Introduction: Caffenol-C: Coffee Film Developer

To develop a roll of film and make negatives for printing, it is necessary to strip the film's exposed silver halides. Usually, this is done with conventional developing solutions. Since the developer is the primary ingredient in the process, a lot of it is used. Unfortunately, the developer is one of the most problematic chemicals used in photography. It's awful for the environment, and it can be expensive. It smells pretty nasty, too. (Fixer, a chemical used later in the process to preserve the negatives, has similar issues, but it won't be covered in this article.) Developing solutions are even worse after they've been used. Most of the silver halides from the film are washed away in the developer (some are left over until the stop bath), leaving you with a chemical that you can't just toss in the yard. 

To get rid of used developer, it has to be stored until it can be taken for hazardous waste disposal. Before I learned all this, I was used to tossing my bucket of chemicals into the soil in my backyard. It was pretty close to a storm drain, too. Not all that cool. It would be great to have a developing solution that could be thrown out the window, but even Caffenol won't get us that far (ugh, silver!). Using it as an alternative developer, however, will reduce the nastiness and eye-burning odor a bit. Even better, it's cheap! You don't often see greener options that are cheaper than their nasty counterparts.

Caffenol is a developer consisting of only washing soda (which is used commonly as a laundry detergent), coffee crystals (like Instant Folgers), and sometimes vitamin C (for making Caffenol-C). It replaces the commercial developing chemical in developing black and white film. It was introduced seventeen years ago by Dr. Scott Williams and his class at the Rochester Institute of Technology when he experimented with his class to find a household developer. After reading a bit about Caffenol, I followed the instructions on the Photojojo blog (link below), so the steps here are based off of their methods and tips from some helpful photographers at the printing lab.

Note: Every photograph in this article, with the exception of three stock images, is shot in black-and-white and developed with Caffenol-C.

Helpful links and sources:

Step 1: Collecting and Prepping Supplies


I managed to get all of my supplies from the local hardware store, photography lab, and under my sink. It's not too hard.

From the photo store:
Film, if you don't already have a roll that you want to develop
A daylight developing tank - nothing specific, just don't forget a matching spool!
Changing bag or a dark room
Fixer - I use Kodak Professional
Optional: Brown chemical storage jug (or two)

From the hardware store: 
Washing Soda - I use Arm & Hammer (not baking soda) 
A few measuring cylinders - 16 oz. each
Large glass cups, unless you already have some that you're willing to clean well

You might already have all of these things. They're pretty common, you know.

From under the sink:
Vitamin C powder - You might need to get this at a drugstore or online.
Instant coffee crystals - Well, it's above the sink, but hey.
An eency bit of dishwashing liquid soap
Bottle opener and scissors
A few gallons of water - Get it from the hose, nearby pond, doesn't need to be fancy.
A clothespin or binder clip

Once you're finished with the process, you'll be left with a strip of negatives that will need to be cut and sent to a photo lab for printing, unless you have a negative scanner or you're able to print them yourself.


Fill two glasses with 6 oz. of water each. Mix 5 teaspoons of instant coffee crystals and between 3/4 and 1 whole teaspoon of vitamin C (see step five for more detail) into the first glass. Mix 3-1/2 teaspoons of washing soda into the second glass. Don't leave too many lumps! When everything's mixed, stir the two solutions together in a single glass. Ta-da! It's Caffenol-C!

Follow the instructions on the bag your fixing chemical came in to make a batch. I decided to mix my whole bag at once and keep it in a brown chemical jug under the counter. It should last for a while, and you can reuse fixer a few times.

Fill another clean glass with water and stir in a few drops of dishwashing liquid. It doesn't need to be specific, it'll just be used to wash the fixer and other leftovers off of your film. Don't get too many bubbles, though, since it can be a pain to pull your film out of a bucket of foam.

Step 2: Loading Film and Checking Your Station

Loading Film

If you're using a changing bag, follow the instructions in italics and then move on to the next step.
Open up the changing bag and put the exposed film canister, daylight developing tank, bottle opener, and pair of scissors inside. Be sure to close allof the zippers! Then, roll up your sleeves and stick your arms in the bag. 
Make sure there aren't any light leaks in the changing bag or darkroom. Use the bottle opener to open the canister, and cut the film strip off of its spool. Cut tiny little corners off of one end of the strip. They shouldn't be too big, just about one square millimeter triangles. Wind the strip onto the reel that fits into the tank, winding trimmed-end first. Put the reel back in its tank and close everything up before opening the changing bag and removing the items.


