NotesThe daguerreotype was a remarkably complex process. To make a daguerreotype you firstly had to clean a piece of silver plate to a mirror finish using a slurry made from pumice in oil, then give it a number of washings in nitric acid and water to remove the oil residue. Secondly the prepared plate had to be sensitised by exposing it to iodine vapour. Then the sensitised plate was placed in a camera and exposed to light, the exposure time varied according to the time of the day, the season of the year and the weather, and could be from three to thirty minutes. The silver plate was then exposed over heated mercury vapour until an image appeared and lastly it was fixed by placing the plate in a hot solution of common salt or a solution of sodium thiosulfate.
Keeping a supply of the correct chemicals, making sure the plates and workspace were kept free of dust and ensuring there was a supply of clean water all conspired to limit the practicality of travelling with a camera. This coupled with the lengthy exposure times, which were a result of deficiencies of these early photographic emulsions and the quality of the camera's lens, made the whole process complicated and unwieldy.
Geoff Barker, Curatorial, September 2009
Janet Burger, French Daguerreotypes, University of Chicago Press, Chicago, 1989
Helmut and Alison Gernsheim, A Concise History of Photography, Thames and Hudson, Germany, 1965
Rudolf, Kingslake, A History of the Photographic Lens, Academic Press Limited, San Diego, California, 1989
Naomi Rosenblum, World History of Photography, Abbeville Press, New York, 1984