Guinneol: develop with Guinness

A can of Guinness and pharmacy chemistry

Guinneol is essentially a Caffenol made with stout beer instead of coffee. The chemistry is the same: the polyphenols in Guinness act as an organic developing agent, washing soda accelerates the process, and vitamin C boosts activity and reduces fog.

It’s not a precision developer. It’s an experimentation developer — and that’s exactly why it’s worth learning.

The recipe

For a standard 35mm developing tank:

• 440 ml of Guinness — the standard 500ml can also works
• 50 g of washing soda — do not confuse with caustic soda
• 12 g of vitamin C — pure ascorbic acid, from a pharmacy or health food shop

Key contents

• Chemistry of Guinneol: why it works and how it differs from Caffenol
• Preparing the developer: mixing, temperature and controlling clumps
• Full process: pre-wash, development at 30°C for 15 minutes, stop bath, fix and wash
• Agitation technique: 1 minute continuous + 10 seconds per minute until 15 minutes
• Reading the resulting negative: characteristic density, grain and tone
• Colour scanning: why it gives better results than B&W with these negatives

What’s included

• Guinness, washing soda and vitamin C
• Developing tank, spiral and changing bag
• Fixer and washing products
• Use of the scanner for a final check
• Refreshments (coffee or tea and fruit — and maybe a bit of Guinness)

What to bring

• One exposed 35mm B&W roll (ISO 400 recommended — Lady Grey, HP5 or similar)

Not included

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

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

Frequently asked questions