Daguerreotype: The First Practical Photographic Process (1839)

Hold a daguerreotype under a light and the image disappears. Tilt it slightly and it comes back, reversed, floating on the surface of a polished silver plate like a hologram. There is no negative. There is no paper. There is no second copy. Each daguerreotype is a one-of-a-kind image on a copper plate clad with silver, and the image is made of nanoparticles of silver and mercury amalgam that scatter light depending on the angle you view them from. It is the earliest commercially successful photograph, announced in Paris in 1839, and its resolution and dynamic range remain impressive even by the standards of modern digital sensors.

The daguerreotype is a photographic process invented by Louis-Jacques-Mande Daguerre (1787-1851) and publicly announced to the French Academy of Sciences on August 19, 1839. A silver-coated copper plate is sensitized with iodine fumes to form silver iodide, exposed in a camera, developed with mercury vapor, and fixed with sodium thiosulfate. The result is a direct positive image on the plate itself, with no negative and no possibility of reproduction. Each daguerreotype is unique.

This entry covers how the daguerreotype works, its invention and history, the practitioners who defined it, and what modern conservation science has revealed about these 19th-century objects.

What Is a Daguerreotype and How Does It Work?

The process involves several steps. First, a copper plate is clad with a thin layer of silver. The silver surface is polished to a mirror finish, then sensitized by exposing it to iodine fumes in a sealed box, converting the silver surface to silver iodide, which is light-sensitive. The plate is loaded into a camera and exposed. Early daguerreotypes required exposures of several minutes, but improvements in lens design and chemical sensitization reduced this to seconds by the 1840s.

After exposure, the plate is developed by placing it in a heated chamber with mercury vapor. The mercury adheres to the exposed silver iodide, forming a silver-mercury amalgam. The unexposed silver iodide is then dissolved away with sodium thiosulfate, leaving a direct positive image. The image consists of nanoparticles of silver-mercury amalgam, including phases like schachnerite and gamma-phase Ag3Hg4, scattered across the polished silver surface. The particles scatter light differently depending on their density, which is why the image appears as a positive when viewed at one angle and a negative at another.

A 2019 study published in Proceedings of the National Academy of Sciences analyzed the plasmonic properties of daguerreotypes, identifying them as an early example of plasmonic color printing. The nanoparticles on the plate surface interact with light through plasmon resonance, the same physical mechanism that produces color in stained glass and butterfly wings. Read the study at PNAS.

Origins and History

The daguerreotype was not born from nothing. Louis Daguerre was a panorama painter and the inventor of the diorama, a theatrical spectacle that used painted scenes and changing lighting effects. He partnered with Joseph Nicephore Niepce, who had been experimenting with photographic processes since the 1810s. Niepce produced the first permanently fixed photographic image in 1822 using bitumen of Judea on a metal plate, a process he called heliography. Niepce died in 1833, and Daguerre continued the work alone, refining the process into what he would call the daguerreotype.

The French government purchased the rights to the process and made it freely available to the public in August 1839, with the exception of England, where Daguerre had patented it. Within months, daguerreotype studios opened across Europe and North America. By the mid-1850s, up to 3 million daguerreotypes were produced annually. The process dominated commercial portraiture for roughly two decades before being replaced by the collodion wet plate process, which was faster, cheaper, and reproducible.

A 2025 article published in Il Colle di Galileo traced the history of daguerreotypy through the network of scientists, primarily physicists and chemists, whose interest in light contributed to the advancement of photographic techniques. Read the study at Firenze University Press.

Key Practitioners

Louis-Jacques-Mande Daguerre (1787-1851)

Daguerre is the inventor. His Boulevard du Temple (1838) is one of the earliest surviving daguerreotypes. It shows a Paris street that appears empty because the long exposure, likely more than ten minutes, erased all moving traffic and pedestrians. One man remains visible: a customer having his boots shined, who stayed still long enough to register on the plate. It is often cited as the first photograph of a human being.

Carl August Steinheil (1801-1870)

Steinheil was a German physicist who produced some of the earliest daguerreotypes outside France. On September 5, 1839, only weeks after the Paris announcement, he exhibited two daguerreotypes in Munich. The Deutsches Museum holds 47 of Steinheil's plates, dated approximately 1839 to 1841. A 2023 study analyzed Steinheil's plates using X-ray fluorescence and infrared spectroscopy, revealing that he experimented with electrolytic gold and copper plating to protect and tint his images, an alternative to the chemical gilding introduced by Hippolyte Fizeau in 1840. Read the study at Technical University of Munich.

Antoine Francois-Jean Claudet (1797-1867)

Claudet was a French photographer working in London who obtained a license from Daguerre and became one of the most successful daguerreotype portraitists in England. He experimented with reducing exposure times and developed techniques for coloring daguerreotypes by applying pigments directly to the plate surface.

Robert Cornelius (1809-1893)

Cornelius was an American photographer who produced what is considered one of the first photographic self-portraits in 1839. He set up his camera in the yard behind his family's lamp store in Philadelphia, removed the lens cap, sat in front of the camera for several minutes, and replaced the cap. The resulting daguerreotype is in the Library of Congress.

Conservation and Modern Research

Daguerreotypes are fragile. The image sits on the surface of the plate with no protective coating, and the silver is vulnerable to tarnishing from sulfur compounds, chlorine, and moisture in the air. A 2025 study published in Talanta used reflectance imaging spectroscopy, micro-X-ray fluorescence, and macro-X-ray diffraction to recover images from degraded daguerreotype plates and map the distribution of corrosion products like copper formates and oxides. Read the study at Talanta.

Another 2025 study published in the Journal of Cultural Heritage developed a methodology for restoring degraded daguerreotypes using UV lasers and atmospheric non-thermal plasma cleaning techniques, offering conservators new tools for removing tarnish without damaging the image particles beneath. Read the study at Journal of Cultural Heritage.

Related Terms

The daguerreotype was contemporaneous with the calotype, William Henry Fox Talbot's paper negative process, which offered reproducibility where the daguerreotype offered unique images. It was eventually replaced by the wet plate collodion process and later by silver gelatin printing. The daguerreotype is also related to the cyanotype, another early photographic process invented by John Herschel. For more on the broader history of photography, read our post on photography as fine art, or explore our guide to portrait photography as art.

See Daguerreotypes in Person

Daguerreotypes must be seen in person to be understood. Reproductions flatten the mirror-like surface and eliminate the viewing-angle dependence that defines the medium. The Metropolitan Museum of Art in New York has an extensive collection of American and European daguerreotypes. The Musee d'Orsay in Paris holds Daguerre's original plates. The National Museum of American History at the Smithsonian has Cornelius's self-portrait.

When you look at a daguerreotype, tilt it back and forth. Watch the image shift between positive and negative. That shift is the signature of the process, and it is something no other photographic medium produces. For more on the broader context of early photography, read our entries on calotype and cyanotype, or explore our post on Ansel Adams and the evolution of photographic control.