Hacking Film Processing With Coffee

Years ago, doing your own darkroom work was the only way to really control what your pictures looked like. In those days, coffee was what kept you going while you mixed another batch of noxious chemicals in the dark and fumbled to load a tank reel by feel. But did you know that you can process black and white film with coffee? Not just coffee, of course. [Andrew Shepherd] takes us through the process using what is coyly known as Caffenol-C.

Apparently, the process is not original, but if you’ve ever wanted to do some film developing and don’t want exotic and dangerous chemicals, it might be just the ticket. The ingredients are simple: instant coffee, washing soda, water and –optionally — vitamin C powder. If nothing else, all of this is safe to pour down your drain, something you probably aren’t supposed to do with conventional developers that contain things like formaldehyde and methyl chloroform.

Once you start looking, you’ll find that people have also used beer or wine to replace the coffee. Apparently, some recipes work better than others with specific types of film. You still have to stop the developing process, so it looks like the process uses traditional fixer.

In addition to instructions and tips, [Andrews] also shows quite a few photos developed with his coffee solution. Not bad! We don’t really understand the chemistry behind it, but we are sure someone will explain it in the comments.

We actually heard about this process a decade ago. After you have film, of course, you are going to want prints.

31 thoughts on “Hacking Film Processing With Coffee

  1. Pure FUD. I don’t know of any modern film developers that contain either formaldehyde or methyl chloroform. I don’t know of any developer ever that contained chloroform. Some old recipes for lithographic developers contained paraformaldehyde, and some toners as well, but these were uncommon and not really used by your typical home photographer / darkroom enthusiast. I don’t know what use chloroform would have in any darkroom – perhaps as a cleaning agent, but it is a solvent for many plastics so I have doubts about it. I certainly have never encountered it in any of my own experience or in the literature.

    1. The linked page mentions formaldehyde and methyl chloroform but not any of the more typical chemicals used for developer (phenidone, hydroquinone). I’m not sure how commonly formaldehyde is used in modern developers. The common developers have been developed over many years of experimentation to produce superior results. Some use vitamin-c already.

      I can’t see what use methyl chloroform would be in a developer. Developer solutions are aqueous and methyl chloroform isn’t really water soluble. As you say, maybe used as a cleaner for film, to wash things like grease or fingerprints off, but perhaps not in the developer itself (which is claimed to be replaced by this mixture).

      If anybody is going to use this mixture, I’d suggest filtering it before using. Seems like there are a lot of flecks in the images maybe caused by undissolved particles.

    2. I’m not sure there IS such a thing as a modern film developer. But in any case, I’ve done Kodak Process E-4 transparency processing, and one of the last steps, Stabilizer, I think, DID contain formaldehyde. And since a number of E-4 steps were identical to those in the C-22 and C-41 color negative processes, those probably also used formaldehyde. But as you say, no “developer” step contained anything like this, but I think by “developer” he may have meant “film processing chemical”. It’s the process as a whole that matters.

      1. Formaldehyde was pretty much entirely phased out of C-41 in the mid-90s, it uses hexamine or trioxane now… E6 per KODAK does still use formaldehyde, in the stabilizer, NOT developer. And most of the home job E6 kits you can buy don’t include it anymore. Most photographers now and historically never developed color negative or reversal at home, mainly B&W stuff.

        If the author meant in any film processing chemical then that’s an entirely different story than one about Caffenol which just covers the film developer and skips entirely the stop and barely mentions the fixer in passing. Words are important, use the right ones.

        E-4 process was quite awful btw, but not because of formaldehyde – it used some boron compound in the reversal agent that was FAR more toxic and dangerous.

        1. I figured the info must come from a color processes. As far as I can recall all the usual B&W chemicals are safe to handle and put down the drain. Some people and labs saved used developer (or fixer?) to recover silver. Toners and reversal processes were not as nice IIRC and nobody I ever knew used them.

          Anything with formaldehyde of chloroform has been labeled a carcinogen for a long time.