At this point, you'll want to have:
• A loaded developing tank
• Three glasses of mixtures - Caffenol-C, soapy water, and fixer
• A few gallons of water nearby - a hose works well
• A stopwatch
• A rag to keep things nice and dry
• Various chemical containers to hold reusable fixer and Caffenol, and nasty water
• Music (iPod, laptop) since there's a bit of waiting time involved
• A clothespin or binder clip

Step 3: Developing, Stopping, Fixing, and Washing

Hurray! This is the slow and tedious part.


Make sure the developing tank lid is screwed on really, really tight. Then, take the rubber cap off the top. There might be an agitating rod, which you should remove as well. Slowly pour in the Caffenol-C mix. When you've finished off the cup, put the cap and the agitating rod back on the tank and immediately start the stopwatch. Begin agitating (flipping the tank upside down again and again) the tank slowly for one minute. Agitate thrice every minute until the stopwatch reads 12:00. That's one minute agitating nonstop, eleven minutes agitating three times per minute. When it's finished, take off the cap and the agitating rod and dump the soup in a storage bucket. 


Fill the tank with water, and cap it. Agitate six times. Dump this water in the container with the Caffenol-C, or find a new bucket and save the developer for reuse once or twice more. Repeat this step twice more for three rinses in total.


Fill the tank with fixer, and continue to cap and uncap when it makes sense, of course. Reset the stopwatch quickly and start it up again. Agitate thrice each minute for seven minutes. I've heard it's better to go past the set time than under the set time. When finished, dump the fixer into a container. I'd recommend a second container for used fixer, as long as you mark how many times it has been used. 


Fill the tank with water. Agitate thrice. Pour the water out. Fill the tank again with water. Agitate six times. Pour the water out. Fill the tank one last time with water. Agitate twelve times. Pour the water out. Bored yet? 

Pour that glass of soapy water into the tank. It doesn't need to be filled. Agitate slowly twenty-four (24) times. Pour the soapy water out. 


Step 4: Drying and Printing


Unscrew the main lid of the developing tank and take out the spool. It's covered in bubbles and soap. Don't fret. If you're using an oscillating plastic spool/reel, you should be able to slide the disks apart and pull the negative strip right out. If you're using a fixed metal spool/reel, you should be able to unwind the negative strip. 

With your fingers or a squeegee, wipe most of the suds off the strip. You could even go the extra mile towards minimizing streaks and wipe it down gently with a photographic sponge (recommended). Hang the strip up on a shelf or something tall with a clothespin or binder clip and cut the unexposed ends off (optional). 

Leave the film hanging overnight, or twenty-four hours if you want to be absolutely sure it stays straight.


I've never had the pleasure of printing from negatives myself, so you'll have to find another 'able for that. However, there's nothing wrong with getting your negatives scanned at your neighborhood photo store. Asking for prints is fine, too, but you'll sacrifice a bit of quality (though there isn't a whole lot in the first place if you're just starting off with Caffenol). I go to Marin Filmworks in the Bay Area (, and I love them. I received great help researching Caffenol and other alternative development techniques during some visits in the last year. Sorry for the bit of advertising, but I like supporting one of my favorite local businesses. 

Enjoy your beautiful, unique photographs!

Step 5: Extra: the Effects of Vitamin C

When I first heard about Caffenol and Caffenol-C, I read a couple of comments questioning the addition of vitamin C. The responses suggested it reduced fogging and shortened the developing time. I decided to test how varying the amounts of C affected the contrast of final prints if I kept a constant developing time. The experiments weren't the most thorough, but I  managed to get an idea of what the C was doing. 

I exposed six rolls of film with shots of a black-to-white grayscale chart. I developed one without vitamin C (image #1), one with 1/4 teaspoon (image #2), one with 1/2 teaspoon (image #3), one with 3/4 teaspoon (image #4), one with 1 teaspoon (image #5), and one with 5/4 teaspoons (image #6). To measure the contrast of the final scans, I cropped chunks (image #7) from each black section and each white section of the sets, then tried to average the shade and find it's hex. value with It may not have been the most efficient method, but I ended up with a graph (image #8) that made sense.

