I used 20 g of coffee with 10 g sodium sulfite in 1 liter solution and added only 1 g Sodium Hydroxide as alkali. I also used 0,2 g of Potassium Bromide and developed for 90 minutes at room temperature. The black and white pictures that resulted are very poor, but if you scann them as color negatives and adjust in software afterwoods, you may have a big surprise. The film must be very well washed after fixing to remove coffee stains but it remains yellowish, similar to color negatives.
|A poor Black and White picture|
|The same picture scanned in color mode|
|From the same black and white roll|