          1. Nope, BW chemicals are not safe and shouldn’t be « put down the drain ».
            It’s forbiden in France, and I think all around europe since about 20 years.
            The only safe product is stop bath, acetic acid (vinegar).
            Of course, color is much worse 8-[, the developper of the Cibachrome process was so acid (Ph close to 1 !) that you had to mix it with a strong alcali before put down the drain, othewise you’d have to change plumbing quite often ;0).
            It’s the used fixer that’s full of silver.
            In the school where I work, the photographic lab has a special drain circuit going to a big cuve since 1998 so it can be pumped and treated by a specialist, and yes, they recover the silver (we could, should do it).
            Photography as allways been toxic, the developper for daguerréotypes was mercury vapor !

    3. Went here to say just that. Black & white developers that caffenol is meant to replace are based on metol and hydroquinone (or para-aminophenol for rodinal), none of which is nearly as dangerous as formaldehyde.
      For more information on what’s in B/W developers read here, you can even make a conventional developer at home if you want:

      On the other hand, if you like rodinal and want to try a homebrew version like the caffenol in the article, there’s parodinal based on paracetamol, which for some reason doesn’t get that much attention as caffenol

      Haven’t tried it though.

    4. The Anscochrome process used formaldehyde in the final step, a stabilizer rinse. The purpose was to stabilize the dyes, although I guess it also served to harden the emulsion.

  2. It would be interesting to know how people are printing developing and etching their PCBs now.

    I used to use Ferric Chloride as an enchant but now because of terrorism I can’t buy it anymore as it’s declared a dangerous chemical that could be used to make explosives. Ironically I can buy all that is needed to make the explosives that most terrorist choose from my local hardware store.

    1. The “developer” used for presensitized PCBs is just sodium hydroxide, and all it does is help to dissolve the emulsion that hasn’t been hardened by light. Not really a developer, since this isn’t a silver-based process.

    2. I tried using vinegar, hydrogen peroxide, and pinch of salt
      A quick web search says that hydrogen peroxide breaks down acetic acid and produces peroxyacid which disolves the copper.
      vinegar / acetic acid (5%) CH3COOH(aq)
      hydrogen peroxide (3%) H2O2(aq)
      salt NaCl(s)
      copper Cu(s)

      The added salt would probably end up producing Copper(II) chloride (CuCl2).

      I remember that it was a bit slow, I probably should have heated it a bit.

      1. I once used saturated salt in vinegar to de-oxidize a large multi strand copper cable about 55mm2 and then water and bicarbonate of soda to neutralize it prior to re-crimping and that worked well. Kitchen chemistry lol, but it worked. It was a high current battery terminal for a large battery.

    3. Ferric chloride should still be available, but I use copper chloride because it can be regenerated and is easy to dispose by precipitating basic copper chloride with sodium bicarbonate, which is a non water soluble copper salt so it does not leech copper into the environment. NurdRage has a video on it.

    1. Helped a student last month with developing a Kodachrome K40 super 8 he’d shot, and Kodak have stopped the K 14 process since 2010, so we’ve developed it 1 hour in 1/100 Paranol, witch is Tetenal’s name for the oldest developper around, the 1891 Rodinal ;0P

      Had to use C 41 color Blix to remove the yellow silver cast, well diluted otherwise it would eat also the images, and finaly used diluted borax on a soft cloth to wash the remaining carbon coating, he was very happy with his plate of 15 meter long spaghetti B & W negative, but it wasn’t convenient to handle because usually the longest film we develop is 35 mm photographic film, that’s only 1,5 meters long ;0).

  3. Tried Caffeinol myself for the first time recently — I’m reviving an old large-format camera so processing the film myself is the way to go — and it definitely does work. While one can quibble about the exact contents of common commercial developer, I believe there is consensus that Caffeinol is still a less toxic alternative, and mixing it yourself has all the DIY appeal of anything else here on Hackaday: pride in getting it right, and opportunity to take risks and experiment in ways that off-the-shelf doesn’t permit. There’s still something magical about simple chemistry with household materials yielding unexpectedly pretty results. And it helps keep costs down, which is something digital photographers don’t have to worry about.

