Lumen Prints – Easy, Quick and Colorful!

Lovely Lumen Prints! This colorful photogram was made using black-and-white darkroom paper in full sun.

Every year or so I try out a new photo process or technique.  It keeps me from getting into a rut, even if I don’t use it long-term.  It often stems from my continual search for new ways to spark my students’ interest in photography as more than a way to document what you had for lunch to post on Facebook (although a lesson in still-life using lunches was fun for the day!)  Last year’s how-to-teach-darkroom-work-without-a-darkroom experiment was anthotypes, which I am now loving.  This year’s experiment is Lumen Printing.

Remember those lovely blue prints you made as a kid by squashing weeds on top of a piece of blue paper in the sun, waiting a minute, then watching it reverse in water (called cyanotypes, if you want to get technical)?  Lumen prints work much the same way, but with regular darkroom paper and a single chemical bath that can also be done in full light.  The key difference in the prints are that they have better detail and can be made in a variety of colors.

Lumen prints are made by placing a flat object over a piece of black-and-white darkroom paper in a contact printer (or between a piece of plexiglas and a piece of sturdy cardboard, held together with clothespins) and left in the sun until it changes color, in as little as a few minutes in bright sun for a light-colored print.  The paper will change color in the sunlight, leaving the shadowed areas unchanged or less-unchanged.  Once exposed, the print is placed in a bath of print fixer for five minutes and it changes color again, but becomes more or less permanent.

The color you get depends largely on the brand of paper you use and the length of time the paper is out in the sun.  In a few weeks’ experimenting I’ve come up with pinks, browns, purple-ish gray, and golden prints from a variety brands of old, exposed stock and fresh papers.  The longer the paper is exposed to the sun, the deeper the darker the color.

reactions between plant and paper can create some interesting color shifts.

Where it gets really interesting is when one uses plant material.  Some plants will react with the paper, creating even more color variation, especially if the plant is starting to rot in the contact printer.  The image to the right was done on the one 80-degree, record-high day we had in April.  The fresh flowers were anything but fresh after awhile under glass in the hot sun.  Below are the results of using some herbs from the fridge that were past their prime.  These two only took about 20 minutes each.

Color shift due to rotting material reacting with the paper. Note that the fresh flower on the left did not react. This print was in the sun for about 20 minutes before fixing.

One of the great things about this technique is that the paper does not have to be fresh.  The packaged blue paper, often called blueprint paper or nature-print paper, has a shelf life of about six months before it starts yielding lighter and lighter prints.  Lumen prints, however, are a great way to use old, fogged papers that are no longer any good for regular darkroom printing.  And, as there are still people with darkrooms gathering cobwebs because they don’t know what to do with the stuff after they go digital, old paper can be had for free if you look around.

So, dust off that fogged paper from the back of your local darkroom shelf and try something new!


About heather

A third-generation, informally trained photographer, Heather Siple has been taking pictures since she was old enough to hold a point-and-shoot steady. Her work has appeared across the US and internationally in museums, galleries and publications. Siple is the founder of the photo group ArtLane PCG .
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