Collotypes

Invented by the French chemist and photographer Alphonse Poitevin in 1855, the collotype was capable of rendering fine photographic detail with less work than other high quality photomechanical processes, making it suitable for duplicating photographs and works of art in forms such as postcards, posters, advertisements, and book illustrations.

Combining planographic and photographic technologies, images were printed using printing plates and ink, which could vary in colour but would often range from warm purple to cool, neutral tones. The process allowed for high-quality prints to be made from continuous-tone photographic negatives, without the need of halftone screens which instead break the image up into small dots when printing.