Caffenol is a photographic alternative process whereby phenols, sodium carbonate and optionally vitamin C are used in aqueous solution as a film and print photographic developer.[1][2]
Other basic (as opposed to acidic) chemicals can be used in place of sodium carbonate; however, sodium carbonate is the most common.[1]
There are many formulas for caffenol, all based on preparations that contain caffeic acid (i.e., coffee or tea) and a pH modifier, most often sodium carbonate.[2][3] The chemistry of caffenol developers is based on the action of the reducing agent caffeic acid, which is chemically unrelated to caffeine.[1]