    For making prints without a darkroom setup, scanning/capturing the negatives and inverting them in image processing software is the cheap and flexible solution. A digital camera, even a phone camera, has higher resolution than most flatbed scanners, and there are several good solutions for illuminating the neg to perform that capture. Good compromise between the film and digital imaging worlds.

    1. Maybe the most expensive bit of equipment for making prints is the enlarger. You can usually make a pretty decent enlarger by using the camera in reverse. Just need some kind of clamp to hold the camera vertically above the paper and put the negative where the film went in the first place. Put a light with a switch above it (probably in some kind of box to prevent reflected light hitting the paper) and you have an enlarger. LED lights are probably good as they won’t get really hot. Just need to block out light from outside (or do the work at night). Red safe-lights are cheap but you probably just use a few red LEDs?

  4. I played around with Caffenol a bunch back around 15 years ago, when it was also popular. It’s a fun idea, but IMO not terribly practical or consistent enough for routine use.

    The substance that provides the developer action in Caffenol is caffeic acid (https://en.wikipedia.org/wiki/Caffeic_acid) — a catechol derivative (catechols are known to be capable of reducing silver and are used in “controlled” formulations for other types of developer). Caffeic acid is found in a bunch of other plant-based materials, and catechols and the chemically related tannins are also found in wine.

    There’s no methylchloroform in any B&W developer I’ve ever heard of. Formalin used to be used in hardening baths, but no films made in the last 60-70 years have needed that step (the emulsion hardening happens during manufacture).

    1. “Cons:

      Caffenol is restricted to B&W film. You could use it on color negative stock, but you would end up with a sepia tone across all your negatives.”

      From the linked article, is this from the colouring from the coffee? If so why not use something else with more caffeic acid, like, mentioned in your wikipedia link like thyme or argan oil?

      1. Color negative films require a “coupling developer”, which links the developing silver to color dyes. Color slide films use a non-coupling developer for the first developer and a coupling developer for the second developer.

  5. Did you say argan oil ?
    Scuttles off to see if I have any left, that is likely years out of date but likely fine for this application.

    Re. the peroxide restrictions, a trivially simple approach is to use an HV generator or at a pinch
    a UV-C lamp and cold cathode driver + heater driver to make your peroxide, in solution by bubbling ozone
    through triple DI water with a fish tank positive pressure bubbler to make it all run.
    Certainly works well.
    You don’t get much concentration but this is ironically a good thing as for PCB making 30 vol is just fine.
    Without all the obnoxious additives in pharmacy grade peroxide it works extremely well and will etch a board moderately fast using white vinegar without messing up the UV reactive coating.
    I have no time for anyone who claims that home chemistry is just for b0mb makers and druggies on principle,
    when in fact if anyone really wanted to do harm this would be about the least efficient method if it worked at all.
    In fact its possible to make multilayer boards by electroplating onto a track, adding a layer of UV cure adhesive ie Bondic and then a layer of carbon powder etc, plate over that and repeat.
    Won’t be as effective as a proper board but adequate for hobbyist level use.
    Now where did I put my 155c fine soldering alloy with the copper nanoparticles added?

  6. Not in developer, no. Formaldehyde *is* present in the final stage of reversal film processing. It’s in the “preservative” bath, right after rinsing. It’s very weak, but it’s there – or it was when I was developing film in the 80s and 90s. It’s purpose is to prevent decomposition of the emulsion (gelatin), decomposition of the dyes, and prevent the formation of fungus.

  7. When I studied photography, our film chemistry teacher helped to de-mystify the process by showing us a roll of B&W film developed in orange juice.

    He loaded a camera, took photos of a few of us, then processed the film in class and we were able to view the negatives by the end of the lesson. They were foggy, but recognisable images of us. I loved film chemistry, but I’ve had enough of film chemicals.

  8. Is this person having a joke at reader’s expense? Sure, if you like messing round with films, go for it, but don’t expect to get even half decent photos. If you want to do photography not darkroom dabling, use conventional film, paper and chemicals and forget this time-wasting nonsense.

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