The trend lines dip inward at the 5/4 mark, which leads me to believe that the vitamin C is affecting the development speed. With more C, the film was over-developing, and losing contrast while getting grainier. With the graph shown below, I was able to see what I'd expect to be a "sweet spot" for developing film with peak contrast. This may not be what one wants, however. Photojojo suggests less C. I think it's still worth experimenting solo to find the best combination of vitamin C and developing time for you.


Smartis (author)2015-06-13

In this instructables, you measure the recipe by Teaspoons.

Is that the standard out-of-the-drawer teaspoon, or that american measuring teaspoon ? ;)

/ Jacob

CrystalB1 (author)2014-11-21

Hi I have a question. Is there anyway this process or anything you can do at home would develop color film? Thanks!

Joe_Iannandrea (author)2014-06-04

I certainly appreciate the effort to promote Caffenol-C here. It, and related Coffee/Vit. C based developers are certainly worth investigating by anyone interesting in processing their own film. I'm afraid, however, that there are some important factual errors here with regards to environmental considerations. I would hate to have readers decide to use Caffenol-C with the thought it will make a significant difference to the environment only to discover that the real benefits are almost non-existent. More importantly, however, the information as it is presented can result in misunderstandings that could lead anyone so concerned away from steps that could make a more substantial difference.

Standard black and white developers, while certainly not good for the environment, are typically no worse than other everyday products virtually everyone uses. We have a tendency to think of anything referred to as a "chemical" as, to use the phrase from the original write up, awful for the environment. If I handed you a beaker and told you it contained 2-Isobutyl-3-methoxypyrazine you might be hesitant to simply pour it down the drain, but this isn't a constituent of any commercial film developer, it's a chemical found in coffee. It seems to be a part of our collective psychology that the word "chemical" is used to denote some sort of "badness". It's easy to forget that water is a chemical, every molecule in your body is a chemical. In the end, any sort of "stuff" we encounter is a chemical.

In this regard Caffenol developers may be somewhat better for the environment. I say may be because photo developers are not, in fact, considered any worse for the environment than many other everyday products. Usually the worst ingredient in a developer is the alkali that almost all of them contain, and one of the stronger ones it the same sodium carbonate used in Caffenol. To be clear I make no such claim here, but if someone more knowledgeable than I were to assess the environmental impact of Caffenol as greater than some commercial film developers I wouldn't be taken aback at the least. All of this though misses a much greater point, which is that with regards to the environmental impact of developing film, the developer is barely worth looking at.

To understand why, here's a quick rundown of what happens when you develop a film. (I'll limit this to black and white film, but the only significant difference with color film is that in the end all of the silver ends up in solution.) At it's mosts basic film is just a clear plastic base coated with an emulsion of silver salt (silver halide) suspended in a gelatin medium. To develop the exposed film it is first immersed in the developer which converts only those silver halide that have been exposed to light into metallic silver. It may then go into a solution designed to halt the developing process but the critical next step is to put it in fixer. Silver halides are soluble in the fixer but metallic silver isn't. The unexposed parts of the film are washed clear therefore, leaving only the exposed parts with a deposit of metallic silver. (The tiny silver particles appear black, unlike the shiny continuous surface of, say, a silver spoon).

It is, therefore, absolutely untrue that most of the silver from the film washes out in the developer. Most commercial developers contain sodium sulfite which, in higher concentrations, can act as a mild silver solvent that reduces the appearance of grain, but the amount of silver that can end up in the developer as a result is negligible compared to what ends up in the fixer. In any case it wouldn't matter as, in the end, the same total amount of silver ends up getting washed away during the process, regardless of which stage this happens at. Commercial photo labs wash most chemicals down the drain as they're considered of little more of an environmental problem than dirty dishwater. Fixer on the other hand goes through a process of silver recovery. This is done both to comply with the environmental regulations that exist pretty much anywhere commercial photo labs do, and because, hey, free silver.

For this reason it's not even possible to come up with an environmentally friendly fixer. Here's something I bet you didn't know - it's possible, following a very specific set of guidelines, to make a fixer with nothing more than water and ordinary table salt. (If you're thinking of trying this, I said veryspecific for a reason. I take no responsibility for any film you ruin if you try to do this.) If you're still not sure why this isn't environmentally friendly, remember what fixer does. Even if you could make it from organically grown native wildflowers, when it's used it still ends up with the same amount of silver in it. If putting exhausted commercial fixers based on ammonium thiosulfate down the drain does 100 units of bad for the environment, salt fixer does 99 units of bad. Knowing how to use salt as fixer is less a comfort for the environmentalist than it is for the zombie apocalypse preparer, knowing they can still get workable negatives when it all goes pear-shaped.

