My basic caffenol recipe pr 1000 ml: 125 ml instant coffee, 100 ml crystal soda (or 35g only, if water free soda is used), 20ml c-vitamin. For high ISO films and stand development, also add 20 ml salt (iodized) . 11-15 min. at 20 celsius. See full recipe below.
High quality and fool proof Caffenol developer for black & white films.
After 1 year of caffenol experiments - trying out variuos strenghts, compositions and agitation methods with various black & white negative film, I have now come up with a a favorite mix and method that works really well with my prefered films, Kodak Tri-X, Ilford Delta and Kodak Double XX (5222). Actually, it works GREAT! Here it is, my new favorite Caffenol recipe:
“Caffenol 35”, my house recipe
(For 1 liter Caffenol 35)
125 ml instant coffee (40 g) or 1 liter tripple strength coffee.
100 ml (80g) crystal soda (crystal soda contains lots of water, so equivalent to apx. 35g/50ml water free soda)
20 ml (20g) C-vitamin
Optional, 20 ml (25g) iodized salt .
For high ISO films or long developments (push-developments and stand development), I use iodized salt as a “restrainer”, instead of the often suggested “potassium bromide”. When restrainer is used, more developing time is needed. See my favorite times below
Temperature of mix should be 20 degrees celcius.
Development times
In small tank, agitation all first minute, then 5-10 sec agitation every minut):
without restrainer: apx. 11min.
with restrainer apx. 15 min.
Procedure
I dissolve the instant coffee in a little boiling water, then I add some cold water and disolve the crystal soda into the still warm coffee mix. Stir constantly for at apx 3 minutes. Add salt and stir until liquid is totaly free from from any soda or salt crystals.
Add all the remaining water (cold) before adding vitamin-c. This is important to avoid “frying” the ascorbic acid in a liquid too alkaline.
I cool down the temperature to 20 degrees celcius with a few ice cubes is needed.
Use instantly or at least within 15 minutes. Oxidation ruins the caffenol developing powers.
Measure by volume made easy
For my steel tank, I only need 250ml developer for one 35mm film. I found a way to measure up all the ingredients real easy using an empty film container to measure the amount I need of both coffee and crystal soda, and a measuring teaspoon (5ml) to measure for both vitamin-c and iodized salt (if nedded). Set a mark on the film container, where volume is 25ml.
So for one film/250ml “Caffenol 35” I use this:
1 film container of instant coffee, dissolved in a little hot water
1 film container almost full (at 25ml mark) of soda crystal
1 tsp (5ml) of vitamin-C
Optional, 1 tsp (5ml) of iodized salt only for high ISO films.
Of course, if you want to make 1/2 liter you will need twice the amount etc. Usually the volume you need is written on the bottom of the tank, or you can meassure it up yourself.
Some DIY developers (people) believe in more exact meassurement, preferably by weight. But I find that exact meassuring in caffenol making is somewhat misleading. Because the main ingredients used in caffenol aren’t exact in strenght/potency either: Coffee and soda really vary in strenght. You have to “get to know” your own stable of ingredients, and when you know how strong your coffee is and how pure your soda is, and knowing this, you might as well meassure by volume. The “crystal soda” I can buy locally contains so much water, that I need 2,5 times more of this soda than If I had used “waterfree soda” as is listed in most recipies. (I found out by baking the soda I had until it didnt loose any more weight/water).
What kind of coffee?
Its the caffeic acids and also other phenols present in coffee beans, that works as a developer. Not the caffeine.
There is a common advice among Caffenol-people, that the cheapest possible instant coffee is the best. Thats a bit misleading. The advice, stems from the fact, that cheaper coffees are often made from “robusta” beans, and not from the more expensive “arabica” bean. And it so happens, that generally robusta beans have a higher content of caffeic acids than arabica beans. To counter this advise, cheap instant coffees can be fabricated badly from beans growning in poor soil, and it can also be roasted and fabricated too long ago, The phenols decompose over time, and the ph I can really t
Alternatively to using instant coffee, I often make a very strong coffee of the same kind I normally drink, just much stronger. Probably three times stronger, thar what I do for normal drinking. I make fine coffee powder in a coffee grinder and make either filter coffee, or I brew it in a bistro style pot for extended time and then filter it through an ordinary coffee filter after. For this method, the coffee should make up all your liquid - no extra water. Cool it to 20 degrees celcius before use.
What about the vitamin-c?
You want 100% pure ascorbic acid. When mixed with sodium carbonate, sodium ascorbate is formed, and THAT works as a developer too together with the phenolic compound in the coffee. Sodium ascorbate decomposes by oxidation, so thats why you must use the caffenol mix when its fresh made. Even after a few hours its no good anymore.
High image quality - even with high speed films.
Kodak Tri-X shot at ISO 320, developed in Caffenol 35 with iodized salt, only 35 grams waterfree soda pr. liter. 15 min dev. time.
Ilford Delta 400. Note that clear parts in frame and outside frame is quite clear. Very little fog/toning from the caffenol developing, while the dark areas on film (highligts when positive) are both dense and detailed.
Learn from others - and yourself
See this publication online: http://www.caffenol-cookbook.com
Like many other Caffenol heads, I refer to and really like the Caffenol Cookbook, but actually this “bible of caffenol” contains many different recipies, so its important to make my (your) own experimentation to find out what strenght, “composition” and developing method is your working caffenol receipe for your choice of films. The Massive Development Chart also lists dev. times for Caffenol development, but does not actually specify the recipe used, and does not give you choises of development method, So I made up my own favority mix by trial and error. The main challenge has been to achieve a dense negative for intense highlights, but avoid a foggy film, with no real clear parts. The result is my “house recipe” (see above) which is weaker (less soda) than the Caffenol CM (rs) reduced soda version, but stronger than Caffenol STD Delta recipe. (You can find both these recipes and more in the Caffenol Handbook.
You can read my first and longer post on DIY Eco film and paper developers here (in danish) https://www.peterbjerg.dk/blog/eco
Links
The-Caffenol-Cookbook-Bible-Recipes-and-Tutorials.pdf - A really great guide to how and why caffenol developers work. In the online version, there are many beautifull photo examples. And you can also download the PDF, this version is without photos, but include all the recipies and explanations. https://www.facebook.com/groups/caffenol - Large and active facebook group.
http://www.caffenol.org
http://caffenol.blogspot.com
https://www.dagiebrundert.de/ECaffenol.html - This page has examples of the many alternative natural ingredients that will work as developers when mixed with soda and ascorbic acid (C-vitamin).
https://www.ilfordphoto.com/beginners-guide-processing-film/ - A greatr basic guide to home developing, just swap out the commercial toxic developer, with your own eco friendly developer.
https://people.rit.edu/andpph/text-coffee.html - The research article from 1995 that started it all. From Rochester Institute of Technology.