A daguerreotype (original French: daguerréotype) is an early type of photograph, developed by Jacques Daguerre, in which the image is exposed directly onto a mirror-polished surface of silver bearing a coating of silver halide particles deposited by iodine vapor. In later developments bromine and chlorine vapors were also used, resulting in shorter exposure times. The daguerreotype is a negative image, but the mirrored surface of the metal plate reflects the image and makes it appear positive when the silvered surface has a dark ground reflected into it. Thus, daguerreotype is a direct photographic process without the capacity for duplication.

The daguerreotype was the first publicly announced photographic process and while there were competing processes at the time, the accepted scientific etiquette of the time was that discovery was attributed to first published. All of the initial photographic processes required long periods for successful exposure and proved difficult for portraiture. The daguerreotype did become the first commercially viable photographic process in that it was the first to permanently record and fix an image with exposure time compatible with portrait photography, but this was after extra sensitising agents (Bromine and Chlorine) were added to Daguerre's original process.

Invention

thumb|300px|Boulevard du Temple, Paris, 1838, by Daguerre. The first picture of a person. The image shows a busy street, but because exposure time was over ten minutes, the traffic was moving too much to appear. The exception is the man at the bottom left, who stood still getting his boots polished long enough to show.The daguerreotype is named after one of its inventors, French artist and chemist Louis J.M. Daguerre, who announced its perfection in 1839 after years of research and collaboration with Joseph Nicéphore Niépce, applying and extending the 1724 discovery by Johann Heinrich Schulze that a silver and chalk mixture darkens when exposed to light. The French Academy of Sciences announced the daguerreotype process on January 9 of that year. The announcement of the daguerreotype process in 1839, along with William Fox Talbot's later in the same year, marks the date used as the invention of photography.
Instead of Daguerre obtaining a French patent, the French government provided a pension for him. In Britain, Miles Berry, acting on Daguerre's behalf, obtained a patent for the daguerreotype process on August 14, 1839. Almost simultaneously, on August 19, 1839, the French government announced the invention as a gift "Free to the World."

Daguerreotype process

The daguerreotype, along with the Tintype, is a photographic image allowing no direct transfer of the image onto another light-sensitive medium, as opposed to glass plate or paper negatives. Preparation of the plate prior to image exposure resulted in the formation of a layer of photo-sensitive silver halide, and exposure to a scene or image through a focusing lens formed a latent image. The latent image was made visible, or "developed", by placing the exposed plate over a slightly heated (about 30°C / 90°F) cup of mercury. Daguerre was first to discover and publish (in the publication of the process and the English patent of 1839) the principle of latent image development.

The mercury vapour condensed on those places on the plate where the exposure light was most intense (highlights), and less so in darker areas of the image (shadows). This produced a picture in an amalgam, the mercury washing the silver out of the halides, solubilizing and amalgamating it into free silver particles which adhered to the exposed areas of the plate, leaving the unexposed silver halide ready to be removed by the fixing process. This resulted in the final unfixed image on the plate, which consisted of light and dark areas of grey amalgam on the plate. The developing box was constructed to allow inspection of the image through a yellow glass window to allow the photographer to determine when to stop development.

The next operation was to "fix" the photographic image permanently on the plate by dipping in a solution of hyposulphite of soda, often known as "fixer" or "hypo", to dissolve the unexposed halides. Initially Daguerre's solution to this step was to use a saturated salt solution but later adopted Hershel's suggestion of Sodium thiosulphate, as did WHF Talbot.

The image produced by this method is extremely fragile and susceptible to damage when handled. Practically all daguerreotypes are protected from accidental damage by a glass-fronted enclosure. It was discovered by experiment that treating the plate with heated gold chloride both tones and strengthens the image, although it remains quite delicate and requires a well-sealed enclosure to protect against touch as well as oxidation of the fine silver deposits forming the blacks in the image. The best-preserved daguerreotypes dating from the nineteenth century are sealed in robust glass cases evacuated of air and filled with a chemically inert gas, typically nitrogen.

Proliferation

André-Adolphe-Eugène Disdéri and Jules Itier in France, and Johann Baptist Isenring in Switzerland, became prominent daguerreotypists. In the United Kingdom, however, Richard Beard bought the British daguerreotype patent from Miles Berry in 1841 and closely controlled his investment, selling licenses throughout the country and prosecuting infringers. Among others, Antoine Claudet and Thomas Richard Williams produced daguerreotypes in the U.K.
Daguerreotype photography spread rapidly across the United States. In the early 1840s, the invention was introduced in a period of months to practitioners in the United States by Samuel Morse, inventor of the telegraph code. One of these original Morse Daguerreotype cameras is currently on display at the National Museum of American History, a branch of the Smithsonian, in Washington, DC. A flourishing market in portraiture sprang up, predominantly the work of itinerant practitioners who traveled from town to town. For the first time in history, people could obtain an exact likeness of themselves or their loved ones for a modest cost, making portrait photographs extremely popular with those of modest means. Notable U.S. daguerreotypists of the mid-1800s included James Presley Ball, Samuel BemisNewhall, Beaumont. The daguerreotype in America. 3rd rev. ed. New York: Dover Publications, 1976. ISBN 0486233227, Abraham Bogardus, Mathew Brady, Thomas Martin Easterly, Jeremiah Gurney, John Plumbe, Jr., Albert Southworth, Augustus Washington, Ezra Greenleaf Weld, and John Adams Whipple.

Ichiki Shirō's 1857 daguerreotype of Shimazu Nariakira, the earliest surviving Japanese photograph

This method spread to other parts of the world as well. In 1857, Ichiki Shirō created the first known Japanese photograph, a portrait of his daimyo Shimazu Nariakira. This photograph was designated an "Important Cultural Property" by the government of Japan.

The daguerreotype is commonly, erroneously, believed to have been the dominant photographic process into the late part of the 19th century in Europe. Evidence from the period proves it was only in widespread use for approximately a decade before being superseded by other processes:

• The calotype, introduced in 1841; a negative-positive process using a paper negative.

• The collodion wet plate process, introduced in 1851

a negative-positive process using silver salt impregnated collodion poured from a bottle onto a glass plate.
The collodion wet plate process was used to produce ambrotypes on glass and tintypes or ferrotypes on a coated iron plate.

• The ambrotype, introduced in 1854; a positive-appearing negative image on glass with a black paper backing.

• The tintype or ferrotype, introduced in 1856; a positive-appearing negative image on an opaque metal plate.

Demise

The intricate, complex, labor-intensive daguerreotype process itself helped contribute to the rapid move to the ambrotype and tintype. The proliferation of these simpler and much less expensive photographic processes made the very expensive daguerreotypes less appealing to the average person (although it remained very popular in astronomical observatories until the invention of glass plate cameras). According to Mace (1999), the rigidity of these images stems more from the seriousness of the activity than a long exposure time, which he says was actually only a few seconds (Early Photographs, p. 21). The daguerreotype's lack of a negative image from which multiple positive "prints" could be made was a limitation also shared by the tintype and was not a factor in the daguerreotype's demise until the introduction of the calotype. The fact that many of those to use the process suffered severe health problems or even death from mercury poisoning after inhaling the toxic vapors that were created during the heating process also contributed to its falling out of favor with photographers. Unlike film and paper photography however, a properly sealed daguerreotype can potentially last indefinitely.

Six daguerreotypes show a view of San Francisco, California in 1853.

In May 2007, an anonymous buyer paid 576,000 euros (~775,000 USD) for an original 1839 camera made by Susse Frères (Susse brothers), Paris, at an auction in Vienna, Austria, making it the world's oldest and most expensive commercial photographic apparatus.

The daguerreotype's popularity was not threatened until photography was used to make imitation daguerreotypes on glass positives called ambrotypes, meaning "imperishable picture" (Newhall, 107).

Value in the marketplace

Some daguerreotypes which have maker's marks, such as those by Southworth & Hawes of Boston, or George S. Cook of Charleston, South Carolina, Gurney, Pratt and others, are considered masterpieces in the art of photography. A daguerreotype of Edgar Allan Poe was featured on the PBS show Antiques Roadshow and appraised at US $30,000 to $50,000.

Living art

Daguerreotypy continues to be practiced by enthusiastic photographers to this day, although in much smaller numbers; there are thought to be fewer than 100 worldwide (see list of artists on cdags.org in links below). Its appeal lies in the "magic mirror" effect of light reflected from the polished silver plate through the perfectly sharp silver image and in the sense of achievement derived from the dedication and hand-crafting required to make a daguerreotype.

Footnotes