If environmental concerns are your first priority, I urge you to take the time to find a commercial lab that will agree to process your spent fixer for you. Most will be willing to do this; the silver they recover makes it worth their while. This will do orders of magnitude more good than any choice of developer ever could.

Am I saying Caffenol is not worth the bother? Not a bit of it. The blogs and forums where these developers are discussed Caffenol users routinely speak of it in glowing terms, but they're not praising its benefits to the planet compared with commercial formulae.

The truth is, from an image quality standpoint, it's a darn fine developer. Many find it yields higher film speeds without the usual increase in graininess. It's also flexible in that the formula can be adjusted to work better with special situations or unusual films. Just having all the ingredients on hand invites tinkering for those who are so inclined. Lastly, shops that cater to those of us with an interest in good ol' fashioned photography are a dying breed. If you don't live in a major urban area where one can be found obtaining photo chemistry usually involves ordering online, paying extra for shipping then waiting. Now you can buy film chemistry at the grocery store. How cool is that?

kylielouhuygens (author)2014-04-22

How exactly do you get the fixer and where???

wsround (author)2014-01-09

This is very interesting. I have not developed my own film since I was in high school 30 years ago.

About the vitamin C I am not absolutely sure but I think fruit fresh is vitamin C and it is available in the grocery store. I seemed to have read the label some time ago and seem to remember that it is vitamin C or mostly vitamin C.

aidanjarosgrilli (author)2013-06-27

Hi, this is awesome, but I have one question, do the developed negatives fade over time?


The image in negatives developed with Caffenol C is the same metallic silver particles you'd find in a negative developed with commercial developers like D-76, HC-110, etc. As such, it can fade if the fixer isn't completely washed out or if contaminants in the atmosphere convert the silver into something less opaque (silver oxides, sulfides, and halides come to mind) -- but images produced with Caffenol and Caffenol C are no more fugitive than those made with commercial developers. Further, Caffenol (no C) produces a "stain" when developing, darkening the actual gelatin of the emulsion in proportion to the amount of silver developed (called "imagewise stain"), as well as the overall "general stain" of the coffee acting on the gelatin -- and an imagewise stain will generally survive processes (like potassium dichromate and sufuric acid photographic bleach) that will completely remove the silver image (the stain image from Caffenol is faint; there are better developers for this if you want to experiment with grainless stain images).


thanks for the reply


Thanks! I can't actually tell you whether or not they fade, since I've misplaced the negatives that I had developed with this technique. I'm sure their nature depends on the final washes and fixing chemicals used, and on their storage.

woodc1000 (author)2012-09-15

The Starbucks near me gives used coffee grounds out for free for people to put in their garden/compost piles. I've looked online and some people have mentioned using used coffee grounds for developing but i'm not convinced. Has anyone else tried this with any luck?

EgiCz (author)woodc10002012-10-29

Hi, woodc1000,

yes, it works. I tested two weeks ago.

The developing chemical is in coffee directly. It is not any "magic substance" only in instant coffee. It is any chemical similar to hidroquinone (some type of phenol, don't know exactly). This is present in ground coffee as well.

In case of caffenol developer is there second developing chemical: ascorbic acid (vitamin C). Can make pictures less noisy and better in midtones. But hydroquinone can be enough (more contrast, more grain).

Just imagine - what is the instant coffee? Once used coffee :-) Boiled, dryed and again dissolved in water :-)

I tested to take about 10 portions of rests of coffee. Dryed on radiator. Next boiled for 2-3 minutes in 0.6 liter of water. Filtered throught old handkerchief (I got about 0.4 liter back). And cool down to room temperature (20 degrees approx). Added 2 or 3 soup spoons of washing soda during the cooling process.

OK. I take a piece of film. Here is one problem - I had those days free time only during late evening or during night, so this was negative Ilford P4 (a clone of HP5+) 400 ASA, but exposed as 1600 - this is twice push up process.

When my normal developing time with caffenol similar strong (4 portions of unused instant coffee and 10x250 mg vit. C in tabs) is 15 minutes, here I decided the basic time to 30 minutes (10 portions of once used coffee and without the second developing substance). Because of 2x push-up (which means time x1,6 and x1,6 again) the final time was near 90 minutes. But with normally exposed negative film should be 30 or 40 minutes enough.

