Cliché verre - Wikipedia
Glass plate printing.
A semiphotographic method of printmaking on glass first practiced in the 1830s, revived in the 20th century first by Klee and then others.
Cliché verre, also known as the glass print technique, is a type of "semiphotographic" printmaking.[1] An image is created by various means on a transparent surface, such as glass, thin paper or film, and then placed on light sensitive paper in a photographic darkroom, before exposing it to light. This acts as a photographic negative, with the parts of the image allowing light through printing on the paper. Any number of copies of the image can be made,[2] and the technique has the unique advantage in printmaking that the design can be reversed (printed as a mirror image) just by turning the plate over. However, the image loses some sharpness when it is printed with the plain side of the glass next to the paper.[3]