collotype

1. A printing process employing a glass plate with a gelatin surface that carries the image to be reproduced. Also called photogelatin process.
2. A print made by this process.

1. Screenless lithographic printing process using continuous tone negatives; also called photogelatin. Collotype printing is not widely used but has been utilized for both fine art reproduction and low-quality color reproductions such as movie posters. The printing image is transferred from a metal or glass sheet covered by a gelatin-base substance.

2. Print made by using this process.

Collotype, a planographic photomechanical process and variant of photolithography, based on work by Poitevin in the 1850s, Joubert in 1860 (as ‘phototype’), and Albert (as ‘Albertype’) in 1868. A glass plate is coated with dichromated gelatin: exposure to daylight through a photographic negative selectively hardens the gelatin, while subsequent drying produces reticulations, resulting in tiny fissures that hold the ink and reproduce tonal gradation as a very fine irregular structure of wavy lines. Collotype was widely used for good-quality reproduction until the improvement of half-tone printing in the 1890s, and persists today for some limited-edition prints.

— Hope Kingsley

The noun has one meaning:

Meaning #1: a kind of color printing, used for the finest facsimile reproductions of works of art
  Synonyms: collotype printing, photogelation process