Glossary
Additive color process color plate
A colored transparent image on glass, commonly referred to as an autochrome. Since the 1890s, additive color processes have
been used to create color photographs. The process relies on screen plates recording red, green, and blue (the primary colors of light)
to produce a color image. The three plates are carefully superimposed to register as one unit in making a seamless full-color
image. Some additive color processes juxtapose layers of color with transparent reflectors, separation negatives, or transparencies.
While several early patented processes produced color plates, the
Lumière autochrome was the first color transparency to gain
popularity and was widely used into the 1940s. Images were produced as glass plate color transparencies. Starch grains dyed
red-orange, blue-violet, and green were spread in equal amounts on a varnished glass surface, which was varnished again and coated with
an emulsion sensitive to all colors of light. After exposure in the camera, where light passed through the starch filters before
reacting with the light-sensitive emulsion, the coated plates were developed, washed, and then bleached out to a negative image. Exposure
to white light and a second development process produced a positive image, which was fixed, washed, and then varnished. Patented
by the Louis Lumière (1862-1954) in 1904, these autochromes were noted for their soft, pointillist quality and ranged in size from
less than two inches square (5.1 cm) to 15 x 18 inches (38.1 x 45.7 cm).
Agfacolor
See chromogenic process color print.
Albumen print
The primary photographic print up until about 1890. Invented by Louis-Désiré Blanquart-Évrard (1802-1872) in 1850, the method
fell out of favor only when gelatin coated papers were introduced. Because albumen prints allowed greater detail while
maintaining reproducibility, they were an improvement on the
salted paper print. To make a print, a sheet of thin, high-quality writing paper
was coated in a bath of albumen emulsion (a liquid binder of egg white containing salt). The emulsion filled the pores of the paper
to create a smooth surface, ranging from a slight sheen to a thick, glossy finish depending upon the desired effect. When dry, the
paper was made light sensitive with a silver nitrate solution and placed in dark storage. In a darkroom, the prepared paper was put in
a hinged, wooden frame in contact with the usual glass or occasional waxed paper negative and exposed to sunlight to print the
image. The exposure could take from as little as a few minutes to an hour or more. This is a "printing-out" techniqueno chemical
development process was necessary to make the image visible. After exposure, the print was immersed in a fixing bath to prevent
further chemical reactions, washed, and finally dried.
The lustrous surface of the albumen print was often used with a
wet collodion negative, which demanded a printing paper that
could provide more detail and contrast than plain salted papers. Albumen prints, which were a reddish-brown, were later toned with
gold chloride, which produced a purplish-brown color and made them more permanent. The thin paper was ideal for mounting on
larger sheets bound into albums. The surface is delicate, can become cracked, and the highlights yellow in photographs where the
coating has deteriorated.
Albumenized salted paper print
A photograph printed from a negative on to a piece of salted paper coated with a layer of albumen (a solution of egg white and
salt). The albumenized surface of a salted paper print renders a clearer image than one not albumenized but has less detail than an
albumen print and warmer tones and yellowish highlights. Albumenized salted paper prints could be made from
wet collodion on glass, dry
collodion on glass, or paper or waxed paper
negatives.
Albums
A popular means of storing loose photographs in book form. Since the 1850s, albums have been a convenient way to display prints
of friends and family and travel vistas. Published "picture book" albums and single sheets of pictures could be purchased.
Photographs were adhered to the pages or inserted into slits or pockets.
Aperture
A device controlling the amount of light that enters a camera through its lens. The aperture, a measured opening, usually has the
form of overlapping thin metal leaves arranged in a circle. A mechanical device, it can be made to open and close.
Applied color
Color applied by hand in the form of paint or dyes to black-and-white photographs to alter details and achieve various effects.
Artists can add color using brushes, cotton swabs, or airbrushes. A photographer can brighten and lighten highlights of the print and
increase tonal range by applying color. As early as 1842, hand coloring started with
Daguerreotypes.
Artist's proof
A specified number of prints from the first run of a negative that are reserved for the artist's personal use.
Assembly process color print
Commonly known as carbro prints (from
carbon and bromide) and most frequently used to create bright, vivid color images
for advertising from 1919 until the early 1940s. The carbro process is based on the addition of dyes to the carbon printing process,
a highly complicated procedure involving as many as eighty steps. A further evolution of this process, the
three-color carbro print was introduced by D. A. Spencer in 1935. In this process three individual negatives are made by shooting one each through a red, a
green, or a blue filter. From these negatives three bromide prints are made, each still retaining the color from its original filter, which are
then transferred onto separate, thin gelatin tissues. The tissues (color separations) are stacked in careful alignment on a base paper
to produce one full-color, permanent image.
Attribution
The assignment of a work of art to a particular artist, based upon the close study of traits, characteristics, and stylistic evidence.
An attribution can be made by comparing a work to others that have been unequivocally assigned to the artist, based on solid
evidence such as a signature.
Blanquart-Évrard process
Enhancements to salted paper prints introduced by Louis-Désiré Blanquart-Évrard in 1851. This process produced a paper
very sensitive to light and less susceptible to fading, so that it needed just a few seconds exposure time before being developed.
After being soaked in a solution of gelatin potassium bromide and iodide, the paper was dried and stored. Before exposure it was
sensitized to light with a solution of silver nitrate and nitric acid. The improvements in the developing speed allowed several
hundred prints to be printed quickly from one negative, mostly for mounting in books or albums. Blanquart-Évrard's technical
changes stimulated the short-lived, but distinguished period of French salt prints by such artists as Édouard Baldus, the Bisson
brothers, Nadar, Charles Négre, and Henri-Victor Regnault.
Blindstamp
An inkless impression embossed directly on a photograph or the mount to which it is attached, used for identification
purposes. Popular during the nineteenth century and in some commercial photography today, blindstamps usually spell the name and
address of the photographer or, in some instances, the collector.
Bromoil print
A contact print or, more often, an enlargement made on gelatin silver bromide paper treated with a solution of potassium
bichromate to bleach out the dark silver image. This process hardened the gelatin, preparing it to absorb the hand coloring of
oil-based pigments applied with special brushes. The word
bromoil is a combination of the original
bromide print and the oil pigments. Bromoils can be produced in any color, with a broad tonal range and a wide latitude for changing the appearance of the image,
but they do not have the clarity and resolution of
gelatin silver prints. Developed around 1907 by C. Welbourne Piper and Edward
John Wall (1860-1928), the bromoil process was popular with pictorialist photographers and the Photo-Secessionists until the
1930s.
Burning-in and dodging
Techniques used in printing to alter the tonality of an image by darkening areas that are too light and lightening areas that are
too dark. For part of the exposure time the photographer interposes something opaque, such as a piece of cardboard or paper,
between the image and the light source, moving it back and forth to control the exposure throughout specific areas of the print surface.
A hole pierced in the cardboard or paper can also direct light strategically onto the photographic surface.
|
