Lumen prints are a form of photogram (camera-less photograph) created by arranging objects on top of black and white photography paper and leaving it in the sun.

Exposing the photosensitive emulsion to ultraviolet light changes its color in surprising ways. Resulting hues vary depending on exposure length, weather, time of day, season, brand and/or type of paper and whether or not fixer is used.

Photography pioneer William Henry Fox Talbot discovered the process in the 1830’s. The most common use of the technique has been to record images of plants and other organic materials.

Creating lumen prints on the roof of my building.
UV waves are able to penetrate fog.