I had one problem - bad wash of antireflex layer in fixer. I must use fixer again for longer time. My advice: fix it 20 minutes.

Result: It works. You can see whole process and final pictures here:

Remember: shooted at night, it's twice pushed up, without ascorbic acid - so it's with more noise and more contrast ... on the opposite side it is creative :-)

And yes - this is most eco-friendly and cheapest developer in the world :-)

jakebaldwin (author)woodc10002012-09-15

I've heard from a few sources that only unused instant coffee grounds work, but I'm not totally sure about the reason for it. Even if real grounds work for this process, they might be spent after being brewed once.

TechMidden (author)2012-09-01

Thanks for this. I had not heard of Caffenol before. Unfortunately I don't do much (read: any) film photography anymore.

Just a couple of things:

The developer does not pick up any silver or silver halides and it is perfectly safe to put Caffenol down the drain. Nobody should ever be dumping chemicals on the ground. That is the absolute worst thing you could do for the planet.

The fixer (thiosulphate) is essentially benign and non-toxic. It's this solution that dissolves away the silver halides that have not been developed into elemental silver. This also can and should go down your drain. Silver ions are not toxic to life and will soon react with other stuff to make insoluble silver salts.

Finally, read the package to determine how many times a batch of fixer can be used - don't just throw it away after one or two uses because it's good for much more than that.

Chip Mahoney (author)2012-07-24

I use paper film for pinhole photography. Can I use Caffenol to develop the Ilford iso100 paper with this technique. Also are there any DIY fixers you can make?


Jugfet (author)2012-06-27

I have had excellent results using Ilford HP5 roll film, very contrasty results and easy to print negs. Prints turn out really nice in Caffenol, whichever flavour you care to mix up. However....I did try a cheap brand of instant coffee from Tesco (value range) and got ZIP! I then used their gold top coffee, still cheap, and had super prints. Good definition and wonderful gradation across the board.
The smell can be a bit strange once the stuff is mixed up, but if you are used to working in a darkroom with B&W chemicals it's nothing to gripe about.
A friend said he had just tried it with Fuji Neopan and was ecstatic about the resuts.
A chemistry lecturer I know said that theoreticaly, you could get similar results by using Cocaine as a reducing agent (developer) ; Just a little too expensive for me I think.
As for the availability of washing soda (Sodium Carbonate NOT Bi-Carbonate) in the USA, Walmart has it by the hundredweight in the cleaning section.

jakebaldwin (author)Jugfet2012-06-28

So far, I've liked the Ilford film, though I haven't had many other rolls for comparison. I've been using old expired rolls that have been lying in a fridge for years (all Fuji and Ilford).

do remember reading a rumor about cheap instant coffee being much worse for developing than "better" instant coffee, but I haven't seen any evidence behind it. Seems like another interesting topic to look further into. Maybe more experimentation is down the road, though I really don't want to imagine all of the potential variables in distinguishing between coffee brands and roasts. 

To wrap up: 
It smells like death.
Did your friend follow this Instructable, or one of the many other articles on the net?
I don't think I'll be developing with cocaine any time soon.
Good to hear about Walmart. I found my small box at our local Ace hardware.

Thanks for your comment!

Jugfet (author)jakebaldwin2012-06-28

I didn't know anything about the qualities of coffee for developing and thought that all coffee would contain the basic ingredient for reducing the silver salts.
By the way I'm UK based - I was taking an A level in photography and chose the coffee thing as a project for the personal investigation element. The lecturer knew nothing about it so I was basicaly out on my own as far as experimentation was concerned. This is where I wasted a couple of hours in the college darkroom first of all thinking I had made the classic mistake of placing the paper the wrong way up on under the enlarger, or not giving enough exposure or having mixed up the caffenol wrong. Once I had cottoned on to it being the 'soup' things developed nicely - no pun intended.
Exposure needs to stay the same as if you were using a normal developer, it's the development that may take a little longer.
Be patient and don't expect the image to start appearing quickly.
Development I would liken to using old out of date Bromide paper, it is slow and steady.

doctorbigdaddy (author)2012-06-23

Thank you Jakebaldwin and especially Imagemaker for a great exchange that was very helpful for us old Black and white Photographers. i have a Wista 4x5 view camera and can't wait to try Caffenol and Caffenol-C.Ithink that I will use the sleel wool trick and then add Liver of sulfur out doors to the remainder; you could then discard the fluid into a flower bed as one of the commentators mentioned.What a great Instructable .Thank you both!

