Daguerreotype Process

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The Daguerreotype was the World's first practical photographic system. The process was invented by French artist & scientist Louis Jacques Mandé Daguerre over a long period between 1821-1837, inspired by a period of cooperation with the inventor of photography, Nicéphore Niépce. Daguerre gave the rights to use his new process, in exchange for pensions for himself and for Niépce's son, to the French government in 1839. The government gave the rights "free to the World" because in the year of the 50th Anniversary of the French Revolution "the French state was keen to demonstrate the nations's enterprising spirit"[Font-Réaulx].

The Cameras

Daguerre's construction Le Daguerreotype gave the model for the most early cameras, for the sliding box camera type which was derived from similar camera obscura models.

The Images

The Daguerreotype is a mirrored negative image that appears as positive image when no reflections of bright light disturb the view on it. It was made on a prepared polished metal plate, thus allowing no making of prints from the negative. The process was capable of very fine detail and subtle tones. Each image had to be protected by airtight enclosure in a frame with glass plate. The system became cheaper after a while when the process was improved and small format plates became standard for portraiture, cheap enough to allow many people access to photographs of family members (especially of themselves ;-). In a very short time, Daguerreotype studios proliferated across the World: Paris had 12 in 1844, New York City is said to have had over 70 by 1850.

The Process

There are five stages in making a Daguerreotype, plus optional toning, and finally mounting:

  1. Plate Preparation: a polished copper sheet is plated with silver (by Sheffield plating, or, later, by electroplating); this is then polished to a very high gloss.
  2. Sensitisation: the plate is placed in an iodizing box and exposed to iodine vapour until all the surface silver has been converted to silver iodide, turning the plate orange. This is the light-sensitive coating. This had to be done shortly before the exposure, as iodized plates would rapidly degrade.
  3. Exposure: The plate is loaded into a camera, and an exposure made simply by removing the lens cap. Exposures in early cameras could be over twenty minutes, even in bright daylight! However, this was less than some other, earlier processes. In 1840, Englishman John Goddard showed that sensitivity could be increased by using bromine, as well as iodine; this, together with improving lens technology brought times down considerably. Petzval's lens in particular brought typical apertures down from ~f14 to ~f3.5 - four stops improvement, i.e. potentially 16 times shorter exposures.
  4. Development: the plates, kept in the dark, are suspended over a bath of mercury, which is heated to 60°C (140°F); mercury vapour forms an amalgam with the exposed silver iodide.
  5. Fixing: unexposed silver iodide, not amalgamated with mercury, is washed off the plate using a salt (sodium chloride) solution (later replaced by weak sodium thiosulphate solution). This leaves the mercury/silver amalgam highlights and shadows of the original silver as a permanent - but delicate - image.
  6. Toning: Original Daguerreotype images were extremely delicate, and could be marred by even a slight touch. In 1840, French physicist Hippolyte Fizeau (1819 – 1896) discovered that a heated gold chloride solution could both reduce the fragility and improve the tone of the image.
  7. Mounting: The plate was usually sealed into a glass-fronted frame to protect the fragile surface from being scratched, or oxidising (tarnishing to black, as silver cutlery does) in the air.


Disadvantages

The Daguerreotype had several problems:

  • There was no negative; each individual exposure made only one Daguerreotype - copies or enlargements were not possible except by photographing a new, inferior, Daguerreotype of the original. Some Daguerreotypes were engraved to make printing plates. Daguerre himself hindered professor Alfred Donné's introduction of a more sophisticated etching method for making printing plates from Daguerreotypes.
  • Long - or very long - exposure times - made sharp images of people almost unattainable with early lenses & plates.
  • The photograph had to be viewed in good light, and carefully angled to be seen well; viewing at the wrong angle made the image appear as a negative.
  • The plates were not transparent and so the image is viewed from the same side as the lens - hence the picture is normally left-right reversed. Some cameras incorporated a mirror to correct this during exposure - but most Daguerreotypes are "mirror images".
  • The silver plates and processing (and the individual exposure/processing cycle for each picture) were expensive.
  • The images were very fragile.
  • The process involved highly poisonous bromine & mercury vapours.

However, in spite of these drawbacks, Daguerreotypes were popular and the process spread across the world. One exception was in the British Empire; whilst the French government had given rights to the World, the Daguerreotype had been patented in Britain and hence its colonies - which encouraged use of many other processes. Talbot's Calotype negative process for pictures on paper rivalled the Daguerreotype process, but Daguerreotypes were generally preferred for portraiture, the main subject of the 1840s' photography. After Daguerre and Talbot, Hippolyte Bayard was the third renowned photographer to introduce an own photographic process in 1839, one for pictures on paper. Bayard's process was the only one acknowledged by the French Académie des Beaux-Arts as a means to create art.

Daguerreotype photography continued until the late 1850s - particularly in France - until largely replaced by the Ambrotype process or other positive variants of Archer's wet-collodion process, originally a negative process that also replaced the Calotypes.

Daguerreotype Cameras

Sources

  • The Focal Encyclopedia of Photography, Focal Press/Elsevier, 4th ed., 2007
  • Coe, Brian, Cameras, from Daguerreotypes to Instant Pictures, Norbok, 1978
  • Coe, Brian, The Birth of Photography, Ash & Grant, 1976
  • Neher, Frank Ludwig Die Erfindung der Photographie, Stuttgart 1938
  • Smith, R. C., Antique Cameras, London and Vancouver 1975
  • de Font-Réaulx, Dominique, Photography at the Musée d'Orsay: The Daguerreotype, Paris 2008

Links