This is a guest post by Sam Klotz, who developed the primary source set “Civil War Photographs: New Technologies and New Uses.” Sam is a graduate of Stanford University and worked with the Library’s education team as a Liljenquist Family Fellow.
When I was conducting research for the Library of Congress primary source set “Civil War Photographs: New Technologies and New Uses,” I learned way more about photographic technologies that were used before the Civil War than I could fit into the brief teacher’s guide. Here’s a bit of what I learned about the calotype and the daguerreotype.
Invented in 1839 in Paris by Louis-Jacques-Mandé Daguerre, the daguerreotype was a photograph printed on a copper plate coated with light sensitive chemicals before exposure. Because of its intense detail and attractive shiny surface, it achieved success as a cheaper alternative to oil painting for portraiture, even though to have a daguerreotype taken, the subject had to sit facing direct light for a minute or longer without blinking or moving.
Some people criticized daguerreotypes for metaphysical reasons. French writer Honore de Balzac believed that people were made up of layers of skin and each time one had a daguerreotype taken, that person lost a layer of skin and thus a piece of his or her essence. Relatively inefficient and expensive compared to technologies like the ambrotype or tintype, the daguerreotype eventually went out of fashion later in the 19th century.
The calotype was the first ever negative-to-positive image process: a piece of paper bathed in chemicals so that it became light sensitive was placed inside the camera, which recorded a negative image on the paper upon exposure to light. These calotype negatives were then printed in positive on salted paper, a paper made light sensitive by being bathed in a chemical solution. Calotypes and salted paper were invented in England by William Henry Fox Talbot in the 1840s and were recognizable for their soft texture and lack of detail, instead emphasizing tone.
Calotypes never caught on in the United States, as the American public preferred the shine and detail of the daguerreotype, brought to the United States by Samuel Morse, over the soft tones of the calotype. By the 1860s, calotypes were largely out of use because of the development of the wet-plate/collodion process.
However, despite their lack of longevity, both calotypes and daguerreotypes are extremely important processes in the history of the photographic medium. The daguerreotype was the first mode of photography ever invented, while the calotype was the first negative to positive photographic technology, providing the basis for photographic technologies still in use today.
For more examples of each, plus a teacher’s guide, visit the primary source set “Civil War Photographs: New Technologies and New Uses.” You might ask your students to discuss how the amount of time and effort required to create an image might affect what they decide to photograph. Let us know how they respond in the comments.