The chlorophyll process

The chlorophyll process is an organic alternative photography process akin to the anthotype process. However, instead of printing on the crushed extract of fruit or plant matter, the prints are bleached by sunlight directly onto the surface of leaves using a positive. Tiffany Pereira shares her experience with this process.

Writer / Tiffany Pereira
Photography / Tiffany Pereira and Binh Danh

Sunlight, Water and Leaves: Using the pigments of the life-giving photosynthesis process to develop images

­­­­­­The chlorophyll process is an organic alternative photography process akin to the anthotype process. However, instead of printing on the crushed extract of fruit or plant matter, the prints are bleached by sunlight directly onto the surface of leaves using a positive. The resulting images are stunningly delicate and beautiful, ranging from haunting silhouettes to crisp definition. Despite the simplicity of the finished product, the process itself can be tedious with plenty of trial and error.

But, to those who are willing to experiment with varying sunlight, exposure times and different leaf specimens it can be a fulfilling and humbling way to engage the natural world as part of your craft.

History of the chlorophyll process

British artists, Heather Ackroyd and Dan Harvey were among the first to define the Chlorophyll Process, though, in a slightly different format. They developed a method of projecting an image onto grass using a negative and light cast by a projector bulb after noticing vague outlines of a ladder cast onto one of their “grass installations”. The range of contrast of the negative denied or allowed light to reach certain areas of the grass surface resulting in the bleaching of the light deprived areas (see “The Science of Beaching” section below).

While effective, the grass bleaching process is complicated due to space and setup needs. Building on this concept, Artist Binh Danh took the Chlorophyll Process on a new path. Drawing on the Anthotype Process, Danh refined a method for securing a positive directly to a live leaf and allowing sunlight to bleach the image onto its surface naturally. He has also addressed a fundamental challenge with natural photography processes; that of fixing the image to prevent further bleaching and deterioration over time. To save his work, Dah casts his finished pieces in a layer of resin allowing them to be enjoyed for years to come.

The Science of Bleaching

When it comes to the Chlorophyll Process, and even the Anthotype Process in this case, having an understanding of the mechanisms behind the method can not only produce better results, but can also ease the learning curve for beginners.

We can understand how light bleaches an object at the atomic level. Pigments can be bleached by the colors of its compliment. When light hits an atom, electrons absorb energy of specific wavelengths exciting them to a higher energy state. The atoms quickly fall back down to the previous state, emitting a photon of light equal to that being absorbed, resulting in the observed color we see.

Bleaching occurs when a photon has enough energy to completely free an electron form its atom, becoming an ion with a net positive charge. Higher light intensity equals a higher concentration of ions, resulting in a surface which has the ability to react with the oxygen in the air. This reaction causes the bleaching of the surface.

Getting Started – What You’ll Need

• Leaves of your choice (broader and flatter are easier to work with)
• Positive / transparency (higher contrast preferred)
• Contact printing frame / sheets of glass
• Scissors / gardening stem cutter
• Newsprint / blotting paper
• Optional – You will need a way to provide the leaf with water if you want an even longer exposure. Small plastic bags and rubber bands work if you tie them around the stem securely (I use florist stem water tubes).
• Optional – UV stabilized polyester resin to cast the finished piece (Binh Danh’s recommendation http://www.tapplastics.com/product/fiberglass/polyester_resins/tap_surfboard_resin/38 )

The chlorophyll method

1Choose your leaf.
As noted, broader flatter leaves are easier to work with (spinach, maple or oak for example). This is a great way to engage your local environment, visit a park or your backyard! Think about how the leaf would add to your piece, either in composition or subject matter. Also, when cutting your sample, for transportation and preparation, cut the stem at an angle, leaving as much of the stem as possible, and immediately place the end in bag or bottle of water.

2Choose an image and create your positive/transparency.
Higher contrast of your positive with help with the overall clarity of your results though it is possible to achieve a wide spectrum of mid-tones.

3Arrange the positive on the leaf and sandwich both together in the contact printing frame or pressed tight between sheets of glass.
This is the tricky part of the process as you are dealing with a living organism. A contact frame works well as it presses the leaf flat for a solid and easy exposure. However, if you want to attempt to keep the leaf from drying out and dying for an even longer exposure, you’ll need to provide water. For this, I’ve found that pressing between glass sheets or a glass sheet and a masonite board works well. It is a more tedious set-up to fasten/tape the sheets together so the positive and leaf are as flat as possible, but you can position the leaf and positive so that the stem hangs out one side. This will allow you to secure a small bag of water to the stem tied tight with a rubber band. As noted, I use florist water tubes and periodically have to refill the water.

4Place in an area of direct sunlight.
As noted, sunlight intensity affects the rate of bleaching and the overall results. As a result, the time of year and geographic location will also have an impact on your prints.

5Checking and removing your print.
After at least 24 hours of direct sunlight, carefully check on your print to see if the bleaching process is occurring. As the leaf may have changed color overall due to drying, remember to let your eyes adjust to the color and texture of the leaf as chlorophyll print images can often be ghost like and vague. The leaf may also be thin, delicate and slightly moist. Thus, peel back the positive very slowly when removing it. Place the leaf in between newsprint or blotting paper to dry off.

6Preserving your Chlorophyll Print.
As this is a natural process, the sun’s bleaching power will continue to affect the leaf until it’s dry and brittle. From my experience, the image is not lost entirely over the years, but you do lose some of the crisp clarity. When not on display, press your leaf in a book to keep it flat and out of direct sunlight, remembering to use extreme caution when removing it for show. It is also possible to cast your leaf in a ¼ to ½ in layer of UV stabilized polyester resin (link above). Once the casting is completed, the print can be mounted and displayed without fear.

Special Thanks

• Special thanks to Binh Danh for his contributions to this article. All images used with permission from Tiffany Pereira and Binh Danh
• Special thanks to Xavier Fumat, for introducing me to alternative photography and being my faculty mentor at USC.
• Additional thanks to Binh Danh for taking the time to be a reference for this article. I appreciate your wisdom.

Tiffany Pereira is an Assistant Research Scientist, Ecologist and Scientific Illustrator with the Desert Research Institute in Las Vegas, Nevada. Her work focuses on the flora and fauna of the desert southwest. She is also interested in graphic design and illustration for science communication and education, having completed commissions for the Nevada State Museum, Las Vegas, publications, and private entities. Website: https://www.tiffanypereira.com/ Work: https://www.dri.edu/directory/tiffany-pereira/