Chlorophyll Printing

What It Is

Chlorophyll printing exploits the photo-bleaching property of chlorophyll — the green pigment in plant leaves. When protected from light (under a negative), chlorophyll retains its colour. Where it receives direct UV light, it bleaches to pale yellow-white. The image forms as a contrast between the protected (green) and exposed (bleached) areas.

The process requires no chemistry — just sunlight, plant leaves, glass, and a negative (transparency film, photocopy on acetate, or printed inkjet transparency). It is one of the most accessible photographic processes available.

Why Artists Use It

Chlorophyll printing bridges botanical practice and photography. The image is made in the plant itself — not on paper or metal, but in a living material that was growing hours before the exposure. The resulting prints have a fragility and organic quality that no synthetic photographic material can replicate.

The process is inherently site-specific and seasonal: different plants, different UV levels, different seasons all produce different results. A chlorophyll print made in July with maximum UV intensity is different from one made in October. This responsiveness to place and time is part of the practice.

Plant Selection

From the San Casciano workshop (Almudena Romero, 2025):

• Best results: Leaves with uniform, dense chlorophyll. Thick, waxy, or oversized leaves often work well.
• Recommended species: Oleander (Nerium oleander), fig without fruit (Ficus carica), aspidistra (Aspidistra elatior), African pink / dianthus, money plant (Pachira aquatica), oxalis, Vietnamese ving dang (25-year plant)
• Shade-adapted vs sun-adapted: Shade-adapted plants (aspidistra, peace lily) tend to have more uniform chlorophyll and produce cleaner prints. Sun-adapted plants already show chlorophyll variation from natural UV exposure.
• Avoid: Variegated leaves (already lack uniform chlorophyll), very thin leaves (bleach too quickly), hairy or textured surfaces (prevent full contact with glass)

Process

1. Prepare the negative: Use a positive transparency (inkjet or laser on acetate) — dark areas block UV, light areas transmit. The image will appear as: dark areas = green (protected), light areas = bleached yellow-white.
2. Set up the contact frame: Place 2–3 meters of glass sheet (flat). Layer: glass → leaf → negative → glass. Full contact — no air gaps between leaf and negative. Air gaps cause soft, unsharp areas.
3. Expose: Place in full direct sunlight, UV index as high as possible. Exposure time: 2–3 days for standard results. Rotate or check periodically. If too hot: the plant exhausts its chlorophyll before a clear image forms — place in bright shade in extreme heat.
4. Check: Lift carefully to check progress without disturbing alignment. The bleached areas should be clearly pale yellow-white; the protected areas should remain vivid green.
5. Remove and preserve: Once the image is clear, remove the negative. Allow the leaf to dry slowly in a cool location.

Preservation

Chlorophyll prints are inherently unstable — the pigment will continue to bleach with light exposure over time. To slow this:

• UV-blocking acrylic glass (Plexiglass): Frame under UV-filtering glazing
• UV-resistant acrylic spray: Apply thin coat after drying
• Resin coating: A thin resin layer can stabilize the surface
• Copper sulfate: A traditional preservation treatment — the leaf is treated with copper sulfate powder in a UV-free, air-free environment for approximately 15 days. The copper bonds with the chlorophyll complex, stabilizing it against further light degradation.
• Store in the dark when not on display.

Tools & Safety

• Glass sheets (2–3mm, cut to size) — clean twice with sodium carbonate solution before use
• Contact printing frame or heavy books for weight
• Inkjet or laser printer + acetate transparency film for negatives
• UV-resistant fixer spray for preservation

No chemical hazards in the basic process. Copper sulfate preservation requires gloves and eye protection.

Common Failures

• Blurry image: Air gap between leaf and negative. Ensure full, uniform contact. Use flat, smooth leaves without raised veins in the image area.
• No bleaching (image doesn't appear): Insufficient UV. Move to more direct sunlight or higher UV period (summer, midday).
• Over-bleaching (full leaf turns yellow): Too much UV or too long exposure. Reduce time, or work in less intense light conditions.
• Leaf dries during exposure: Keep stems in water during the process if the leaf is still attached to the plant, or ensure the cutting is fresh and hydrated before laying flat.

Jay's Studio Note

The San Casciano workshop (Almudena Romero, Tuscany, 2025) introduced chlorophyll printing in the context of a four-day intensive spanning chlorophyll printing, anthotypes, cyanotype, lumen printing, and watergrams. The key lesson: the plant is not a passive surface — it participates. The way a specific aspidistra leaf from a specific garden in Tuscany responds to a specific UV index in September is unrepeatable. That specificity is the whole point. The resulting prints look like nothing else in photography: green, organic, fragile, already in the process of changing.

Related Entries

Cyanotype — another process from the San Casciano workshop · Botanical Embedding — botanical materials in bioplastic · Anthotype — plant pigment photography

References

• Almudena Romero — chlorophyll printing and cameraless photography workshop, San Casciano, Tuscany, 2025
• Vietnamese ving dang 25-year plant — workshop specimen