Platinum and Palladium Prints

"The First Frost" from "Life and Landscape on the Norfolk Broads" by Peter Henry Emerson, c. 1885.  Hosted by MoMA.

The photosensitive properties of platinum salts were first reported by Ferdinand Gehlen in 1830.  Over the following decades, a number of researchers experimented with the interaction of light and platinum salts in combination with other chemicals, both in solution and on paper; among them were Dobereiner, Herschel, and Hunt.  The early researches did not find a reliable way to fix a platinum-based image, in part because the easiest platinum salt to obtain (platinum chloride) is not easily reduced to metallic platinum.  In the 1850s, formulas for using platinum salts for toning of initially silver-based images were developed by a number of researchers, and the resulting platinum-toned images were found to be more resistant to fading than un-toned silver images.   By 1859, C.J. Burnett had produced palladium or possibly platinum prints using sodium chloroplatinate as a fixing agent.

"Woman with Lily", Eva Watson-Schutze, c. 1903.  Hosted by George Eastman House.

The first patent for a platinotype process was given to William Willis in 1873, but the process that eventually became commercially used was patented by him in 1880.  This process is known as the "hot bath" method; the paper is coated with a mixture of ferric oxalate and potassium chloroplatinate, exposed in direct contact with a negative, and then developed with a solution of warm potassium oxalate.  Other variants on the process have been, and still are, used, including printing-out papers as well as the developing-out process described above.  Palladium has very similar chemical properties to platinum, and has been used more or less interchangeably with platinum in the photographic process, depending largely on the relative costs of the two metals at a given time.

Platinum prints are, like salted paper prints, made on uncoated paper without baryta or emulsion layer, the photosensitive components being absorbed into the surface fibers of the paper.  Willis did attempt a process involving a gelatin-silver emulsion treated with platinum salts after exposure, but found that the platinum's effects on the gelatin itself made the results inconsistent.

"Printing: Foot and Steam Power" by Frances Benjamin Johnston, 1899-1900.  Hosted by MoMA

Commercial platinum photographic papers were available  from the 1880s to the 1930s; some artists willing to prepare their own papers have been doing platinum and palladium prints on their own since then, and from 1988 to 1999, the Palladio company offered a machine-coated palladium/platinum paper.  Platinum and palladium prints are extremely fade-resistant, and allow for very fine gradations of mid-tones.  These properties have appealed to art photographers since the process first became available.  Because the platinum and palladium salts are not sensitive to the lower-frequency end of the visual spectrum, the papers can be prepared, exposed, and developed without a true dark-room, using lower-intensity indoor lighting when working with the sensitized paper and using either sunlight or an ultraviolet light-box to expose the paper through the full-sized negative.  This property has made platinum and palladium prints appealing to artists who want to experiment with developing their own prints.

Video of the process of palladium print making by Giorgio Bordin


Video of the process of platinum/palladium print making by Simone Casetta, narrated in Italian with English subtitles
 


Platinum and palladium prints can be identified by their generally matte appearance; the visibility of paper fibers under magnification; their un-faded appearance, with fairly saturated blacks and a wide range of mid-tones; and, if they are mounted in a folder or album, the orangeish mirroring of the image on the facing page owing to the image material catalysing the breakdown of the paper.  Prints done on hand-prepared paper also tend to have dark brush-marks surrounding the image area; machine-made commercial platinum papers would not have this feature.  Palladium prints tend to have a somewhat warmer color tone than platinum, but the difference is subtle and the metals have often been used in combination.

Sources:

Hafey, John and Shillea, Tom.  The Platinum Print.  Graphic Arts Research Center, Rochester Institute of Technology, 1979.  Web.  February 27, 2013.  <http://www.kimeia.com/pdf/history.pdf>

"Platinum Print".  Wikipedia.  Wikimedia Foundation, 2013.  Web.  February 27, 2013.  <http://en.wikipedia.org/wiki/Platinum_print>

Ware, Mike.  "The Eighth Metal: the Rise of the Platinotype Process".  Photography 1900: The Edinburgh Symposium.  National Museums of Scotland and National Galleries of Scotland, 1993.  Web.  February 27, 2013.  <http://www.mikeware.co.uk/mikeware/Eighth_Metal.html>