Museum no. PH.354-1980
This image is an example of a platinum print.
The process for making platinum prints was invented in 1873 by William Willis (1841-1923), who continually refined it until 1878, when commercially prepared platinum papers became available through a company he founded.
Platinum prints are recognised by their subtle tonal variations and the permanence of the image. This print shows the silvery grey tones (the most usual colours of the platinum print) and the texture of the paper, which are typical qualities of a platinum print.
The process depends on the light sensitivity of iron salts. A dried sheet of paper, sensitised with a solution of potassium chloroplatinate and ferric oxalate, an iron salt, was contact printed under a negative in daylight (or another source of strong ultraviolet light) until a faint image was produced by the reaction of light with the iron salt.
The paper was developed by immersion in a solution of potassium oxalate that dissolved out the iron salts and reduced the chloroplatinate salt to platinum in those areas where the exposed iron salts had been. An image in platinum metal replaced one in iron. The paper was washed in a series of weak hydrochloric or citric acid baths to remove remaining excess iron salts and yellow stain formed in the earlier steps. Finally, the print was washed in water.
Platinum prints were popular until the 1920s when the price of platinum rose so steeply as to make them prohibitively expensive. They were partly replaced by the somewhat cheaper palladium prints. Gordon Baldwin, 'Looking at Photographs', J. Paul Getty Museum, 1991
This photograph can be found in Print Room Box 12.