What is Caffenol?

Question

I've been hearing about Caffenol and understand it's film developer (for example in these three questions ).

What is it exactly? How do I get it? How is it used?

Answer 1

Caffenol is a home-made developer that seems to be gaining popularity among enthuisiasts, especially due to non-toxic compounds and environmentally friendly footprint.

According to Caffenol @Wikipedia:

There are many formulas for caffenol. All are based on preparations which contain caffeic acid (i.e. coffee or tea) and a pH modifier, most often sodium carbonate.

And indeed, searching for "Caffenol recipes" yields many results. For example, @ToastHouse mentions the following recipe in a couple of the linked questions:

I use 10 teaspoons of Folgers Instant Coffee Crystals, 7 teaspoons of Arm & Hammer Washing Soda, and 1 teaspoon of Ascorbic Acid Vitamin C for the developer. I use a bit of Heinz Distilled White Vinegar mixed with tap water for a stop bath, and 8 oz tap water, 2 oz of Ilford Rapid Fixer for the fixer.

Note that development times are usually longer that off the shelf developers.