A few months ago, before the COVID-19 pandemic dug its claws fully into the United States, I finally decided it was time to open-up the box of CineStill C-41 chemistry that had been sitting on a shelf since December, and set about processing the pile of color negative film that had been accumulating up to now. I have to confess: I’d been dragging my feet, fearful of this moment — worried whether I’d end-up simply ruining some film and losing shots I’d worked so hard to capture. As it turns out, the worries were unnecessary.
To hedge my bets, I decided not to process any of the “real” rolls of film that were sitting in a pile. Instead, I took a cheap roll of Lomography Color Negative 400, loaded it into my Mamiya RB67, and spent an afternoon snapping-off its 10 6×7 images. I didn’t work very hard at choosing subjects; I didn’t waste the shots, but I didn’t exactly invest in them either.
I’d already previously figured-out how I’d be doing this, physically speaking:
- Water Bath Container
To contain a temperature-controlled water bath for the chemistry (since it all needs to be held at 102°F) I’d chosen a tub from IKEA, the so-called “Pluggis.” I also got a couple of plastic organizers from The Container Store to set inside, which allowed the bottles to be held in-place in an organized fashion. - Temperature Control
I already owned an Anova Precision Cooker (immersion circulator), and wanted to upgrade for the kitchen to the newest model — leaving the older one available for darkroom use. - Chemistry Bottles
Walmart stores in the US carry a range of store brand 1 liter flavored soda waters called “Clear American” whose labels are easy to remove, with a few little spots of adhesive that can cleanly be removed with a touch of Goo Gone — an easily sourced adhesive solvent. I’ve been using them for black and white processing, and just consumed more of them so I’d have the bottles to reuse for 1 liter (1 quart) color chemistry kits too. The bottles are made of PET, have tight-fitting caps, and are reasonably heavy gauge, and they’ve been perfect for my darkroom use.
All that was truly needed to begin was simply to mix the chemistry into the 1 liter bottles, set-up the water bath, get everything up to temp, and follow the directions.
Here’s what everything looked like when set-up:
Chemistry Mixing
While I purchased a CineStill liquid C-41 kit, in reality, the kit and its contents are identical to other liquid 1 quart / 1 liter kits from other sources. CineStill also sells a powdered version of the kit. But the CineStill branded kits appear to be identical to the ones sold under the Film Photography Project (FPP), Freestyle / Arista EDU, and Unicolor names, among others. The truth is that I don’t know, but it would appear that all of these kits are actually made by Unicolor. But whoever makes them, the instruction sheets are virtually identical in design and layout — only the branding is changed, and of course the mixing instructions when it comes to the liquid kits vs. the powdered.
Indeed, mixing the chemistry is easy, and the instructions give you the precise measurements needed, along with what to do, and in what order to do it. When it’s done, you have a 1 liter bottle for each of developer, blix (bleach/fix), and stabilizer/rinse. Powdered kits are not entirely different, other than the stabilizer/rinse being omitted in some brands (CineStill omits it; FPP does not); modern film stocks apparently don’t need the stabilizer, and the one in the liquid kit is as much a surfactant (rinse aid) as a stabilizer. If you have hard water (as I do) and will need a surfactant (as I do) to prevent water spots, Kodak Photo-Flo can of course be used — and in fact, I use it even if there is as stabilizer/rinse in the kit.
Using the Kit
One of the best things about C-41 processing is that you don’t have to worry about adjusting things for this brand, or that box speed, etc. — if the roll is marked C-41, it follows the same process. (You do need to adjust times as you process rolls, but that’s covered in the next section.)
With your chemistry up to temperature (again, 102°F or 39°C), you can do a one minute pre-soak if you wish, and I like to do this (I actually do a pre-wash not a pre-soak to remove any anti-halation dyes and avoid polluting my developer). The water needs to be at same temperature as everything else.
Afterward, you develop, starting at about 3 minutes 30 seconds, and growing as you process more, per the chart I’ll share below. Agitation is basically four inversions every 30 seconds — twice as often as my black and white method, using Paterson tanks in both cases. Pour that back in the bottle.
