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Daguerreotype

Early photographic technique

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Portrait of Louis Daguerre (1787-1851)
Jean-Baptiste Sabatier-Blot · Public domain

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Invented by Louis Daguerre and introduced worldwide in 1839, the daguerreotype was almost completely superseded by 1856 with new, less expensive processes, such as the ambrotype (collodion process), that yield more readily viewable images. Since the late 20th century, some photographers interested in making artistic use of early photographic processes have revived the daguerreotype process.

To make the image, a daguerreotypist polished a sheet of silver-plated copper to a mirror finish; treated it with fumes that made its surface light-sensitive; exposed it in a camera for as long as was judged to be necessary, which could be as little as a few seconds for brightly sunlit subjects or much longer with less intense lighting; made the resulting latent image on it visible by fuming it with mercury vapor; removed its sensitivity to light by liquid chemical treatment; rinsed and dried it; and then sealed the easily marred result behind glass in a protective enclosure.

The image is on a mirror-like silver surface and will appear either positive or negative, depending on the angle at which it is viewed, how it is lit and whether a light or dark background is being reflected in the metal. The darkest areas of the image are simply bare silver; lighter areas have a microscopically fine light-scattering texture. The surface is very delicate, and even the lightest wiping can permanently scuff it. Some tarnish around the edges is normal.

Several types of antique photographs, most often ambrotypes and tintypes, but sometimes even old prints on paper, are commonly misidentified as daguerreotypes, especially if they are in the small, ornamented cases in which daguerreotypes made in the US and the UK were usually housed. The name "daguerreotype" correctly refers only to one very specific image type and medium, the product of a process that was in wide use only from the early 1840s to the late 1850s.

History

Since the Renaissance era, artists and inventors had searched for a mechanical method of capturing visual scenes. Using the camera obscura, artists would manually trace what they saw, or use the optical image as a basis for solving the problems of perspective and parallax, and deciding color values. A camera obscura optically reduces a real scene in three-dimensional space to a flat rendition in two dimensions.

In the early 17th century, the Italian physician and chemist Angelo Sala wrote that powdered silver nitrate was blackened by the sun, but did not find any practical application of the phenomenon.

The discovery and commercial availability of the halogens iodine, bromine and chlorine a few years earlier meant that silver photographic processes that rely on the reduction of silver iodide, silver bromide and silver chloride to metallic silver became feasible. The daguerreotype is one of these processes, but was not the first, as Niépce had experimented with paper silver chloride negatives while Wedgwood's experiments were with silver nitrate as were Schultze's stencils of letters. Hippolyte Bayard had been persuaded by François Arago to wait before making his paper process public.

Previous discoveries of photosensitive methods and substances—including silver nitrate by Albertus Magnus in the 13th century, a silver and chalk mixture by Johann Heinrich Schulze in 1724, and Joseph Niépce's bitumen-based heliography in 1822—contributed to development of the daguerreotype.

The first reliably documented attempt to capture the image formed in a camera obscura was made by Thomas Wedgwood as early as the 1790s, but according to an 1802 account of his work by Sir Humphry Davy:

The images formed by means of a camera obscura have been found too faint to produce, in any moderate time, an effect upon the nitrate of silver. To copy these images was the first object of Mr. Wedgwood in his researches on the subject, and for this purpose he first used the nitrate of silver, which was mentioned to him by a friend, as a substance very sensible to the influence of light; but all his numerous experiments as to their primary end proved unsuccessful.

Development in France

In 1829 French artist and chemist Louis Daguerre, when obtaining a camera obscura for his work on theatrical scene painting from the optician Chevalier, was put into contact with Nicéphore Niépce, who had already managed to make a record of an image from a camera obscura using the process he invented: heliography.

Daguerre met with Niépce and entered into correspondence with him. Niépce had invented an early internal combustion engine, (the Pyréolophore), together with his brother Claude and made improvements to the velocipede, as well as experimenting with lithography and related processes. Their correspondence reveals that Niépce was at first reluctant to divulge any details of his work with photographic images. To guard against letting any secrets out before the invention had been improved, they used a numerical code for security. 15, for example, signified the tanning action of the sun on human skin (action solaire sur les corps); 34 – a camera obscura (chambre noire); 73 – sulphuric acid.

The written contract drawn up between Nicéphore Niépce and Daguerre includes an undertaking by Niépce to release details of the process he had invented – the asphalt process or heliography. Daguerre was sworn to secrecy under penalty of damages and undertook to design a camera and improve the process. The improved process was eventually named the physautotype.

Niépce's early experiments had derived from his interest in lithography and consisted of capturing the image in a camera (then called a camera obscura), resulting in an engraving that could be printed through various lithographic processes. The asphalt process or heliography required exposures that were so long that Arago said it was not fit for use. Nevertheless, without Niépce's experiments, it is unlikely that Daguerre would have been able to build on them to adapt and improve what turned out to be the daguerreotype process.

After Niépce's death in 1833, his son, Isidore, inherited rights in the contract and a new version was drawn up between Daguerre and Isidore. Isidore signed the document admitting that the old process had been improved to the limits that were possible and that a new process that would bear Daguerre's name alone was 60 to 80 times as rapid as the old asphalt (bitumen) one his father had invented. This was the daguerreotype process that used iodized silvered plates and was developed with mercury fumes.

To exploit the invention, 400 shares would be on offer for 1,000 francs each; secrecy would be lifted after 100 shares had been sold, or the rights of the process could be bought for 20,000 francs.

