What is photogravure etching?
A photogravure is a photographic image produced from an engraving plate.
Photogravure developed in 1850s. The process is rarely used today due to the costs involved, but it produces prints which have the subtlety of a photograph and the art quality of a lithograph.
How is the photogravure made?
Firstly, you need to take the picture and make a glass transparency from the negative.
Secondly, copper engraving plate is dusted with grains of bitumen and heated. When bitumen is attached to the plate, a carbon print is tranfered to the plate.
Thirdly, the unexposed gelatin of the carbon print is washed away with warm water.
Forthly, axcid is applied to the plate to eat away the softest gelatin. So the least light comes from the darkest areas.
Finally, ink is spread over the plate, which is then pressed onto the paper. The areas with most ink print darkest.
A photogravure looks like a photograph but is a series of connected lines, rather than unconnected dots as in a photograph.