Daguerreotypes

The first permanent images were obtained by the French landowner . N. Niepce using bitumcn-coated pewter (bitumen hardens when expo.sed to light for several hours and the unexposed portions can then be dissolved away in oil of turpentine). He then helped the portrait painter, L. J. M. Daguerre, to perfect the daguerreotype process which utilized plates of copper coated with silver sensitized with iodine vapour. The announcement of this process in 1839 was greeted with enormous enthusiasm but it. suffered from the critical drawback that each picture was unique and could not be duplicated. 

Portrait of Berzelius from a daguerreotype taken in Berlin in 1845, three years before his death0... 

The daguerreotype process may be considered the most perfect of all the photographic processes at present known for certainly it stands unequalled for microscopic perfection of detail, modulation of shade, and beauty of half-tone nor is this superiority to bo wondered at whan it is considered that the chemicals ore applied in the form of impalpable vapor, and that the tablet is a highly polished metal plate while in other processes the chemicals are either contained in a coarse material like paper, or else in a gummy film, which is spread Upon glass, leather, or enamel. -... 

Daguerreotypes are permanent when the manipulation Is properly performed, the plate thoroughly washed, and carefully sealed up in an air-tight case. In order to avoid the reversion of the image, a reflector must be us d in front of the lens, an expedient which is not necessary in any other process. 

BECQUEREL EFFECT, A photographic effect discovered by E, Becquerel (1895). Experimenting with the daguerreotype process. Becquerel found that a plate will produce a direct (positive) image if exposed first to diffuse daylight. See also Photochemistry and Photolysis and Photography and Imagery. 

Newhall, B. Daguerreotype in America, 3rd Edition, Dover Publications, Inc, Mineola, NY. 1999,... 

A suggested example of a daguerreotype is Girl with a Portrait of Washington, Southworth and Hawes, mid-nineteenth century. Also, any examples of daguerreotype from books listed in the References section at the end of this chapter may be used. 

This was the very first toning approach for photographic prints and was taken directly from the technique used to gild daguerreotypes except that in that technique heat was applied to the underside of the plate during the process. 

French Academy of Sciences that he called the daguerreotype, which we now know as photography. 

Although polyester film, introduced by Du Pont under the trade name Mylar in the 1960s, has been added to the traditional supports like paper and cellulose acetate, the principle of photographic film preparation has remained unchanged since daguerreotype was developed. The sensitive surface always contains a silver halide crystal emulsion with a gelatin binder. Despite all the efforts to replace them, silver salts remain the basis of these emulsions, and film manufacturers still require gelatin, which they consume at the rate of 20,000 tons a year. The suppliers are few, and they are carefully selected. The world leader in this area is Rousselot, now a subsidiary of Sanofi Elf Aquitaine, with four units in Europe and one in the United States. 

Shellac is dark in colour, and is usually dyed black, red or brown. Its best known uses were as gramophone records. Another use was for American Union cases, which were small boxes used as folding picture frames (Fig. 13.1). They could be closed to preserve the silver nitrate coated glass photo des called Daguerreotypes, which deteriorate in the h t. Shellac was also used fin dressing table sets and for brooches. It is a britde material and can crack or chip. Shellac is compression moulded, and is still produced today. 

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