chaydgb (author)2012-06-21

The problem with using computers to do photographic effects is that ther's not really a challenge to it. Besides, when you consider the amount of pollutants released to power the aforementioned computer, plus all the non biodegradable materials taken to make both it, the digital camera, its batteries and any printer (if used), I feel that the film camera still comes out as greener in the end. Also film cameras, can be brought secondhand, and thus be saved from going to landfill.

swander (author)chaydgb2012-06-21

Yikes, digital is more eco-bully than Developed film? Check your stats. SLR's use the same batteries (sometimes mercury batteries, eek!) they use the same materials in the build (metal, plastic, LCD, etc) and they manage to produce more plastic garbage over their lives to fill a wastbasket (read cardboard film boxes with huge backplanes so they hang nicely from the store shelves) plastic film cans that seem to disappear after you develop the film along with the cap unless you make salt and pepper shakers from 2) and the nasty chemicals that have been mentioned in this article along with the 1000's of poison finished photos that we all cherish. Digi is an eco-dream, you can recharge the batteries with a solar cell along with your laptop and have a 10,000 pic slideshow in the middle of the Sahara without the trunk of photo albums required. Digital photography is here to stay, and 35mm film will be here for a few more decades too.

theo67 (author)2012-06-21

What is film?

swander (author)theo672012-06-21

Washing soda is about as common as gold dust here in USA, mostly it is a special order but it can be had.

jakebaldwin (author)theo672012-06-21
tjesse (author)2012-06-21

The reason the old film effects are available, is because they are cool enough to copy. I don't develop my film but I do enjoy my Polaroid pack-film camera. Digital has downfalls, finding the shoebox full of pictures in a closet will soon be replaced by finding a dusty hard drive. We have tons of DVDs full of pictures and none feel like memories because it lacks risk. We can take 27 pictures of one person to find the right "look", then you can make 1000's of digital duplicates. You can't miss what you never experienced. Take a disposable camera to one event and leave the digital camera at home, I promise those pictures will be more fun.

jakebaldwin (author)tjesse2012-06-21

You've got it. I started into film photography primarily for the price gap between film and digital. I received two old SLR cameras as hand-me-downs and used them before my digital point-and-shoots. To get the same kind of control and flexibility with a DSLR that I could get with an older analog model, I would've had to fork over hundreds or thousands of dollars. Even now, with nicer options available, I stick with my cameras for the fun and beauty of taking a couple moments to set up an exposure and shooting nice pictures. Developing my own film has brought a new ritual to photography for me, like brewing tea or coffee. The environmental aspects are just a bonus.

Skor459 (author)2012-06-21

Yay for Marin Filmworks!

billbillt (author)2012-06-21

I am still a fan of 35mm film photography...Thanks for sharing this!...

ravenking (author)2012-06-21

Even though I feel that I bloomed in the digital age with digital cameras and GIMP, I think film will still continue to be a viable art medium.
I think this instructable is very creative.

spark master (author)2012-06-21


Johenix (author)2012-06-17

Now this is an interesting "McGyver" trick.
For a stop ath I would use household vinegar- standard acetic acid.
How would I deal with the silver in the spent developer and fixer?
I think I might put a pad of steel wool in the spent chemicals for a day or so. Iron is less toxic than silver.
In the color developing busness we put out excess spent chemicals trickeling through two 5 gallon buckets of steel wool before it went into the sewers to get the silver out.

Johenix (author)Johenix2012-06-21

In the color development buisness (1975-1992) our " Blix" (Bleach-Fix) which removes the undeveloped silver halide and the metalic silver that results from the color immage formation was mostly recycled by passing it through an electrolosis machine with positively charged carbon electrodes and a negatively charged rorating stainless steel drum that became coated with silver.
(Once a month or so we would shut down the cell, remove the stainless steel drum, and tap it with a mallet to break off the quarter inch thick layers of PURE SILVER that covered it.)
Once the chemicals passed through the electrolosis cell, a small portion was discarded into the sewer after passing through two 5 gallon buckets (in series) of steel wool.
The remaining chemicals were aireated and strengthened with a regenerating solution before being reused.