Next is blix (bleach/fix), which is a consistent 8 minutes. The instructions say it can be in a much wider temperature range, but I see no reason to vary it, especially if you’re using an immersion circulator — so everything’s in the water bath at the same temp for all steps. Pour the blix back in the bottle.
Give the film a good wash — again, same temp.
This is the point where I vary from the directions. While I use the stabilizer/rinse step if the kit provides one (see the info above), afterward, I do the standard water-saving “Ilford method” wash the same way I do with black and white processing, followed by a standard Kodak Photo-Flo rinse as per the directions. Only then do I pull the film and hang it to dry.
Without this last step, I was getting a lot of residue on the film after drying, and while it wiped off somewhat easily with a microfiber cloth, the residues were gone if I did a better rinse, followed by Photo-Flo. That said, I have very hard water here, which I’m sure caused or contributed to the issues.
I do not intentionally push or pull color films, but if you do, the instructions have time corrections. Just note that they’re for the base times, and it could get a little tricky to “double adjust” for push/pull and extending the kit. Speaking of, let’s dig into that.
Extending the Kit
The 1 liter C-41 kits are all rated as providing sufficient “power” to process just eight rolls of 120 film. FPP and many other sources talk about the fact that these kits actually have the capacity to do far more than that, and given the cost of each kit, doing so was a virtual necessity in order for the economics to make real sense over lab processing.
The CineStill kit I purchased locally from Denver Pro Photo (see my Vendor Directory) in March 2020 sells for US$36.00. The same kits can be purchased online from Freestyle for US$26.00 (when they have them in-stock anyway). At the local price point, that ends-up being US$4.50 per roll if you process just eight rolls, and that’s no savings at all over the lab I normally use to do a roll of film. If I’d gotten them from Freestyle, it’s better (US$3.25 per roll), but still not a huge savings. Thus, for this to make sense, extending the kit was essential.
If you intend to keep to the suggested limits, then just follow the directions, and process all eight rolls of 120 (or whatever combination you’re processing, as per the printed instructions), and use the same processing times for all of them. It’ll work-out just fine. But if, like me, you really need to get the most out of it, you’ll need to accommodate that.
I first read about this on 120studio.com in this article. And then I found an interesting cheat sheet and further discussion in this blog post. In the end, I simply used the 120studio.com formula to extend my times, beginning with the second roll processed (not the ninth roll, as in the cheat sheet I referenced). I rounded up or down to the nearest 5 seconds, and ended-up with this:
While the 120studio.com article based the formula on a projected capacity of 40 rolls of 120, I knew I wouldn’t try to stretch my kit anywhere near that far. I rather arbitrarily chose 20 rolls, and didn’t think I’d try to get even that much out of it. In any case, I had my times planned out, I’d keep careful notes on performance and outcomes, and proceeded to dive right in.
It’s worth noting that the developer is the only chemical I extended times with. The blix and stabilizer were used at the published times.
How it Worked
I could drag this story out, but I’ll cut to the chase: The first roll worked out perfectly, and the shots I knocked-out in an afternoon were some of my images so far this calendar year. (Lesson: Don’t overthink your shots, because clearly some of the best come from just letting go.)
And while the first roll worked out perfectly, so did the second. And the third. And the fourth. And the fifth.
In fact, every roll worked perfectly. The 15th and 16th rolls started to concern me; they seemed unduly dark. It turned out to be the photographic subject matter and film stock, because when the 17th roll came around (a different film stock), it might as well have been the first roll in terms of appearance. (The two rolls that concerned me scanned fine and were not defective in any way.)
Finally, I did one more roll for a total of 18 rolls of film total, mostly 120, but with a couple of 135 rolls in there as well. All the rolls used the increasing times I showed above, based on the 120studio.com calculation.
I stopped at 18 rolls for two reasons:
- I was out of color negative film that needed to be processed.
