Negative Paper

The Lille-based experimenter would go on to develop several other variants of paper negatives based on albumen, serum and whey.

The calotype however then enjoyed a notable success, especially with amateurs and artists such as Charles Le Nègre, Henri Le Secq, Charles Marville and Gustave Le Gray in France. Those using calotypes formed photography circles and societies: the Calotype Society in England, a circle around Robert Adamson in Scotland, the Roman Photographic School (Caffè Greco group), and several other groups in France within the Manufacture de Sèvres (Victor Regnault) and the Société héliographique. The process, because of the long exposure time, was not totally suited to portraits, it was more popular for outdoor and travel photography as well as still lifes.

In 1851, Gustave Le Gray perfected the Talbot procedure with his dry waxed paper process. This technique, which recommends waxing the paper before sensitizing it, extends the shelf life of prepared papers and gives greater transparency to produced negatives. However, it also lengthens the exposure time. The paper negative process was gradually abandoned in the late 1850s in favour of glass plate negatives, which produce higher-quality images. The idea of using paper as the primary medium for photography was, however, revived at the end of the 19^th century by George Eastman; in 1884, the Eastman Dry Plate and Film Company (Eastman Kodak) began producing rolls of sensitized paper, inventing the first films (a flexible medium for negative images to be scrolled through the camera). Because the resulting images were only of mediocre quality, Kodak replaced the paper with a flexible nitrate-based film base starting in 1888. This idea is also reflected in the more contemporary practice of pinhole photography, where paper serves as the photographic medium. Both Kodak paper negatives and pinhole negatives use the gelatin-silver bromide process.

Manufacturing

Calotypes are produced as follows: a high-quality sheet of paper is coated with a silver nitrate solution using a paintbrush, then dried.

It is then immersed for a few minutes in a potassium iodide solution, which triggers an initial sensitisation process through the formation of silver iodide. After being dried again, this time in the dark, it is treated with "gallo-nitrate of silver," a solution consisting of silver nitrate, gallic acid and acetic acid. Once it is rinsed, the sheet, wet or dry, must be quickly placed in the camera to capture the image. Exposure produces a latent image, barely visible to the naked eye, which is revealed by development in a solution of gallo-nitrate of silver. The developed image is then stabilized in a potassium bromide bath -although this was gradually replaced in the second half of the 1840s with sodium thiosulfate, called “hyposulfite of soda” at the time. The resulting negative is usually coated with wax for more transparency. Until the 1850s, salted paper prints were made by contact with paper negatives in a printing-frame (the calotype process refers to both the negative and the positive produced from the negative). 

Identification

It is not always easy to identify a paper negative at first glance: when viewed in transmitted light, the illuminated parts of the subject appear black, and the dark parts appear light. When viewed in reflected light, the whites of the negative appear yellow, and the blacks are dark and opaque. Paper negatives come in non-standard sizes, and their edges are often unevenly cut.

Deterioration

Paper negatives may have mechanical damage typical of the paper substrate: tears, folded corners, and missing sections. The wax used to coat the negatives may deteriorate over time, yellow, or crack, creating marks that interfere with the viewing of the photographic image.

Glossary