The evolution of the Carbon Print

102 Leadenhall Street, A. & J. Bool, 1878

The carbon print process was first developed by Frenchman, Alphonse Poitevin, in 1855. Poitevin is credited with being the first to develop the dichromate pigment process.  Although the process was discovered in 1855, it wasn't popularized until it was further developed and patented by Sir Joseph Wilson Swan, an English chemist and physicist, in 1864. Carbon prints are notable advancements in photography for the clarity and rich tones the prints achieve. In addition to the quality of the image, carbon prints do not fade or yellow the way the popular albumin prints did. The clarity and deep tones of the prints made it an ideal medium for reproducing fine art prints and reached peak popularity between 1870 and 1900¹.

                           

 The carbon process is different from other earlier methods, it suspends pigment in a gelatin base on paper or “tissue” which is then sensitized with a dichromate solution. The dichromate makes the gelatin insoluble where exposed to light and the remaining soluble gelatin washes away leaving the image². Because it is a pigment based process, the pigments can be changed from the original carbon black to other tones, mostly sepia and dark greens, and allow the images to take on other hues. Even before Swan patented the process, Louis Arthur Ducos du Hauron, a Frenchmen, is credited with introducing the use of other pigments. Carbon black was the first and most popular pigment used, hence the name of the process.

French street scene, Gabriel Cromer, 1919

The use of pigment is also critical the permanence of the image. Carbon prints are very stable, and as already mentioned, are not prone to fading. Stability of photographic images was a strong factor in the development of the carbon process because earlier and contemporary silver based processes of the 19^th century were highly prone to fading, and other forms of deterioration. Carbon prints can easily remain stable for hundreds of years if properly kept. 

 

--> Miss Isabella Bateman, Julia Margaret Cameron, not dated

Use of this method phased out almost completely by the mid 20^th century due to the highly labor intensive process, but this did not mean the end of the carbon print. Modern scientists are still working on the development of this photographic process. The historic process of carbon printing uses a dichromate as a sensitizer. Dichromate is now classified as a carcinogen and needs to be treated as hazardous waste. Experiments to substitute this chemical are still being conducted today. An experiment as outline in article, “On ammonium ferric citrate as sensitiser for carbon printing³,” explores replacing dichromate with ammonium ferric citrate as a means of using a more stable and non-toxic chemical in order to produce carbon images.  The beauty of the carbon print is so striking that even over a hundred years after it's invention it still inspires improvement. 

Sources:

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Bjørngård, H, and H Kobayashi. "On ammonium ferric citrate as sensitiser for carbon printing." Imaging Science Journal 58, no. 6 (2010): 301-307.

Ritzenthaler, Mary Lynn, Diane Vogt-O'Connor, and Mary Lynn Ritzenthaler. Photographs :Archival Care and Management. Chicago: Society of American Archivists (2006).

Romain, Louis F. "Carbro." PSA Journal 62, no. 1 (January 1996): 12.

http://www.alternativephotography.com/wp/processes/carbon-carbro/carbon-print-process

http://www.edinphoto.org.uk/1_early/1_early_photography_-_processes_-_carbon_print.htm

http://www.loc.gov/rr/print/coll/589_carbon.html

Footnotes:

1 http://www.loc.gov/rr/print/coll/589_carbon.html

2 http://www.edinphoto.org.uk/1_early/1_early_photography_-_processes_-_carbon_print.htm

3 Bjørngård, H, and H Kobayashi. 2010. "On ammonium ferric citrate as sensitiser for carbon printing." Imaging Science Journal 58, no. 6: 301-307. Academic Search Complete.