Untitled No. 1121
Serial No. 1121
© Mark Kessell 2007
IntroductionThe daguerreotype is a very early - many would say the first - photographic process. The process is named after the man credited with making the technique public in Paris, in August 1839 – Louis-Jacques-Mandé Daguerre. It uses a sensitized silver plate – a “mirror with a memory” - to “fix an image taken directly from nature”.
In the nineteenth century, this new medium was used almost exclusively with commercial rather than artistic intentions. It was a means of making “realistic” but usually highly stylized portraits and keepsakes for those who might otherwise have commissioned a painter. Although the codified rituals and stilted poses adopted by the makers and subjects of early daguerreotypes look dated and artificial to most modern viewers, daguerreotypes, old or new, have a captivating immediacy which has attracted increasing numbers of contemporary collectors.
The process, practiced today by only a few people worldwide, is complex, laborious and utilizes toxic elements such as bromine, iodine and mercury. It produces a unique photographic image on a silver plate. Because no two plates have identical chemical properties, no two completed daguerreotypes ever look identical.
Daguerreotypes are both more fragile and more durable than most photographic media. When kept away from air and human fingers, they are widely considered the most archival and long lasting of all photographic forms.
Daguerreotypes are best displayed using a narrow-beam halogen spotlight directed downwards from above. Ideally, the surface opposite the daguerreotype – for example, the wall on the opposite side of a room – should be a dark color like black, gray or navy-blue. This is not essential, but it will enhance the visibility of the image. Conversely, displaying a daguerreotype opposite a white wall or a sunlit window will reduce the visibility of the image.
SafetyMany of the chemicals used in producing a daguerreotype are highly toxic, and can be rapidly fatal if absorbed into the body. A high-extraction fume hood of the type used in chemical laboratories is part of the standard equipment of most contemporary daguerreotypists. In the nineteenth century, when mercury was widely considered curative for certain ailments, few precautions were taken to ensure safety. It was not uncommon for daguerreotypists and their helpers to suffer neurological and other (sometimes lethal) symptoms after inhalation of the fumes. Now, of course, we know that mercury and bromine are extremely dangerous, so contemporary daguerreotypists take immense care to insulate themselves from exposure.
What follows is not a practical manual but a description of the technique for the curious. If you want to make a daguerreotype yourself it is essential to learn safe procedures for all aspects of the process, which is best done by being personally taught the technique by an experienced practitioner.
MaterialsA daguerreotype relies upon an even and highly reflective surface of pure silver, the active element in producing a light-sensitive surface. Most contemporary daguerreotypists use a silver-coated copper plate for their work, as was usual in the 19th century). Other substrates, like brass, respond to silvering equally well.
There are as many variations in both materials and technique as there are daguerreotypists, but the basic technical principles of the process are as follows:
Machine PolishingThe first step in making a daguerreotype, polishing the plate, is laborious but crucially important. At the time of its manufacture, the plater usually machine polishes the plate, although this rarely achieves the perfect surface that most daguerreotypists seek. Most daguerreotypists today begin preparing a plate by machine polishing it again sequentially applying up to 3 separate “cutting” agents.
The first, rottenstone, is a form of finely crushed limestone which is mixed with a drop of olive oil to act as lubricant. A polishing wheel or random orbital sanding pad is rotated across the plate’s surface with gentle pressure, allowing the rottenstone to “cut” away surface oxidization and other imperfections. Next, jewelers’ rouge, (desiccated and finely powdered iron oxide - known to most of us as rust), is applied. Lastly, the finest of all the cutting agents, lampblack, a pure form of particulate carbon imparts a lustrous sheen to the silver surface.
Hand PolishingThe next phase in preparation – hand polishing - is said by many experienced daguerreotypists to be the single most important step in producing a technically flawless image. The plate is buffed with a velvet or buckskin leather paddle in two or even three separate stages. The buffs are primed with a little of the cutting compounds and the plate is vigorously but carefully rubbed to produce the exquisite mirror-like sheen characteristic of the daguerreotype. The final buffing stage is performed with no polishing compound at all, the bare buff serving to remove the last traces of particulate residue and any haze from the rouge or lampblack. At this point, the plate is ready to be made light sensitive.
SensitizationWith the hard work of polishing complete, the creation of the daguerreotype enters one of its most beautiful stages - the creation of a light-responsive layer of silver iodide. This is achieved by exposing the plate to iodine vapor inside a sealed box turning its surface from a colorless mirror to an even wash of yellow, rose, lilac, silvery-blue or even, in extreme cases, bright green. The early portions of this color sequence seem to produce the most light responsive daguerreotypes so the process is usually halted when the plate is a deep yellow tinted with rose.
In Monsieur Daguerre’s day the plate was considered ready for exposure at this point. At the beginning of the “daguerreian era” the time required for production of a well-defined image with a wide-open lens would be around 8 – 20 minutes under bright sunlight. The original practitioners of the process did not have a method of shortening this exposure time until the late 1840’s when bromine became commercially available and was used to make “Quick”, or “bromide of lime” – essentially a small amount of elemental bromine mixed with finely crushed chalk. The bromine vapor produced by this “Quick” reduces the exposure time to between 5-60 seconds on a bright day and permits a crisp, high contrast image of a living subject.
After exposure to bromine, the plate is exposed to iodine one last time before being enclosed in a light-proof holder which is inserted into the camera to make the image.
DevelopmentOnce a latent image has been captured by exposure of the plate to light, the image must be developed. Using a high-extraction fume hood to ensure safety, the plate is inserted into a box containing heated mercury vapor. After around 3 minutes in mercury vapor, the image is clearly visible, but will disappear in the presence of white light if nothing is done to preserve it. Now it is necessary to “fix” the image (i.e. make it permanent in the presence of daylight).
FixingThis phase caused much delay in perfecting the process during the 1830’s. Daguerre and his partner Joseph Nicéphore Niépce tried many substances which they hoped would fix the image. Eventually when they tested a solution of sodium thiosulfate, readily and cheaply available even in their time, they achieved their goal. Today, most daguerreotypists still fix plates using the same simple formula proposed by Daguerre and Niépce.
If everything has progressed according to plan, the daguerreotype image is complete and permanent but for one final step.
GildingAfter fixing, the daguerreotype image is incredibly fragile. The slightest brush of a fingernail or even a hair will remove the silver-mercury amalgam which comprises the image. To increase the durability, a heated solution of gold-chloride is used to tone the plate and harden the surface, imparting, in the process, a warm, slightly yellowish glow to the image. This technique, known as “gilding”, is not essential although it does make the image a little less fragile. Image permanence is virtually assured if the plate is maintained in an airtight environment – usually by sealing it behind a piece of glass. If the surface is not exposed to air or physical trauma, the image will last almost indefinitely. The daguerreotype is still the most archival of all photographic processes, outlasting color photography by over 150 years and traditional black and white photography by more than 50 years.