Lately, I've been intrigued with the alternative developers for different effect. I've ordered some Shanghai b+w film to play with. I've been researching Caffenol for developing film and paper. I can understand the washing soda and the ascorbic acid helping, but what exactly does the coffee do? Besides toning the neg and paper, can one develop without adding the coffee? What other substitute can be used? I even came across some users using tea and chai. If it's the caffeine - can you use Coke, Pepsi or Red Bull?