I don't think Caffenol meets my definition. What is the actual developing agent, how much of it is contained in a given quantity of coffee, and how do you know? What is the chemical composition of coffee, and how do its components contribute to the working properties of a developer made with it? If these things are known with any certainty, I've never seen a published description. I understand the novelty of making a working developer from household ingredients, but I also understand the limitations of that approach, and frankly don't understand the persistence of the attraction beyond its novelty. Any and all of the developers listed at the bottom of your message are more effective and more reliable, and most are published formulae. Just calling a spade a spade.