The science of light and shadow is fascinating, and wonderful to explore through historical forms of photography. Cyanotype, which is actually the oldest form of photography, utilizes iron salts and paper and results in a blue and white image. It was actually invented by an astronomer who wanted a way to ‘xerox’ his notes and sketches!
Students make a solargram using the sun to expose the paper – a technique used often by such surrealist icons as Man Ray. However, unlike silver-treated paper, cyanotypes can be developed without a darkroom, using water.
This project is both magical and educational for all ages. I like to take this further than the usual natural flora and fauna that people might use to create interesting silhouettes, adding on an exploration of how light travels through or is blocked by opaque, translucent and transparent objects, and what happens also when three-dimensional objects are added. During exposure, the direction from which the sun is coming also has an effect on the image; interesting shadows may appear and create a three-dimensional effect.
The examples below are of newly-developed, wet cyanotypes. When they dry, the evaporation process turns them a deep blue. Throughout the project, students get to see the paper change color multiple times. They learn the terms ‘positive’ and ‘negative’ and how that applies to photography and art in the larger sense: