| Everything You Ever Wanted to Know About Your Family Photographs | |
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Other Lesser
Known Processes
The next 40 years in photographic history became experimental with many new processes and techniques being used. Because there were far less of these photographs produced, it is not as necessary to elaborate on these processes as with the more major contributions.
Crayon
Portraits
Crayon portraits were made from the 1860's through the turn of the 20th century.
A weak photographic image was used as the basis for the extensive handwork with
charcoal or pastels. They were usually life sized and were neutral black images
on a matte-surfaced paper as the underlying photographic 'sketch.'
Carbon
Prints
In 1839 Mungo Ponton discovered a new process based on the light sensitivity of
bichromates. When added to gelatin, bichromates render the coating insoluble
upon exposure to light. In other words, wherever light touched the coating, that
part of the emulsion would not dissolve away. Carbon black was one of the first
pigments used, hence the name - carbon prints. Sometimes pigments were chosen
for their ability to mimic albumen print image colors. The beauty and durability
of carbon prints was undisputed, but they were too time-consuming and difficult
to challenge the silver papers.
Platinum
Prints (Platinotypes)
A platinum print, or platinotype, consists of finely divided platinum metal and
are exceptionally stable. The process came into use around 1880 and was popular
until about 1930. These prints have a matte surface; most have a steely-gray
image color, although some variations of the process produced browner image
hues.
Cyanotypes
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| This is the actual and true color of a cyanotype. |
The cyanotype, or 'blueprint' process, was another of astronomer Sir John Hershel's contributions to photography. Although the process dates back to the 1840's, it was used rather infrequently until the 1880's. Like the platinotype, the cyanotype has a matte surface and its process is based on the light sensitivity of iron salts. The image stability of cyanotypes is good, though not as stable as the platinotype. Cyanotypes fade when exposed to light, but the lost image density is regained in large measure during storage in the dark. Gelatin and collodion printing-out papers became popular in the mid 1800's, replacing albumen paper as the dominant photographic printing material. These papers were the forerunners of our modern photographic papers. They no longer had to be coated by the photographer and were coated on long continuous rolls with much greater sensitivity to light. These papers offered a wide range of surfaces, image colors and contrasts and their image stability was superior. Sales of slow developing-out papers increased dramatically in the last three or four years of the 19th century, led by an ever-increasing number of amateurs.
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