"Saving Our History Through Photographs"
This is the second of a series of technical leaflets that will be distributed by the ISU Special Collections Department through the ISU Extension Service. The Special Collections Department was founded in 1969, and collects papers, records, rare books, and other items that relate to Iowa State University, agriculture and rural life, and science and technology. As part of the Library’s mission, the Department would like to increase its outreach to the public about its work. These leaflets will cover a variety of topics, and are intended to assist Iowans in preserving their history by selecting and caring for papers, photographs and other items.
Leaflet #2 focuses on the history of photographs; the different types that will be in family collections; the best ways to care for photographs; and also provides a listing of archival suppliers and a bibliography.
History of Photographic Types
Daguerreotype (ca. 1837-1855): The daguerreotype, invented by Louis Daguerre and based on the work of F. Niepce, was the first practical photographic process. This "one-of-a-kind" photograph was produced on a thin layer of polished silver plated onto a copper plate. After being sensitized by chemicals, the plate was then exposed, and the image developed by a mercury vapor and fixed permanently by other chemicals. The extremely delicate image, which can appear as a positive or negative and can resemble a mirror when viewed, was then placed in a hinged case and covered with a brass mat and a sheet of glass. (The image itself should not be touched as it can be damaged easily.)
Ambrotype (1855-1860s): The ambrotype is also a "one-of-a kind" silver image in a collodion binder on glass. Collodion is a form of cellulose nitrate dissolved in ether and alcohol. The negative image produced is viewed as a positive image when the glass is backed by a dark material, such as paper, paint, or cloth. The ambrotype is usually placed in a case similar to the daguerreotype, but the image will appear as brown and milky white. Both daguerreotypes and ambrotypes will sometimes exhibit hand painted/tinted highlights and flesh tones.
Tintype or Ferrotype (1856-1920s): The tintype is also based on the collodion process, but the negative/positive image was placed on a sheet of lacquered iron. The metal sheet was painted dark brown or black, exposed, developed, fixed, and then varnished. The tintype was much cheaper and more durable than the earlier photographic processes, and was very popular. It was often encased in a paper holder or album, and the image is similar in tone to the ambrotype. The tintype was also occasionally hand tinted and the image is easily scratched.
Albumen Print (1850-1895): Albumen images consist of light sensitive silver salts in egg white on high quality paper. The photograph will have a purplish-brown hue and glossy surface, but commonly the egg white will have deteriorated giving the image an overall yellow tinge. Albumen paper prints are images made from negatives and were thus produced in the 19th century.
Carte-de-visites (1860s): were a common albumen print, a little larger than the size of a present day business card. The photographs are characterized by thin, square-cornered mounts, often with 2 gilt lines as a border. The sitter is either seated or standing, but is shown full length. "CDVs" were extremely popular and cheap, and thousands were printed daily.
Carte-de-visites (1870s): "CDVs" from the 1870s have thicker mounts and more elaborate ornamentation. The depiction of the sitter is usually closer-up.
Negatives (1840s-present): There was early English experimentation with paper negatives in the 1840s by Henry Fox Talbot, but due to restrictive patents, the concept did not immediately become popular in Europe or the U.S.
Collodion "wet plate" negatives (1851-1880): The collodion emulsion used in the creation of the ambrotype and tintype was also used to make glass plate negatives from which more than one print could be made. The exposure had to be made while the collodion was still wet, hence the name "wet plate." The negative image will appear as a milky brown, and there may be evidence in the corner that a hand clamp was used during the spreading of the collodion on the plate. Sometimes the glass will appear hand-cut.
Gelatin "dry plate" negatives (1880-1920): The more convenient method of dry plates replaced the wet plate negative. Gelatin, which could be exposed when dry, replaced collodion in the emulsion. The gelatin dry plate will appear uniform, and the glass will be machine cut.
Film-based negatives (1889-present): Photographers eventually began coating gelatin emulsions on plastics such as nitro-cellulose (nitrate film), cellulose acetate (safety film), and polyester. This led to the mass production of photographic film for home use and the motion picture industry.
Printing Out Papers (1890-1920): Gelatin and collodion printing out papers replaced albumen paper as the dominant print material in the 1890s. The images have an additional support layer and are a very glossy purple-brown color. Photographer also often toned their images (both printing out and developing) with metals such as gold and platinum. The most commonly encountered format is the studio portrait cabinet cards from the 1880s-1890s.
