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Twentieth Century Photography > Nineteenth Century Photographic Processes

Bases & Emulsions

Most photographs have a base and a light-sensitive emulsion. The base supports the emulsion. Bases can be many materials but usually are metal, glass, film or paper. Emulsions can be created from many materials and the light-sensitive materials they contain comprise different chemicals. Most emulsions are either albumen, collodion, or gelatin and the most common light-sensitive materials are silver salts.


Considered to be the first successful and practical photographic process, daguerreotypes were named for their inventor, J. L. M. Daguerre, in 1839. They were most popular between 1839 and the late 1850s with some dating into the 1860s. To create a daguerreotype, a copper plate (the base) was coated with silver and then cleaned and finely polished. This mirror-like polished plate was placed in a small box and exposed to iodine vapors for five to thirty minutes. The result was a film on the plate's surface composed of silver iodide (the emulsion). The sensitized plate was placed in a camera and exposed to light for five to seventy minutes. After 1840 the exposure time was reduced to between five and forty seconds due to improved lenses and more sensitive plates. The exposed plate was removed from the camera and placed in another box where it was exposed to the fumes of heated mercury. When the mercury vapors had brought out the image, the plate was removed, immersed in a solution of distilled water and common salt or hyposulphide of soda, and dried over a flame. By 1841, toning in a bath of gold chloride protected the emulsion, enhanced image contrast, and warmed the image's hue. Images were commonly colored by hand and placed under glass in cases.

Each daguerreotype is unique. It is a direct positive, laterally reversed image with no negative. Daguerreotypes were made in a variety of sizes from a whole plate (8 ½ x 6 ½ in.) to a sixteenth plate (1 3/8 x 1 5/8 in.) The most common sizes are quarter plates (3 1/4 x 4 1/4 in.) and sixth plates (2 3/4 x 3 1/4 in.).


First produced by James A. Cutting in 1854, ambrotypes were an application of the wet collodion emulsion process developed by Frederick Scott Archer in 1848. They were most popular in the mid 1850s, but were available between 1854 and 1881. To create an ambrotype a well-cleaned and polished plate of glass was sensitized by pouring collodion mixed with potassium iodide or bromide evenly over the surface. Collodion is a mixture of gun cotton (purified cotton with nitric and sulfuric acid), ether, and alcohol. The sensitized plate was then soaked in a silver nitrate solution, placed in a holder, underexposed in a camera, and developed while still wet. After development the plate was often bleached. Because a faint negative image was produced, the plate was backed by a black material such as cloth, paper, metal, varnish or paint. The black backing showed through mostly where the negative image was thinnest. Sometimes a dark purple, blue or red glass plate was used making it unnecessary to use a backing.

Each ambrotype is unique. It is a direct positive, non-laterally reversed image. Much cheaper than daguerreotypes, ambrotypes were cased and oftentimes mistakenly identified as daguerreotypes. To distinguish between the two, ambrotypes appear as positives at all angles of illumination while daguerreotypes appear positive only at certain angles.


Developed by Hamilton L. Smith in 1856, tintypes were another application of the wet collodion emulsion process developed by Frederick Scott Archer in 1848. They were popular mostly in the United States beginning just prior to the Civil War and continuing into the 20th century. To create a tintype, a thin sheet of iron lacquered in black or chocolate brown was sensitized by pouring collodion mixed with potassium bromide evenly over the surface. The sensitized iron sheet was then soaked in a silver nitrate solution, placed in a holder, exposed in a camera, and developed while still wet. Most tintypes were varnished to protect the surface and placed in paper mats. Many early examples were cased.

Each tintype is unique. When multiple identical images are found, they were probably made with a multi-lens camera. It is a direct positive, laterally reversed image. More durable and less expensive than daguerreotypes and ambrotypes, tintypes (or more properly, ferrotypes) were frequently mailed to friends and relatives. They were made in a great variety of sizes but the most common format was 2 ½ x 3 ½ in.

Albumen Prints & Wet Plate Collodion Negatives

In order to understand the production of albumen prints, which were often mounted on different sized card stock and generically called card photographs, one must understand the production of wet collodion negatives. The major mode of photography shifted from direct positives (daguerreotypes, ambrotypes, and tintypes) to the negative/positive process using wet collodion negatives and albumen prints when the collodion negative came into extensive use by 1860 and into the 1880s.

A glass plate was coated with a thin layer of liquid collodion mixed with a dissolved iodide or bromide salt. After the coating set, the plate was immersed in a solution of silver nitrate thus forming silver iodide or silver bromide in the collodion pores. All before the plate dried out within five to fifteen minutes, the photographer exposed the plate in the camera, developed it with pyrogallic acid, and fixed the image with potassium cyanide or sodium thiosulphate (hypo).

