The wet-plate collodion
by Frederick Scott
Archer in 1851, was the
method for making the
types of photographs
popular during the
American Civil War.
Early types of positive prints
In the 1840s and 1850s, as politicians in the
North and South hotly debated the issues
leading up to the Civil War, Americans were
introduced to the first popular type of photography: the daguerreotype.
Named for French inventor Louis
Daguerre, the daguerreotype’s substrate,
canvas or “film” was a silver-coated copper
plate exposed to iodine fumes, then placed in
the back of a camera and illuminated. When
subsequently exposed to the fumes from heated mercury, the
latent image would emerge as the silver would adhere to the
regions of the plate that were exposed to light. The result was
a unique, detailed positive print that could be seen only from
Daguerreotypes fascinated Americans of the mid-19th century, and many of the photographers who would later chronicle
the American Civil War got their start in the business making
them. In major cities, the public flocked to galleries to see portraits of famous people. In the 1850s, the expense and impracticality of daguerreotypes led to their replacement by new types of
photographic processes: the calotype, the ambrotype, the tintype
(also known as the ferrotype) and the albumen print.
The calotype process uses silver-salted paper to make a
paper negative. In theory, one could make a large number of
positive copies by contact-printing the
negatives onto other sheets of light-sen-
sitive paper. In practice, calotype prints
lacked some of the fine detail of daguerre-
otypes. Also, sometimes the texture of
the negative paper would leave unwanted
marks on the positive print.
Wet-plate collodion process
The wet-plate collodion process, invented by Frederick Scott
Archer in 1851, was the method for making the types of photographs popular during the American Civil War. The difference
was in the substrate: ambrotypes, as well as commercial portrait
and landscape prints, required glass-plate negatives, while
tintypes were printed on black-lacquered iron (not tin).
Library of Congress
Noncommissioned officers’ mess of Co. D, 93rd New York Infantry in Bealeton, Va.
Image is a digital scan of original wet collodion glass negative.
26 | OPN Optics & Photonics News