Cabinet Cards (1870s-1900s): Cabinet cards were larger than the cartes-de-visites with thicker mounts and rounded corners. The sizes ranged from 3 ¼ x 5 to 5 ¼ x 8 and larger. These cards were also usually marked with the name and address of the photographer.
Developing Out Papers (1885-present): One of the most important developments in the science of photography was the creation of a negative/print system that could be developed chemically at a later time than the actual exposure. The majority of developing out black and white prints from the early twentieth century are known as gelatin silver prints, as gelatin is used in the emulsion.
Color photographs consist of dyes (cyan, magenta, and yellow) residing in the gelatin emulsion on a photographic base such as paper or plastic. The color composition is determined by the concentration of the three dyes in the image. These dyes are susceptible to different rates of deterioration when exposed to light or stored in the dark.
Color prints (1942-present): The majority of color prints are chromogenic prints that have poor stability in light and dark storage. Its color development is "coupled" with the chemical reaction of a silver halide emulsion which is later bleached out—therefore, only the unstable color dyes are left. After 1969, all chromogenic color prints have included a polyethylene coated support that feels slippery. Examples from the 1970s have yellow staining around the edges.
Polaroids (1963-present): Fairly poor dye stability and an early tendency to curl required cardboard support for these one-of-a-kind images. (Note: there are also black and white Polaroids beginning in the 1940s).
Color negatives and transparencies (1905-present): Color negatives include Kodachrome which was reasonable dye stability when compared to Ektachrome, whose dyes will fade within a few years of processing.
For more information and suggested storage conditions for the preservation of color photographs, films, and slides, see The Permanence and Care of Color Photographs: Traditional and Digital Color Prints, Color Negatives, Slides, and Motion Pictures by Henry Wilhelm with Carol Brower (Grinnell, IA: Preservation Publishing Company, 1993).
Care and Handling of Photographs
DO handle negatives and photographs by their edges. It is a good idea to use cotton gloves. DO NOT let fingers touch the image surface. Oil on your fingers will adhere to the image.
DO keep working area and hands clean.
DO NOT use self-adhesive or magnetic photograph albums. DO NOT use scotch tape, glue, rubber bands, thumb tacks, glued-on photograph corners, or metal paper clips on photographs. All can cause irreversible damage.
DO use acid-free paper, acid-free photograph corners or pockets, or acetate sleeves to fasten photographs into albums or onto bulletin boards.
DO NOT display photographs in direct sunlight. Color photographs are particularly susceptible to fading and discoloration.
DO NOT label your photographs with a pen. Always use a soft-leaded pencil and write on the reverse of the image, along the margins. Identify photographs by who, where, and when.
DO NOT put glass directly on a photograph when it is framed. Use a mat of acid-free board to separate the photograph from the glass. Also use acid-free backing materials when framing photographs.
DO use care when photocopying photographs. DO NOT let photographs go through a feed copier.
DO store photographs in a sturdy box in a safe, dark, and dry place. DO NOT store photographs in the attic, garage, or basement.
Sources for Archival Supplies
Conservation Resources International
Applebaum, Barbara. Guide to environmental protection of collections. Madison, CT: Sound View Press, 1991.
Bennett, Mary. An Iowa album: a photographic history, 1860-1920. Iowa City: University of Iowa Press, 1990.
Conrat, Maisie. The American farm: a photographic history. San Francisco: California Historical Society, 1977.
Crawford, William. The keepers of the light: a history and working guide to early photographic processes. Dobbs Ferry, N.Y.: Morgan and Morgan, 1979.
Lesy, Michael. Bearing witness: a photographic chronicle of American life, 1860-1945. New York: Pantheon Books, 1982.
Reilly, James. Care and identification of 19th century photographic prints. Rochester: Eastman Kodak Company, 1986.
Rinhart, Floyd and Marion Rinhart. The American daguerreotype. Athens: University of Georgia Press, 1981.
Ritzenthaler, Mary Lynn, et al. Administration of photographic collections. SAA Basic Manual Series. Chicago: Society of American Archivists, 1993.
Wilhelm, Henry Gilmer with Carol Brower. The permanence and care of color photographs: traditional and digital color prints, color negatives, slides, and motion pictures. Grinnell, Iowa: Preservation Publishing Company, 1993.