Daguerreotype
Invented by Louis-Jacques-Mandé Daguerre and introduced worldwide in 1839, daguerreotype was almost completely superseded by 1860 with new, less expensive processes yielding more readily viewable images. In the late 20th century, there was a revival of daguerreotypy by a small number of photographers interested in making artistic use of early photographic processes.
Daguerreotype
Usually, it was arranged so that sitters leaned their elbows on a support such as a posing table, the height of which could be adjusted, or else head rests were used that did not show in the picture, and this led to most daguerreotype portraits having stiff, lifeless poses. Some exceptions exist, with lively expressions full of character, as photographers saw the potential of the new medium, and would have used the tableau vivant technique. These are represented in museum collections and are the most sought after by private collectors today. In the case of young children, their mothers were sometimes hidden in the frame, to calm them and keep them still so as to prevent blurring.
The image in a daguerreotype is often described as being formed by the amalgam, or alloy, of mercury and silver because mercury vapor from a pool of heated mercury is used to develop the plate; but using the Becquerel process (using a red filter and extra exposure) daguerreotypes can be produced without mercury, and chemical analysis shows that there is no mercury in the final image with the Becquerel process. This brings into question the theory that the image is formed of amalgam with mercury development.