Caffenol Film Developer

Caffenol is an informal name for a category of black-and-white film developers made with coffee and other household ingredients. There are many recipes for developing film with Caffenol, but some common factors and knowledge apply to all of them. Getting great results with Caffenol is absolutely possible; you can match or beat some of the best commercial film developers if you know how. This article shares some of the things I have learned about Caffenol after using it as my main film developer for years.

Nothing I write in this article is new or original; it’s just that I had to learn it by poring over a lot of resources that were written as stream-of-conscious during those intense years of discovery. This article is simply my attempt to bring you, the reader, up to speed quickly and concisely.

I also want to encourage you to take another look at Caffenol if you’ve seen things that haven’t impressed you. It’s true that a lot of people who have written about Caffenol have shown negatives no photographer who cares about their work would want to produce. However, if you are at all interested, please look a little deeper. The ugly, all-but-ruined negatives frequently shared in Caffenol articles (sadly, often on the most high-profile websites) are not the best you can do. You can produce amazingly good negatives with Caffenol. The photo below shows the dramatically better results you can get by following the advice of those who’ve figured out how to do it. (Actually, the photo makes both negatives look bad, but just trust me, the second one isn’t as overdeveloped as it seems. That’s just the limits of the lighting and my iPhone’s camera.)

If you want to try Caffenol—and I encourage you to try it—you might save a lot of time and frustration by looking through this article. In particular I have tried to summarize the most common reasons for poor results. However, I am not responsible for anything that happens; use the information in this article at your own risk.

What is Caffenol?

Caffenol today means a developer mixed from instant coffee, sodium carbonate (usually just called soda, or washing soda), and Vitamin C, with optional extra ingredients depending on the recipe.

Caffenol was (re)invented by a chemistry class¹ in the 1990s, attempting to recreate techniques used by soldiers and journalists during wartime. The resulting recipe was instant coffee with agents to increase pH. I think this remained a curiosity for years until at some point interest grew to a tipping point, and a handful of important improvements were discovered and well-known recipes were developed.

Around 2010, awareness of Caffenol grew much more rapidly, a core group of interested photographers self-assembled, and a few resources became available and widely known. The most important of these are:

• The Caffenol Cookbook Bible, a 40-page PDF file with many recipes. Originally published on a now-defunct website caffenol-cookbook.com; now available via Wayback Machine and other sources such as e.g. caffenol.org.
• Several websites written by some of the participants in the Caffenol renaissance, including https://www.caffenol.org/ and https://caffenol.blogspot.com/ among others.
• Plenty of forums and e.g. groups on social media sites such as Flickr.

Most of the websites and forums dedicated to Caffenol have tapered off or gone quiet since about 2015. This does not mean, however, that nobody cares anymore. It’s just that the period about 2005-2015 was the zenith of experimenting and improving Caffenol. At this point, most things you might want to do with Caffenol are well documented, and I’m not sure there is widespread need for further invention or experimentation. Of course, there are still niche cases like an obscure film for which nobody has yet shared a working recipe.

Why Caffenol?

I first tried Caffenol out of curiosity, but quickly realized it’s much more than a fun experiment, and there are many good reasons to use it seriously, even for commercial work. In no particular order:

• It’s less toxic and more environmentally friendly. Many commercial developers contain things I don’t want to put in/on my body, don’t want to store in my living area, and don’t want to flush down the drain into the environment.
• The ingredients are readily available. I have gone to the grocery store while traveling, on the spur of the moment after business hours when there’s no possible way to buy D76, and mixed a great-quality film developer in 15 minutes.
• Most importantly for me, the results can be not only top-quality, but actually you can get very distinctive looks and tonality. There are Caffenol recipes that produce truly wonderful effects in shadows, midtones, highlights, grain, sharpness, contrast, etc. You can create incredibly natural-looking images, otherworldly-looking images, and anything in between. The resulting images can be visually striking—the type of thing you might struggle to achieve in other ways.

Core Recipes

Many, many recipes exist, and a lot of people have their own that works for them. However, some recipes have become more-or-less standards and have well-known names. Here are a few of them.

• Caffenol CL is a weak general-purpose developer with long development times, for fine grain, low fog, and controlling difficult lighting. My personal favorite.
• Caffenol CM is a fast, easy, forgiving, general-purpose recipe for most films up to about ISO 100.
• Caffenol CH is for high-speed films.
• Caffenol 35 is a general-purpose recipe for slow and medium speed films, with more-or-less normal development times.
• Delta-std and Delta-micro are recipes for general-purpose films and special-purpose microfilms, respectively, with shorter development times.
• Caffeafine is a two-bath developer named after Diafine.
• There are variations on many recipes, such as -RS recipes with lower amounts of some ingredients for fine control over contrast and other effects.

Feel free to research some of these. As time passes I hope to produce in-depth writeups of more of them myself. For now, if you see one listed above that I have not linked, I can suggest looking here and here as starting points.

Key Cautions

I have noticed common problems as I read through hundreds of articles, blog comments, and forum discussions about Caffenol. In addition, I have made one or two of my own mistakes. Here are some of the key points to keep in mind for best results.

