Caffenol Black is a minimal developer that uses only coffee as developing agent, Sodium Carbonate as accelerator and Sodium Chloride (salt) as restrainer. The recipe is as follows:
10 g soluble coffee
3 g Sodium Carbonate
2 g Sodium Chloride
Water to make 500 ml
Preparation: Dissolve by the given order in tap water (16-18ºC) and wait some minutes until all graininess is gone. Develop for 90 minutes, agitating each 15 minutes for 1 minute.
And here are some of the results you may expect:
The photos above were taken with a Olympus Trip 35 using Fomapan 100 (bulk).