Recipe and Instructions

Chemical Amount
Instant coffee 20g
Ascorbic acid 5g
Sodium carbonate (anhydrous) 13.5g
Water to 500ml

Fix
120g + water to 500ml

Mix order: water, then soda, then ascorbic acid, then coffee. It foams a bit when the ascorbic acid and soda meet, so go slowly.

Large thiosulfate crystals dissolve slowly and chill the water as they go. Use warm water (~40°C) and stir, or crush them first.

Standard caffenol-C development is around 15 minutes at 20°C with agitation for the first 30 seconds and a few gentle inversions each minute. Time varies by film and coffee strength, so use it as a starting point.

Mix the developer fresh and use it one-shot.