so lets start the show with my basic recipe and some words about the ingredients. You already know that Caffenol-C is made of instant coffee, washing soda and vitamin-C.
All recipes are based upon 1 litre solution, measured in gramms and milliliter (ml, 1/1000 of 1 litre). No teaspoons allowed here! No ounces, inches, quarters, barrels, °F etc. I only use international standard units. In many households you will find small measuring mugs f.e. for doing the laundry. These will be usable if they have scales. A weight scale will be of course a bit better, but is not neccessary.
UPDATE: You can use volumetric measuring with Caffenol-C-M, but NOT with Cafenol-C-L, that will be introduced later. Using a scale is HIGHLY recommended for every recipe.
If you live in a country using not international standard units, you have to calculate the amounts yourself. Sorry! Now here we go:
Instant coffee: granulate (crystals) with lot of air included. Buy the cheapest brand you can get. More expensive ones might not be so good. Get the "strong" labeled version if possible. Not the "mild" ones. The active substance in coffee is caffeic acid, that behaves similar to pyrogallol and is a very compensating developing agent. I tried some cheapest brands here in Germany from Aldi, Lidl and other supermarkets. They all taste the same (awfully) and I guess they are all made by the same company or at least the same method. So it shouldn't be a problem to get reproducible results. 200 gramms for 3 Euro.
Vitamin-C: ascorbic acid, the second active developing agent. Works similar like Hydrochinone, giving more contrast and is hyperadditive to caffeic acid. Also reduces fog and of course developing time. Whenever possible, buy pure Vitamin-C, small crystals. Here I buy 100 gramms for 2-3 Euro, available in any pharmacy. Don't use vitamin pills or tablets, there will be other substances added and you might have to adjust the recipe. Buy only pure crystals for reproducible results. Used also in a famous commercial developer.
Washing soda: sodium carbonate (Na2CO3), waterfree (anhydrous). Be sure to get the waterfree one, white powder. If you should have crystals, it is not waterfree and I do not recommend it. You need much more and depending on the kind of hydrate you must recalculate differently. Soda is used for making the solution alkaline, that is important for activating the developing agents. Available at drugstores, supermarkets, zoo shops, swimming pool suppliers. Here at drugstores less than 1 Euro/500 gramms.
Recipe for 1 litre Caffenol-C-M, means for medium fast 100 ASA films (adjust yourself for other quantities)
1. 1 litre water
2. 100 ml washing-soda or 54 gramms
3. 16 ml vitamin-C or 16 gramms
4. 160 ml coffee or 40 gramms
Dissolve one after the other in the given order. Wait until each agent is dissolved completely. Stir while adding, especially the soda should be added slowly for good solution. I use tap water, no probs so far. The dissolving of the soda will heat the solution for about 3 °C. Keep that in mind for a proper temperature. Little fogging of the solution caused by the soda was no prob so far. When adding the vitamin-C small bubbles will appear, wait until they have cleared before finally adding the coffee. This is important! Then add the coffee, stir well and let stand the soup for about 5 minutes. The coffee needs some time to dissolve perfectly. Do not store, use within 1/2 an hour.
Develop for 15 minutes at 20 °C. Agitation first 30 seconds, then 3 times each minute. Intermediate rinse or stop bath, fix and rinse as usual. Tested with TMax100 and Fomapan100 so far. Other 100 ASA films may need slight adjustments. Not recommended for ASA 400 films or faster.
1 litre will cost about 1 to 1.20 Euro. Of course you will need less for developing 1 film, so depending from film and tank size, 1 development will cost about 30 to 60 Euro-Cents. Rodinal stand development will be much less expensive, but Caffenol-C competes well with commercial developers and the results are outstanding. No joke!
More details and sample pics for Caffenol-C-M with the next post.
Important note for recipes: when I say "XYZ" I mean "XYZ" and not "ABC".
Now I need a cup of coffee.
Cheers - Reinhold