1. By far the most common problem is using the wrong amount of sodium carbonate (washing soda). This is because sodium carbonate² exists naturally in several forms, which contain very different amounts of water, thus greatly changing its weight. Over and over I have seen people try, unsure what they have, and get blank negatives; then discover their washing soda is different than assumed. This is a pity because it’s actually easy to figure out the water content of your soda (anhydrous-equivalent weight). Simply measure 100 grams, heat it on a stovetop or in an oven for a while to drive off water, and weigh it afterwards. My first box of Arm & Hammer Super Washing Soda reduced from 100 to 90.5 grams after cooking (I cooked and measured repeatedly, until it stopped losing weight). Now, when I need an amount of washing soda for a recipe, I just divide the amount by 0.905. When I buy a new box I repeat this test, because each batch of soda can be quite different (my second box is 94.5%. Some people find their Arm & Hammer Super Washing Soda only loses 2% of its weight, for example. Others have found sources where they can buy completely anhydrous soda. Others report their soda is more than 50% water. Don’t take shortcuts—do the test, it’s simple. Also note that baking soda is not washing soda.
2. Use caffeinated instant coffee. Decaf instant coffee is less active. Caffeine actually isn’t the active ingredient in development, caffeic acid is; but decaf coffee doesn’t work as well as caffeinated. I use the cheapest instant coffee I can find in large bottles. I try to reduce the environmental impact of buying the coffee, keeping in mind things like the single-use plastic that is often how it’s packaged.
3. Use a recipe with restrainer such as potassium bromide (KBr) or iodized table salt if you a) want to avoid fogged negatives, b) want more even development, c) want to develop high-speed film, or d) want to develop for a long time with low agitation. If you’re getting dark, murky, uneven negatives, you probably need restrainer or a different recipe. Not all recipes are suitable for all films and timing/agitation schemes.
4. Use pure ingredients. Don’t take the chance with crushing up Vitamin C pills that are mostly fillers and coated with sugar. Don’t buy washing soda with fragrances. Get raw, pure ingredients that have the chemicals required, and nothing else. Use distilled water to mix chemicals, and as a final rinse, if at all possible.
5. Note carefully whether the recipe tolerates imprecision. Some recipes require exact measurements and/or timings. Amounts of KBr, in particular, usually need to be very precise or you’ll get completely blank negatives. If you see a recipe that lists ingredients in informal units of measure like “spoonful” or “fill a film canister half full,” I suggest skipping it and using a recipe that has repeatable, well-defined quantities. There are hundreds of blog posts with a heaping teaspoon of this and a farthing of that; if they’re lucky, they’re getting good results by accidentally being similar to a recipe whose quantities you can actually know. You’ll have better luck, especially when starting out, if you do that. I personally weigh all my ingredients with a scale that goes to 0.01 g, and I work in metric units.
6. Caffenol is only a developer. You still need to stop, fix, wash, etc as usual. If you don’t know what this means, you need to learn more about film development basics.
7. Know the basics of film development. If you don’t have good control of the basics (time, temperature, agitation, cleanliness and avoiding contamination, light leaks, fixer capacity, etc) you will get non-Caffenol-related development failures that you’d experience with any developer.

General Tips and Tricks

Here are some general things I have learned about Caffenol:

• It is best used as a single-shot developer (use once, discard, don’t reuse). I have seen people reporting that they can reuse it, but that it is much weaker for each reuse. For me, trying to determine exact capacity for reuse, and keep track of number of uses and how much to compensate, isn’t worthwhile; I use it once and dump it.
• It reportedly does not store well, and is best mixed fresh just before use. I have again seen people say they stored it for some number of hours or days and saw no ill effects, but I’ve also seen reports of rapidly changing effectiveness after it sits for some hours. The only personal experience I can add is that I have reused a batch overnight after developing only a small snippet in it during an experiment. I had success with this several times, but one time after sitting undisturbed for hours, I poured the developer into the tank without re-mixing it, and the negatives were almost clear. So apparently some of the active agents settle out. Since then, I have always made sure my Caffenol is mixed well just before pouring it into the developing tank.
• I think it is a good idea to rinse your negatives and tank very clean before fixing. This helps keep the fixer clean and uncontaminated for multiple reuses. Personally, I don’t use a dedicated stop bath, I use a water rinse. I use the Ilford method of filling the tank, inverting 5x and dumping; repeat with 10x, 15x, 20x; finish with a distilled water rinse to get the tap water minerals out of the tank. Even after 25 rolls, my fixer remains clean and isn’t stained with leftover coffee.
• Reports and opinions vary about the right order to add the ingredients. I can only note that after you add the coffee, it becomes impossible to see whether any subsequent ingredients are completely dissolved. I add the coffee last, after I make sure no crystals of other ingredients remain.
• Caffenol can be a bit foamy and viscous depending on the recipe, and sometimes instant coffee will have small grains that refuse to dissolve. I always mix a bit more volume than I need, so that I can a) make sure there is enough in the tank to generously cover the negatives even if some of the volume turns to foam with agitation; b) leave a bit in my mixing container so I don’t pour the occasional undissolved granule of coffee into the tank with the film.
• Some ingredients are much more convenient to keep as diluted stock, rather than measuring in powder form. I heartily recommend making a 10% solution of anhydrous-equivalent washing soda in distilled water, and keeping a bottle of it. Washing soda takes a while to dissolve, so this makes mixing Caffenol much more convenient and quick. Simply place your mixing container on your scale, zero the scale, and add 10x the weight needed; e.g. if you require 4 g of soda, pour in 40 g of the 10% solution. (A 10% solution means 1 g of solute for every 10 g of solution; for example, to make 1000 g of 10% soda solution, start with 100 g of anhydrous equivalent soda and add water to total 1000 g).
• I pre-weigh batches of dry ingredients every couple of months, keeping them in small, labeled, airtight containers for ready use. I have found that vitamin C and instant coffee need to be kept in low humidity, so I store everything in ziploc bags with packets of dessicant. Conveniently, 10 g of the instant coffee brand that I use fits well into a 35mm film canister, and several of the recipes I use require 10 g of instant coffee, or multiples thereof.