According to photo historian, James Reilly, albumen prints from wet collodion negatives comprise approximately 80 percent of the extant prints in nineteenth-century historical collections in the United States. Albumen (egg whites) was beaten and mixed with sodium or ammonium chloride to create the emulsion which was applied by flotation to the very thin base paper. Stored until it was time to use, the paper was then sensitized by flotation on a solution of silver nitrate and acetic acid. After drying, the sensitized paper was placed in contact with the negative and exposed in a printing frame in the sun until the image appeared. It was then washed in water, toned with gold chloride, fixed with hypo, and given a final wash. The toning gave the image a rich purple-brown color. Trimmed to the edge to minimize the expense of gold toner, the very thin albumen prints were susceptible to tearing or curling. Consequently, the prints were mounted on cards, either of standard commercial size or a size to accommodate the photographer's format.

Card Photographs

Card photographs were the most popular way to present nineteenth-century photography. Prints of many different types of processes were mounted on various sized cards. They include cartes de visite, cabinet cards, and stereographs. Often having printed information about the photographer or studio that is useful for dating and identifying images, card photographs might also exhibit captions and identifying information by their owners.

Cartes de Visite & Cabinet Cards

Introduced in the United States in 1859 and made into the 1900s, the carte de visite (CDV) was a popular format on which to present albumen prints. A special camera with four, eight, or more lenses was used to make as many images as possible of a single or different poses on a single glass plate. A contact print was made and the individual photographs were mounted onto cards measuring 2 ½ x 4 1/4 in. When interest in the small portraits of the CDVs waned, studios produced photographs and cards in larger sizes: Cabinet, 4 ½ x 6 1/4 in.; Victoria, 3 1/4 x 5 in.; Promenade, 4 x 7 in.; Boudoir, 5 1/4 x 8 ½ in.; Imperial, 6 7/8 x 9 7/8 in.; Panel, 8 1/4 x 4 in. Cabinet photographs were introduced in the United States in 1866 and were popular to around 1900.


Daguerreotypes, ambrotypes, and albumen prints were among the many different processes used to produce stereographs. Stereographs were formed of two images placed side by side. The images were most commonly produced with cameras that had two lenses side by side, 2 ½ in. apart, and exposed simultaneously. The lenses were spaced to approximate the view a person would have with each eye receiving a slightly different image. Viewed through a stereoscope, stereographs, measuring 4 ½ x 7 in., created a three-dimensional effect. Paper prints from wet collodion negatives were the most convenient way of producing card stereographs (stereo cards). Stereographs were popular in the United States between 1859 and the 1920s.


Young boy with gun and powderhorn, circa 1890, Whitehurst, Daguerreotype, b&w, 3.25 x 3.75 in., Accesssion #: 2003.081, Photographic Study Collection


Ambrotype in case of leather work, circa 1860, Ambrotype, b&w, 3.25 x 3 1/8 in., Accession #: 2002.041, Photographic Study Collection.


Western frontiersman in buckskin costume with gun , circa 1890, Tintype, b&w, 6.5 x 4.25 in., Accession #: 2003.273, Photographic Study Collection


Civil War Town (possibly Bonsall photo), circa 1863, I.H. Bonsall, photographer, Wet collodion negative, b&w, 6.5 x 8.5 in., Accession #: 2000.005.5.33, Robert E. Cunningham Collection


Mountain man Seth Kinman in bear chair , circa 1875, Matthew B. Brady, photographer, Washington, D.C., Carte de visite, b&w, 3.5 x 2.25 in., Accession #: 2003.088, Photographic Study Collection


"A Dandy Shot, Jim, See Where the Bullet Blazed Him." Elk Hunt, Montana, U.S.A., 1903, Meadville, PA, Keystone View Company, Stereograph, b&w, 3.5x7 in., Accession #: 2004.317, Photographic Study Collection

Additional Reading:

Durrah, William C. The World of Stereographs. Gettysburg: W. C. Darrah, 1977.
Durrah, William C. Cartes de Visite in Ninteenth Century Photography. Gettysburg: W. C. Darrah, 1981.
Eaton, George T. Conservation of Photographs. Rochester: Eastman Kodak Company, 1985.
Thesaurus for Graphic Materials. Washington, D.C.: Library of Congress, 1995.
Mace, O. Henry. Collector's Guide to Early Photographs. Iola: Krause Publications, 1999.
Reilly, James M. Care and Identification of 19th-Century Photographic Prints. Rochester: Eastman Kodak Company, 1986.

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