Anthotype printing, a process also invented by Sir John Herschel in the 1840’s, uses botanical matter, or other natural light-sensitive compounds, to coat paper or other substrates. When the paper is exposed to sunlight, or other UV light sources, the light bleaches the color in areas of the paper not shielded, This process is extraordinarily labor intensive because most of the plant-based compounds bleach out very slowly, over hours, days, or sometimes even weeks. There is no way to fix the final print, so they can’t be exhibited in any normal fashion.