A lumen print is made with a regular sheet of light sensitive b+w photo paper, an organic subject, such as a flower or a plant, a contact frame and a lot of sunshine for the light, but also for the heat. Once flattened and pressed between the glass and the paper, the plant natural pigments will transfer onto the silver halides leaving the water behind. The colors given depend on the type of plant, emulsion and exposure time. The stronger the sunlight the brighter the colors, whether the emulsion is warm or cold.