of course have a thermometer. I figure I'd use a hot water bath or something to keep the tank warm and start my chemistry off at the right temperature and hope that it doesn't cool down too much during developing.

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If you're filling the entire tank with chemicals, you do not need a water bath for temperature control. You can test it yourself: preheat the water to 102F, then submerge the tank into it for a minute (this will pre-heat the tank). Then pour the water out, and replace it with the simulated developer (also water) heated to 102F, continuously agitate for 3:15 and measure the temperature inside the tank after that. You will see it drop by just 1.5-2F depending on your ambient.

The water bath is useful for rotary agitation when the volume of chemicals is small so they're more susceptible to a temperature drop.

blee1996 said:

Temperature control is really critical, so I world definitely invest in a $50-100 sous vide heater. Considering the costs of color chemicals, color film and our time, this is not that big of an investment. Besides you can use it to cook food.

I learned a trick of longevity from my buddy Jan. There are aluminum lined pouches / wine flasks (500ml) that can be light proof and air right (you squeeze out any last bit of air). I premix 1L of working solution, and store each chemical in two flasks. So far, c41 and e6 chemicals can easily last 6 month, is not longer. But I usually finish one 16 roll kit within 6 months.

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The heaters are great, fast and accurate.
I have a Digibase kit that comes in 500ml pouches and still going strong after 6mths.

Also if you happen to find a Jobo CPE or similar going cheap, grab it. I have the original that works great both for colour and b&w, paid about $30 for mine, latter models go for a lot more.

koraks said:

I'm sorry about the lack of clear-cut, definitive answers; I'm afraid there aren't any!

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Oh, I didn't expect any anyway, just general advice. Batching exposed film is definitely something to consider and something I already do to save on shipping costs because I normally use a lab that processes by mail.

blee1996 said:

Temperature control is really critical, so I world definitely invest in a $50-100 sous vide heater. Considering the costs of color chemicals, color film and our time, this is not that big of an investment. Besides you can use it to cook food.

I learned a trick of longevity from my buddy Jan. There are aluminum lined pouches / wine flasks (500ml) that can be light proof and air right (you squeeze out any last bit of air). I premix 1L of working solution, and store each chemical in two flasks. So far, c41 and e6 chemicals can easily last 6 month, is not longer. But I usually finish one 16 roll kit within 6 months.

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I would definitely get the sous vide at some point since I plan to put more time, money, and effort into this later on anyway. As for the pouches, I have seen some of those and I was considering them for b&w chemistry as well. Have you stored blix in any of them and if so do you know how long it might last?

blee1996 said:

And if you use Flic C41 kit or similar, they have separate bleach and fixer. I wash between each steps, so the chemicals won't contaminate each other. That might help with longevity as well.

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In your experience how long do the separate bleach and fixer last?

blee1996 said:

If your budget is really tight, you only need to worry about accurate temperature for the color developer and nothing else. Then a large water bath in a foam cooler, plus pre warming your film and tank, should be doable.

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My long term budget isn't tight but at the moment it sort of is, but I also still want to do it. The foam cooler sounds like a pretty good idea.

blee1996 said:

Unlike e6, you cannot really see the true color by inspecting the C41 negatives. Thus by shooting last frame with a color target or neutral grey card, you can always compensate by color correction in digital.

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I've wanted to get a color checker, actually. Is there any one you recommend?