Museum no. E.3195-1990
This image is an example of the photogravure technique. Photogravure, also known as heliogravure, is arguably the finest photomechanical means for reproducing a photograph in large editions. Gordon Baldwin, 'Looking at Photographs', J. Paul Getty Museum, 1991
Photogravure was devised by the Austrian printer Karel Klic (1841-1926) in 1879 and further developed by him.
The photogravure can be distinguished from other photomechanical printing processes by the lack of any regular or well defined structure, which can be seen in the subtle gradation of tones in this image.
The photogravure process depends on the principle that bichromated gelatin hardens in proportion to its exposure to light. A tissue coated on one side with gelatin sensitised with potassium bichromate was exposed to light under a transparent positive that had been contact printed from the negative of the image to be reproduced.
When wet, this tissue was firmly pressed, gelatin side down, onto a copper printing plate that had been prepared with a thin, even dusting of resinous powder. In warm water, the tissue-paper backing was peeled away and those areas of the gelatin that had not been exposed to light dissolved. The copper plate with its remaining unevenly distributed gelatin coating was then placed in an acid bath.
Where the gelatin remained thick (the highlights of the print to come) the acid ate away the metal slowly; where the gelatin was thin or absent, the acid bit faster. The plate was thus etched to different depths corresponding to the tones of the original image. When inked, the varying depths held different amounts of ink. The inked plate was then used in a printing press. Gordon Baldwin, 'Looking at Photographs', J. Paul Getty Museum, 1991
Alvin Langdon Coburn
This photograph can be found in Print Room Box 12.