Daguerre wrote to Isidore Niepce on 2 January 1839 about his discussion with Arago:

He sees difficulty with this proceeding by subscription; it is almost certain – just as I myself have been convinced ever since looking on my first specimens – that subscription would not serve. Everyone says it is superb: but it will cost us the thousand francs before we learn it [the process] and be able to judge if it could remain secret. M. de Mandelot himself knows several persons who could subscribe but will not do so because they think it [the secret] would be revealed by itself, and now I have proof that many think in this way. I entirely agree with the idea of M. Arago, that is get the government to purchase this discovery, and that he himself would pursue this in the chambre. I have already seen several deputies who are of the same opinion and would give support; this way it seems to me to have the most chance of success; thus, my dear friend, I think it is the best option, and everything makes me think we will not regret it. For a start M. Arago will speak next Monday at the Académie des Sciences ...

Isidore did not contribute anything to the invention of the Daguerreotype and he was not let in on the details of the invention. Nevertheless, he benefited from the state pension awarded to him together with Daguerre.

Miles Berry, a patent agent acting on Daguerre's and Isidore Niépce's behalf in England, wrote a six-page memorial to the Board of the Treasury in an attempt to repeat the French arrangement in Great Britain, "for the purpose of throwing it open in England for the benefit of the public."

Inform party that Parliament has placed no funds

at the disposal of the Treasury

from which a purchase of this description could be made

(indecipherable signature)

The Treasury wrote to Miles Berry on 3 April to inform him of their decision:

(To) Miles Berry Esq 66 Chancery Lane

Sir,

Having laid before the Lords &c your application on behalf of Messrs Daguerre & Niepce, that Government would purchase their Patent Right to the Invention known as the "Daguerreotype" I have it in command to acquaint you that Parliament has placed no Funds at the disposal of their Lordships from which a purchase of this description could be made

3rd April 1840 (signed) A. Gordon

(entry in margin) Application Refused

Without bills being passed by Parliament, as had been arranged in France, Arago having presented a bill in the House of Deputies and Gay-Lussac in the Chamber of Peers, there was no possibility of repeating the French arrangement in England which is why the daguerreotype was given free to the world by the French government with the exception of England and Wales for which Richard Beard controlled the patent rights.

Daguerre patented his process in England, and Richard Beard patented his improvements to the process in Scotland. During this time the astronomer and member of the House of Deputies François Arago had sought a solution whereby the invention would be given free to the world by the passing of Acts in the French Parliament. Richard Beard, controlled most of the licences in England and Wales with the exception of Antoine Claudet who had purchased a licence directly from Daguerre.

In the US, Alexander S. Wolcott invented the mirror daguerreotype camera, according to John Johnson's account, in one single day after reading the description of the daguerreotype process published in English translation.

Johnson's father travelled to England with some specimen portraits to patent the camera and met with Richard Beard who bought the patent for the camera, and a year later bought the patent for the daguerreotype outright. Johnson assisted Beard in setting up a portrait studio on the roof of the Regent Street Polytechnic and managed Beard's daguerreotype studio in Derby and then Manchester for some time before returning to the US.

Wolcott's Mirror Camera, which gave postage stamp sized miniatures, was in use for about two years before it was replaced by Petzval's Portrait lens, which gave larger and sharper images.

Antoine Claudet had purchased a licence from Daguerre directly to produce daguerreotypes. His uncle, the banker Vital Roux, arranged that he should head the glass factory at Choisy-le-Roi together with Georges Bontemps and moved to England to represent the factory with a showroom in High Holborn. At one stage, Beard sued Claudet with the aim of claiming that he had a monopoly of daguerreotypy in England, but lost. Niépce's aim originally had been to find a method to reproduce prints and drawings for lithography. He had started out experimenting with light-sensitive materials and had made a contact print from a drawing and then went on to successfully make the first photomechanical record of an image in a camera obscura – the world's first photograph. Niépce's method was to coat a pewter plate with bitumen of Judea (asphalt) and the action of the light differentially hardened the bitumen. The plate was washed with a mixture of oil of lavender and turpentine leaving a relief image. Later, Daguerre's and Niépce's improvement to the heliograph process, the physautotype, reduced the exposure to eight hours.

Early experiments required hours of exposure in the camera to produce visible results. Modern photo-historians consider the stories of Daguerre discovering mercury development by accident because of a bowl of mercury left in a cupboard, or, alternatively, a broken thermometer, to be spurious.

Another story of a fortunate accident, which modern photo historians are now doubtful about, and was related by Louis Figuier, of a silver spoon lying on an iodized silver plate which left its design on the plate by light perfectly. Noticing this, Daguerre supposedly wrote to Niépce on 21 May 1831 suggesting the use of iodized silver plates as a means of obtaining light images in the camera.

Daguerre did not give a clear account of his method of discovery and allowed these legends to become current after the secrecy had been lifted.

Letters from Niépce to Daguerre dated 24 June and 8 November 1831, show that Niépce was unsuccessful in obtaining satisfactory results following Daguerre's suggestion, although he had produced a negative on an iodized silver plate in the camera. Niépce's letters to Daguerre dated 29 January and 3 March 1832 show that the use of iodized silver plates was due to Daguerre and not Niépce.

Jean-Baptiste Dumas, who was president of the National Society for the Encouragement of Science (Société d'encouragement pour l'industrie nationale) and a chemist, put his laboratory at Daguerre's disposal. According to Austrian chemist Josef Maria Eder, Daguerre was not versed in chemistry and it was Dumas who suggested Daguerre use sodium hyposulfite, discovered by Herschel in 1819, as a fixer to dissolve the unexposed silver salts.

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