Lumen Prints

Overview

Lumen printing is a camera-less photographic process that uses expired or outdated black-and-white photographic paper exposed directly to sunlight. Objects placed on the paper block light, creating photograms with unique colours and tones that emerge from the paper's degraded silver halides.

How It Works

Unlike traditional darkroom printing where paper is exposed briefly and then developed, lumen prints are exposed for extended periods (hours) in direct sunlight without chemical development. The image forms through direct photochemical action—a "printing out" process similar to historical techniques.

The colours that emerge—pinks, purples, browns, oranges—result from:

• The paper's age and storage conditions
• Organic material in contact with the emulsion
• Moisture levels during exposure
• Exposure duration and UV intensity

Materials

Paper

• Expired black-and-white photographic paper (the older, the better)
• Different brands/types produce different colour palettes
• Fibre-based paper often produces richer colours than RC
• Store paper improperly (warm, humid) to accelerate colour potential

Objects

Anything that blocks or filters light:

• Botanical materials (leaves, flowers, feathers)
• Translucent objects (glass, fabric)
• Found objects
• Negatives (for more traditional photographic images)

Contact Frame

• Glass-topped frame to hold objects flat
• Or simply glass and backing board with clips

Basic Process

1. Setup: In subdued light, place objects on photographic paper, emulsion side up.

2. Contact: Cover with glass to ensure firm contact.

3. Exposure: Place in direct sunlight for 2-8 hours (or longer for deeper colours).

4. Assessment: Check periodically—colours shift and develop over time.

5. Optional fixing: Fix in standard fixer to make permanent (colours will shift toward sepia/brown) or leave unfixed and scan immediately.

Fixing Considerations

Unfixed Prints

• Retain full colour range (pinks, purples, oranges)
• Will continue to change with light exposure
• Must be stored in complete darkness
• Scan or photograph immediately to preserve colours

Fixed Prints

• Fixing shifts colours dramatically—usually toward brown/sepia
• Removes most of the pink/purple tones
• Print becomes light-stable
• Traditional archival properties

Partial Fixing

Some practitioners briefly fix (30 seconds to 1 minute) for a compromise between colour retention and stability.

Colour Palette

Different papers and conditions produce different colours:

Common Colours

• Pinks/magentas: Often from fresh botanical material
• Purples: Extended exposure, certain paper types
• Oranges/browns: Very long exposures, fixed prints
• Yellows: Some paper types, certain plant materials

Advanced Techniques

Wet Lumen Prints

Placing botanical material on paper while wet intensifies chemical reactions between plant material and silver halides, often producing more vivid colours.

Toning Unfixed Prints

Brief toning (gold, selenium) before fixing can alter and preserve some colours.

Multiple Exposures

Moving objects during exposure or re-exposing with different objects creates layered imagery.

Combination with Other Processes

Some practitioners coat lumen prints with cyanotype or other emulsions for multi-layered work.

Technical Considerations

Exposure Time

• Minimum: 2-4 hours in bright sun
• Typical: 4-8 hours
• Extended: Days to weeks for maximum colour development

Season and Location

• Summer sun produces faster, more intense results
• Winter/overcast requires longer exposures
• Altitude and latitude affect UV intensity

Paper Selection

Experiment with different papers:

• Ilford Multigrade
• Kentmere
• Kodak Polycontrast
• Oriental
• Expired papers from any manufacturer

Each behaves differently. Build a collection of expired papers for varied results.

Documentation

Because unfixed lumen prints continue to change, many practitioners:

• Scan immediately after exposure at high resolution
• Photograph under controlled lighting
• Keep detailed notes on paper type, exposure, and conditions
• Accept that the physical print is ephemeral

Characteristics

• Camera-less (photogram technique)
• Unique colour palette impossible with conventional processes
• Each print is one-of-a-kind
• Meditative, slow process
• Environmentally connected (sun exposure, botanical subjects)
• Uses materials otherwise destined for disposal

Safety

Lumen printing is one of the safest photographic processes, requiring no hazardous chemicals for the basic process.

Tips for Success

1. Collect expired paper — ask at photo labs, buy cheaply online
2. Use fresh botanical material — it produces more colour than dried
3. Try wet processes — moisture intensifies colour reactions
4. Expose longer than you think — colours continue to develop
5. Scan before fixing — you can always fix later, but you can't unfix
6. Keep notes — with so many variables, records help you learn

Historical Context

While not a historical process per se, lumen printing connects to the earliest days of photography when images were "printed out" by direct light action rather than chemical development. It also echoes the photogram experiments of Man Ray and Moholy-Nagy, applying their camera-less approach to a medium that generates its own colour palette.

Further Reading

Christina Z. Anderson, The Experimental Darkroom (Routledge) Part of the Contemporary Practices series. Covers lumen printing alongside other experimental camera-less techniques.

Christopher James, The Book of Alternative Photographic Processes, 3rd Edition (Cengage Learning, 2015) The definitive comprehensive text on alternative processes, with coverage of contemporary camera-less techniques including lumen printing.

AlternativePhotography.com Extensive free articles on lumen printing, with galleries of contemporary practitioner work and practical tutorials.