1078
in September 1840, by his pivotal discovery of the
much faster calotype development process. Nonethe-
less, Talbot’s recipe for “common photogenic drawing
paper,” which was not restricted by patent, continued
to be universally used until ca.1855 to make positive
contact prints from camera negatives; such positives,
then called “re-transfers” or “copies,” are today referred
to as salted paper prints. Thiosulphate-fi xation rapidly
became the preferred method, although Talbot himself
persisted in the use of halide (i.e., chloride, bromide, or
iodide) print-fi xation for some years, possibly due to an
aesthetic preference for the interesting colours that the
process generated, compared with the uniformly dull
brown of the thiosulphate-fi xed images.
The camera exposures for making photogenic draw-
ing negatives were lengthy—typically, one hour—dur-
ing which interval the sun moved relatively through
an angle of 15 degrees of arc; consequently, in any
sunlit scene, the areas of shadow were diminished and
their hard edges diffused, while the refl ections from
highlights were multiplied. Photographs printed from
photogenic drawing negatives often display a softness
of modelling that is quite different from the chiaroscuro
qualities seen in the much faster calotype process.
Talbot’s photogenic drawing negatives made in 1839–40
recorded the luminosity of his scenes with a delicacy
that is quite inaccessible to the instantaneous vision of
the human eye, and the modern camera.
Mike Ware
See also: Talbot, William Henry Fox; Herschel, Sir
John Frederick William; and Faraday, Michael.
Further Reading
Proceedings of the 1992 Conference, The Imperfect Image:
Photographs, their Past, Present and Future, edited by Ian
and Angela Moor, London: Centre for Photographic Conser-
vation, 1993.
Proceedings of the Photographic Materials Group Meeting, 1993,
Topics in Photographic Preservation, 5, 1993. Austin, Texas:
American Institute of Conservation.
Schaaf, Larry J., Out of the Shadows: Herschel, Talbot and
the Invention of Photography, New Haven: Yale University
Press, 1992.
——, Records of the Dawn of Photography: Talbot’s Notebooks
P and Q, Cambridge: Cambridge University Press, 1996
——, The Photographic Art of William Henry Fox Talbot, Princ-
eton, NJ and Oxford: Princeton University Press, 2000
Ware, Mike, Mechanisms of Image Deterioration in Early Pho-
tographs: the sensitivity to light of WHF Talbot’s halide-fi xed
images 1834–1844, London: Science Museum and National
Museum of Photography, Film & Television, 1994.
——, “Quantifying the Vulnerability of Photogenic Drawings,”
in Research Techniques in Photographic Conservation, edited
by Mogens Koch, Tim Padfi eld, Jesper Stub Johnsen, and
Ulla Bogvad Kejser, Copenhagen: Royal Danish Academy
of Fine Arts, 1995.
——, “Invention in Camera: the Technical Achievements of WHF
Talbot” in Huellas de Luz. El Arte y los Experimentos de Wil-
liam Henry Fox Talbot, edited by Russell Roberts, Madrid:
Museo Nacional Centro de Arte Reina Sofi a, 2001.
——, “Luminescence and the Invention of Photography: ‘A
Vibration in the Phosphorus’,” History of Photography, 26/1,
2002, 1–12.PHOTOGLOB ZURICH/ORELL FÜSSLI
& CO.
Photochromy is a lithographic printing process for
disseminating photographs via colour printing off
several stones, a combination of collotype and chro-
molithography for the production of “photolithographic
polychrome half-tone images.” The process consists of
the direct photographic transfer of an original nega-
tive onto litho and chromographic printing plates and
is most commonly known by its commercial name of
“photochrom.”
Whilst Lemercier had experimented with an analogue
process in the 1860s, and Vidal’s process enjoyed limited
dissemination in the 1870s, neither enjoyed commercial
success Breakthrough occurred in the mid-1880s when
a lithographer in Zürich, Switzerland experimented
with the process successfully enough for Orell Füssli
& Co., then a leading fi rm of banknote and map print-
ers, to decide to incorporate it into its development and
manufacturing plans. The fi rst photolithographic poly-
chrome half-tone prints produced by the fi rm in 1886
were always subsequently described as the fi rm’s own
invention, while the identity of the actual inventor was
never mentioned in the fi rm’s catalogues or other publi-
cations. The unheralded inventor was in fact Hans Jakob
Schmid (1856–1924), a lithographer from Nürensdorf.
He worked at Orell Füssli and Co. from November 1876
onwards, initially as a lithographer, then as a machine
minder. After an experimental phase, a patent applica-
tion was fi led for the new process in Austria-Hungary
on 4 January 1888.
Due to the business acumen of Heinrich Wild-Wirth
(1840–1896), partner in the fi rm since 1873 with his
brother Paul Felix, and, from 1890, chairman of the
board, the photochrom process was widely disseminated
and achieved unparalleled success in the market for
colour photographs. The trading company Photochrom
Zürich, founded in 1888 to exploit the process, incorpo-
rated the collotype printers and publishers Schröder &
Co. in 1895. The company thereafter traded as Photo-
glob Co. (since 1974 Photoglob AG) and is still active,
especially in the postcard business, as a subsidiary of
Orell Füssli Graphische Betriebe AG. The Photochrom
Co. Limited was established in London in 1896 as suc-
cessor to the London offi ce of Photochrom Zürich, set
up in 1893. An identically named subsidiary in Detroit
produced and marketed photochrom prints in America,