Caffenol: develop with coffee

Coffee, vitamin C and washing soda

Caffenol works thanks to the chemistry of coffee: the phenolic compounds in instant coffee act as reducing agents, converting exposed silver halides in the emulsion into visible metallic silver. Sodium carbonate raises the pH and activates the reaction; vitamin C boosts the action and helps control fog.

Unlike other alternative developers such as Guinneol or Wineol, Caffenol is surprisingly stable and predictable: the same recipe and conditions give consistent results every time.

The recipe

For a standard 35mm tank (500 ml):

• 14.5 g instant coffee — not decaffeinated
• 20 g sodium carbonate (Na₂CO₃ — washing soda) — not to be confused with caustic soda
• 1.8 g ascorbic acid — vitamin C powder, from a pharmacy
• Distilled water to 500 ml

Prepared in two separate solutions — carbonate on one side, coffee and vitamin C on the other — then mixed just before developing. Standard time: 15 minutes at 20 °C.

Key topics

• Chemistry of Caffenol: why coffee develops film and how each ingredient works
• The Llumàtics formula: doses, ratios and why they work
• Two-solution preparation (A+B) and stabilisation time
• Full development process: temperature, agitation and timing
• Rinses, fixing and final wash
• Reading the negative: density, grain and contrast
• Colour scanning: how to get the characteristic warm, reddish tones of Caffenol

Included in the price

• Instant coffee, sodium carbonate and vitamin C
• Use of the developing tank, spiral reel and darkroom bag
• Fixer and washing products
• Use of the scanner for the final check
• Refreshments

What to bring

• An exposed 35mm B&W roll (ISO 100 or 400 recommended — Fomapan, HP5, Tri-X)

Not included

• The 35mm roll — it must be yours and already exposed. If you don’t have one, you can buy one at Llumàtics (12 €).
• Full roll scanning (available as an add-on to the Scanning workshop or as a tutorial from 20 €)

Want to do all three organic developers in one session? Caffenol, Guinneol and Wineol can be combined in a 4-hour session. Write to us and we’ll organise it.