Collotype

Early collotype postcard; 1882 in Nuremberg, signed by J. B. Obernetter
Postcard of the "Alte Oper" in Frankfurt, about 1900.

Collotype is a gelatin-based photographic printing process invented by Alphonse Poitevin in 1855 to print images in a wide variety of tones without the need for halftone screens. The majority of collotypes were produced between the 1870s and 1920s. It was the first form of photolithography.

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