The autochrome was a "mosaic screen plate" that combined science with a surprising organic ingredient .

: The plate was loaded into a camera with the glass side facing the lens so light passed through the starch filters before hitting the light-sensitive emulsion .

: Approximately four million tiny grains of dyed potato starch per square inch were spread onto a glass plate .

: A special orange-yellow filter was required on the camera lens to correct the emulsion's natural over-sensitivity to blue light . Characteristics & Use Remembering Autochrome | Smithsonian Institution Archives

: Fine black soot filled the tiny spaces between the starch grains to prevent unfiltered light from washing out the image .