Hypo could be desilvered before being discarded by putting it in a closed jar with a pad of steel wool for 24-48 hours or by taking it out doors and adding liver of sulphur (sodium sulphide) to it to precipitate silver sulphide (BEWARE: Poisonous Hydrogen Sulphide gas is produced).

ImageMaker (author)Johenix2012-06-17

There's no silver in the developer in this case (it's different if you use a commercial developer that contains sodium sulfite, but there's none of that in Caffenol-C). The fixer can pick up enough silver with multiple uses to actually be economically viable to recover the metal; that's usually done with electrolysis, in commercial processes. Sorry to say, Johenix, that if your color lab was trickling chemicals into the drain they were violating EPA regulations; there's no restriction on home hobby photographers putting chemicals down the drain (and neither spent developer nor once-used fixer are significant environmental hazards), but in business, it's another story, mainly because of the expected quantities.

For home photographers, I wouldn't even both with stop bath, and you can buy sodium thiosulfate from pool supply stores sometimes; it's sold for reducing chlorine (unfortunately, sodium sulfite is also sold for this purpose, so unless you're sure which you're getting, I wouldn't get it there). You can also buy sodium thiosulfate at a number of online chemical dealers; it's not considered hazardous for shipping, so five pounds with shipping won't cost a bunch. I mix one ounce (by weight) of the thiosulfate in a quart of water (or 30 grams per liter, if you're metric), use it once, and put it down the drain. The silver will plate out in the first metal pipe it encounters, and the thiosulfate will oxidize to sulfite or sulfate, in harmless quantity (assuming you're not developer dozens of rolls of film per week).

Oh, I might also mention -- though I didn't invent coffee developers, I did originate the name Caffenol and Caffenol-C is originally my own innovation.

jakebaldwin (author)ImageMaker2012-06-18

Wow! I'm intrigued by the idea of using steel wool, but I'm still wary of putting anything down the drain. In the Bay Area, you never know what goes to the water. While some things might be safe to dump, I had forgotten which chemicals carried all the nasties. I'm also very interested to read that fixer has some potential use after a few rounds. The tank I'm on at this point has been used maybe three times.

I'm still wondering about where the silver hallides end up, though. I was under the impression that the developer, whether it was conventional or not, stripped hallides from the film. The stop bath and fixer just picked up leftovers with the other functions they served. Right?

Also, ImageMaker, I'm not quite sure what you meant in your second paragraph. What do you use the thiosulfate for?

ImageMaker (author)jakebaldwin2012-06-18

With conventional developers, the sodium sulfite (added as both a preservative, to allow storing the developer, and as a grain reducer because of its mild halide solvent properties) picks up a small amount of silver, but the bulk of undeveloped halide (all of it in low- or no-sulfite developers) is removed by the fixer regardless of the developer used. The primary function of developer is to convert *exposed* halide into metallic silver -- while you could consider this "stripping" halides, if you develop unexposed film, the developer does nothing beyond the slight solvent effect of high levels of sulfite, if present.

Sodium thiosulfate is the most basic fixer ingredient -- a simple solution of just sodium thiosulfate in water makes "plain hypo" fixer, which will fix "conventional grain" films (older types like Plus-X, Tri-X, Ilford Pan F, and so forth -- ones with cubic halide grains) in 8-10 minutes at common developing temperatures. Plain hypo can be used one-shot at 30 g/l strength, or it can be mixed at 120 g/l and sodium sulfite added at 25 g/l, and reused just like commercial fixer sold as a bag of dry ingredients (typically ten or more films per liter; the actual rule is to fix for twice the time required to visually clear the film, and discard fixer when the clearing time has doubled from the original value). Many modern commercial fixers are "rapid" types, based on ammonium thiosulfate; they work about twice as fast, and are the only kind usually recommended for use with "delta" or "T" grain type films such as Ilford Delta 100 and Kodak's T-Max family. Ammonium thiocyanate also works as a rapid fixer, but is much less available and more expensive, so it's seldom used.

In fact, it is possible to fix T grain or delta grain films with plain hypo, if you use a two-bath fixing process -- put the film into the first bath, and when it's nearly cleared (light exposure doesn't matter if it's not going back into a developer before fixing is completed -- you can turn on the lights or open the tank once the film has been in fixer for one minute), move it to the second bath and leave it for the same amount of time the first bath took; for this method, you should mix 120 grams of sodium thiosulfate per liter and add 25 g/l of sodium sulfite as a preservative, reuse the fixer, and after fixing ten films (135-36, 120, or 8x10 equivalent in sheet film or other sizes) discard the first bath, replace it with the second, and mix fresh fixer for the second bath.

