Sustainable Darkroom Practices: Rosemary Developer

Environmental responsibility is becoming essential for many artists, sparking a revolution also in the chemical-heavy world of darkroom practices.

Traditional developers typically contain toxic ingredients like hydroquinone, metol, and phenidone. Sustainable developers aim to:

• Reduce ecological harm by using biodegradable substances

• Create a safer working environment for those who work in the darkroom

• Keep historical photographic processes alive with a sustainable twist

What Are Sustainable Darkroom Developers?

A developer in photography is a chemical solution that reduces exposed silver halide crystals to metallic silver, creating a visible image.

Sustainable developers rely on naturally occurring compounds that possess reducing properties—typically polyphenols, ascorbic acid, and other antioxidants. These are found abundantly in coffee, tea, mint, clove, thyme, and rosemary, to name a few.

These plant-based developers often require the addition of:

• Vitamin C (ascorbic acid) – to accelerate development and enhance contrast

• Sodium carbonate (washing soda) – to create the alkaline environment needed for development

Why Use Rosemary as a Photographic Developer?

Rosemary (Rosmarinus officinalis) contains a powerful antioxidant known as rosmarinic acid, alongside other phenolic compounds such as caffeic acid. These naturally occurring chemicals act as reducing agents, meaning they can convert exposed silver halides into visible metallic silver—just like synthetic developers.

Rosemary works similarly to coffee-based developers (caffenol), but offers a distinct chemical profile, aesthetic tone, and an aromatic quality to the process.

How to Make a Rosemary Developer for Darkroom Printing

Here is a basic recipe tailored for developing photographic paper.

Ingredients:

• A bunch of fresh rosemary

• 500 ml distilled water

• 5 g ascorbic acid (vitamin C powder)

• 20–30 g sodium carbonate (washing soda)

Method:

1. Infuse the rosemarySimmer the rosemary in water for 30 minutes up to 1 hour to extract the rosmarinic acid. The water will turn a deep greenish-brown.

2. Cool and strainLet the infusion cool to room temperature and filter it through cheesecloth or a fine sieve.

3. Mix the developer

• Stir in the ascorbic acid until fully dissolved

• Add sodium carbonate to raise the pH and activate the developing properties

4. Test and adjustYou may experiment with concentrations, but this base is generally strong enough for fiber-based papers exposed under an enlarger.

How Rosemary Developer Works (Darkroom Chemistry Explained)

In conventional developers, substances like hydroquinone or metol donate electrons to exposed silver ions (Ag⁺) in the emulsion, reducing them to metallic silver (Ag⁰).

In a rosemary-based developer:

• Rosmarinic acid and caffeic acid act as electron donors

• Ascorbic acid boosts reducing power and helps maintain image density

• Sodium carbonate increases alkalinity, enabling the reduction process

  
  

Development Times: Traditional vs Sustainable Developers

This reaction is significantly slower than with synthetic developers:

Traditional paper developer:

Image appears in 15–30 seconds, full development in 1.5–3 minutes

Rosemary developer:

Image appears in 3–5 minutes, full development in 15–30 minutes

Results and Challenges of Rosemary Developer

The image on the right shows a darkroom print developed with rosemary developer, it produces softer, more muted tones compared to traditional developers. It offers however a unique aesthetic and aromatic quality, but it requires consistent agitation to avoid uneven development. It's normal that results vary between batches, and after exposing 5/7 prints, the developing solution gets weaker and dev time increases.

Sustainable Darkroom Practices: A Shift in Photography

Sustainable developers like rosemary-based formulas represent an important shift in photographic practice. They allow artists to rethink material choices, reduce toxicity, and explore new visual outcomes while maintaining a connection to historical processes.