I am very hooked on trying this, and I have found some recipes for some devs. But I am working on a concept for a coffee shop in Århus, Denmark who wants some pictures taken in the coffee shop. And then I want to develop the negs with the addition of his own, hand brewed coffee. Developing these negs in instant coffee would be blasphemic to him, as a barista hates instant coffee.
Can anyone provide me with a recipe with already made coffee instead of instant coffee?
Should I just add some washing soda to the cold coffee and experiment?