As for stop bath, the primary purpose it serves is to give a precise "stop" time to the development -- and the development rate is generally so slow at the end of standard developer times that this matters very little, if at all, compared to the slow exhaustion of the tiny bit of developer that carries over in the emulsion and continues to work until fixer removes all the halide it could develop. There are good arguments to be made that the shift from alkaline developer to acidic stop bath and fixer (commercial fixers are almost as acidic as stop bath) is bad for the emulsion compared to using a mildly alkaline fixer (plain hypo, or hypo plus sodium sulfite, is less alkaline than most developers, but definitely not acidic). A secondary purpose of stop bath is to limit developer contamination of the fixer, but if, as I do, you mix your fixer weak and use it only once, this doesn't matter (and it matters very little anyway, for the reasons given above); if you're reusing your fixer and are concerned about it, a plain water rinse (fill the tank, agitate for ten seconds, drain, repeat twice more) will prevent carried over developer from being a problem before your fixer is exhausted.

jakebaldwin (author)ImageMaker2012-06-19

Thanks very much for all the info. I had forgotten all about the actual conversion of halides into metallic silver. Super helpful!

I've been reusing my fixer and rinsing the tank after developing. I'm not using a chemical stop bath. The fixer is the only chemical taking away silver, right? Is there any benefit to using plain hypo fixer over conventional fixer? I think one of my primary goals is reducing the nastiness enough to dump everything without remorse.

ImageMaker (author)jakebaldwin2012-06-19

Unless you've using a high sulfite developer like D-23 stock, D-76 stock, or XTOL stock (all at 100 g/l sodium sulfite concentration), the fixer is the only bath that remove halides from the emulstion. The halide in fixer can eventually develop out from carried over developer or sufficient light exposure; I've got a fixer jug that has a layer of silver plated inside, enough to be a bright mirror if it weren't a translucent polyethylene bottle.

The main benefit of plain hypo over commercial fixer is cost. I figure my one-shot hypo, at 30 g/l with no sulfite (preservative isn't needed because I'll discard the solution within an hour of mixing it) costs around a nickel a roll; if I make reusable fixer with sulfite, the cost goes down a little further. Commercial rapid fixer runs 4-5 times that figure. The other advantage of one-shot fixer at the lower strength is just what you're after -- the amount of silver and thiosulfate per liter of water is very small (you'll get around 1 gram of silver per roll from fixing normally exposed film), neither one has a long life in a sewer system, and residual silver is very efficiently caught in the coagulation and settling stages of sewage treatment (though too much of it can negatively affect the bacteria that do that job, it'd take kilograms in a settling pond to cause trouble).

Caffenol C is hardly any worse -- everything in it would normally go down drains in one form or another anyway: laundry soda, coffee, and vitamin C (the latter of which quickly oxidizes to equally harmless simpler organics in a sewer environment) are harmless enough you could actually drink small quantities of the stuff without harm (though I wouldn't suggest it; the washing soda probably tastes pretty nasty).

It is important to ensure dogs don't ingest fixer or its immediate residue -- thiosulfate is pretty toxic to them -- but that's not usually a problem unless you spill it in their food.

ImageMaker (author)jakebaldwin2012-06-18

Oh, yeah -- steel wool works well for treating exhausted fixer; the silver plates out onto the steel (same thing that happens in the pipes if you put your fixer down the drain), and the solution that's left can be filtered, if desired (to minimize metallic silver carried over), and then poured in a flower bed; the sulfur (which quickly changes form to sulfate in the soil) is very welcome for roses and the like.

Nirgal38 (author)2012-06-19

This is nothing short of completely awesome. I've been processing film since 1977 and even did it in the Air Force for reconnaissance (in this digital age, my AFSC is now obsolete).

I'd be interested to see how this process works on prints. Might have to break out some of the old gear to give it a try.

Please tell me you entered this in the analog photo contest, too.

jakebaldwin (author)Nirgal382012-06-19

I remember reading about printing with Caffenol, and it seemed to work out pretty well. I wasn't expecting the prints to be as clear as they were. I'm planning on trying the technique out when I get the chance. 

Yes, I entered this in the Analog Photo Challenge and the Green Tech Contest.


I wish I could of found this before I bought my developer.

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