- The developer and blix were both starting to get quite dark (the blix in particular), and they had started to have a very, very strong and somewhat offensive odor (again, the blix in particular). Considering I’d gotten the unit price down to US$2.00 per roll, I figured I’d gotten it all to be very economical, and had “gotten my good out of it” as they say.
Honestly, it seems obvious that I could easily have gotten to 20 rolls, and probably more. In practice, I think I’ll continue to remain a bit conservative.
The Unanswered Question
The one item I’ve not answered just yet is how long the chemicals can sit in between rolls and still be effective, and whether that changes the adjustment times in the table above. Obviously oxygen in the bottles of the mixed chemicals does have an impact on them over time, although nothing I’ve seen has yet attempted to quantify it. I’m also not particularly interested in potentially losing images by testing those limits. The longest I let the chemicals sit between rolls was three days. All 18 rolls were processed over the course of 2-1/2 weeks in total — not much time for the mixed chemistry to oxidize from sitting on a shelf, really.
When I seal my bottles, I try to expel as much air as possible from them. You can do that by squeezing the bottle to get the liquid as near the top as possible, or you could — as I did — use “canned air.” It’s not actually air; in most cases it’s 1,1-Difluoroethane, or DFE, a refrigerant also known as R152a. I insert the end of the straw of the can into the top of the bottle, release a good measure of the propellant with the cap ready to place on top, then quickly do so and secure it. Because DFE is heavier than oxygen — it has a weight of 66 g/mol, vs. oxygen’s weight of 16 g/mol — so a layer of it should form against the mixed chemistry, and block the liquid from the oxidative effects of the oxygen in whatever actual air in still inside the void in the bottle.
Argon (with a weight of 40 g/mol) is quite frequently used for the same type of thing in applications like wine preservation. But aerosol argon gas is fairly expensive. DFE should be an adequate substitute for the darkroom, but my only concern is its possible chemical reactivity with the various processing chemicals. It appears to do the job with my black and white chemicals for weeks and weeks at a time, and I’ve found that it can keep mixed paper developer — the Ilford Multigrade developer I use is rated to remain viable for just one day at the dilution I use — in usable shape for at least two weeks (the longest I’ve tried it as I write this article). As I continue to process C-41 at home, I’ll continue doing this, and will monitor if, how, and when the chemicals seem to deteriorate and start producing unacceptable results.
Problems and Pitfalls
It seems obligatory to have this section in this article, but I have to be honest: I didn’t run into any problems, nor did I run into any pitfalls. C-41 is exceptionally easy, and I’m not sure why I avoided trying it for so long.
That being said, there are a few things to know:
- Temperature Control
Don’t think you’re going to get away with doing this poorly. You won’t. The developer step, at a very minimum, needs to be precise, or you’re essentially doing push or pull development when you don’t want to. An immersion circulator (“sous vide machine”) may well be optional, but if you want this to be even remotely simple, repeatable, and consistent, you’ll need one. Bonus? You can use it with black and white as well, and end-up with a much more consistent, more repeatable end result with that too. CineStill and FPP both sells immersion circulators for darkroom use, and the CineStill solution has some nifty photography-specific features. In truth, you need nothing darkroom-specific; the Anova Precision Cooker or any other “stick type” immersion circulator can be used provided is can be adjusted to the applicable temperatures. Monoprice has one in their Strata Home line for $70, which is the same price that FPP sells theirs for (when they have them in-stock) at the time I’m writing this article. - Everything Else is the Same
The other stuff that can go wrong with home film processing generally can go wrong here as well: improperly mixing the chemistry, using exhausted chemicals, using the wrong chemicals in the wrong order, not following the directions, improperly loading film, using poor technique, being over-aggressive or over-gentle with agitation, exposing the film to some light when loading on the reel, etc., etc., etc. The solutions are the same too: Follow directions carefully, know what to do and how to do it before you even start, and generally just pay attention and focus on the task at hand. - Rinsing
If you have hard water, consider my altered end steps above to prevent residues and spotting.
And truly, that’s about it. If you do black and white at home now, but haven’t tackled C-41 color negative processing, give it a try. Chances are, like me, you’ll wonder why you waited.
Happy processing!
