Photochrom
Encyclopedia
Photochrom"Photochrom" is the spelling used by the Library of Congress
, for historical reasons, in its classification and description of its collection of such images. Variants of the spelling exist, both in English and in German. "Photochrome" is the English spelling used in some contexts, e.g. even by the Library of Congress in its descriptions of a few of its images. "" is the German spelling used today by Orell Füssli, the Swiss company that originally invented the process. (also called the Aäc process) prints are colorized
images produced from black-and-white photographic negatives via the direct photographic transfer of a negative onto lithographic
printing plates. The process is properly considered a photographic variant of chromolithography
, a broader term referring to color lithography in general.
, a printing firm with a history extending back into the 16th century. Füssli founded the stock company Photochrom Zürich (later Photoglob Zürich AG) as the business vehicle for the commercial exploitation of the process and both Füssli and Photoglob continue to exist today. From the mid 1890s on the process was licensed by other companies including the Detroit Photographic Company in the US and the Photochrom Company of London.
The photochrom process was most popular in the 1890s, when true color photography
was first being developed but was still commercially impractical.
In 1898 the US Congress passed the Private Mailing Card Act which allowed private publishers to produce postcards. These could be mailed for one cent each — the letter rate at the time was two cents. Thousands of photochrom prints, usually of cities or landscapes, were created and sold as postcards and it is in this format that photochrom reproductions became most popular. The Detroit Photographic Company reportedly produced as many as seven million photochrom prints in some years, and ten to thirty thousand different views were offered.
After World War One, which brought an end to the craze for collecting Photochrom postcards, the chief use of the process was printing posters and art reproductions, and the last Photochrom printer operated up to 1970.
, known as a "litho stone," is coated with a light-sensitive coating, comprising a thin layer of purified bitumen dissolved in benzene
. A reversed half-tone negative
is then pressed against the coating and exposed to daylight for a period of 10 to 30 minutes in summer, up to several hours in winter. The image on the negative allows varying amounts of light to fall on different areas of the coating, causing the bitumen to harden and become resistant to normal solvents in proportion to the amount of light that falls on it. The coating is then washed in turpentine
solutions to remove the unhardened bitumen and retouched in the tonal scale of the chosen color to strengthen or soften the tones as required. Each tint is applied using a separate stone bearing the appropriate retouched image. The finished print is produced using at least six, but more commonly from 10 to 15, tint stones.
Library of Congress
The Library of Congress is the research library of the United States Congress, de facto national library of the United States, and the oldest federal cultural institution in the United States. Located in three buildings in Washington, D.C., it is the largest library in the world by shelf space and...
, for historical reasons, in its classification and description of its collection of such images. Variants of the spelling exist, both in English and in German. "Photochrome" is the English spelling used in some contexts, e.g. even by the Library of Congress in its descriptions of a few of its images. "" is the German spelling used today by Orell Füssli, the Swiss company that originally invented the process. (also called the Aäc process) prints are colorized
Hand-colouring
Hand-colouring refers to any method of manually adding colour to a black-and-white photograph, generally either to heighten the realism of the photograph or for artistic purposes...
images produced from black-and-white photographic negatives via the direct photographic transfer of a negative onto lithographic
Lithography
Lithography is a method for printing using a stone or a metal plate with a completely smooth surface...
printing plates. The process is properly considered a photographic variant of chromolithography
Chromolithography
Chromolithography is a method for making multi-color prints. This type of color printing stemmed from the process of lithography, and it includes all types of lithography that are printed in color. When chromolithography is used to reproduce photographs, the term photochrom is frequently used...
, a broader term referring to color lithography in general.
History
The process was invented in the 1880s by Hans Jakob Schmid (1856–1924), an employee of the Swiss company Orell Gessner FüssliOrell Gessner Füssli
Orell Gessner Füssli was a bookshop in Zürich, Switzerland at the end of the 18th century, established by the successors of Christoph Froschauer...
, a printing firm with a history extending back into the 16th century. Füssli founded the stock company Photochrom Zürich (later Photoglob Zürich AG) as the business vehicle for the commercial exploitation of the process and both Füssli and Photoglob continue to exist today. From the mid 1890s on the process was licensed by other companies including the Detroit Photographic Company in the US and the Photochrom Company of London.
The photochrom process was most popular in the 1890s, when true color photography
Color photography
Color photography is photography that uses media capable of representing colors, which are traditionally produced chemically during the photographic processing phase...
was first being developed but was still commercially impractical.
In 1898 the US Congress passed the Private Mailing Card Act which allowed private publishers to produce postcards. These could be mailed for one cent each — the letter rate at the time was two cents. Thousands of photochrom prints, usually of cities or landscapes, were created and sold as postcards and it is in this format that photochrom reproductions became most popular. The Detroit Photographic Company reportedly produced as many as seven million photochrom prints in some years, and ten to thirty thousand different views were offered.
After World War One, which brought an end to the craze for collecting Photochrom postcards, the chief use of the process was printing posters and art reproductions, and the last Photochrom printer operated up to 1970.
Process
A tablet of lithographic limestoneLithographic Limestone
Lithographic limestone is hard limestone that is sufficiently fine-grained, homogeneous and defect free to be used for lithography. Geologists use the term lithographic texture to refer to a grain size under 1/250 mm...
, known as a "litho stone," is coated with a light-sensitive coating, comprising a thin layer of purified bitumen dissolved in benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....
. A reversed half-tone negative
Negative (photography)
In photography, a negative may refer to three different things, although they are all related.-A negative:Film for 35 mm cameras comes in long narrow strips of chemical-coated plastic or cellulose acetate. As each image is captured by the camera onto the film strip, the film strip advances so that...
is then pressed against the coating and exposed to daylight for a period of 10 to 30 minutes in summer, up to several hours in winter. The image on the negative allows varying amounts of light to fall on different areas of the coating, causing the bitumen to harden and become resistant to normal solvents in proportion to the amount of light that falls on it. The coating is then washed in turpentine
Turpentine
Turpentine is a fluid obtained by the distillation of resin obtained from trees, mainly pine trees. It is composed of terpenes, mainly the monoterpenes alpha-pinene and beta-pinene...
solutions to remove the unhardened bitumen and retouched in the tonal scale of the chosen color to strengthen or soften the tones as required. Each tint is applied using a separate stone bearing the appropriate retouched image. The finished print is produced using at least six, but more commonly from 10 to 15, tint stones.
External links
- About Photochroms
- The Photochrom Process
- The Library of Congress Public Domain Photochrom Prints Search
- Digitalised Photochrom prints of the Zurich Central LibraryZentralbibliothek ZürichZentralbibliothek Zürich is the main library of both the city and the University of Zürich, housed in the Predigerkloster, the former Black Friars' abbey, in the old town's Rathaus quarter....
(holds worlds largest collection: of their prints are accessible online)