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from painting, drawing and printmaking and thus had
different attributes. With today’s sophisticated methods
of photo-manipulation, available by computer (now used
even in journalism!), to create once again fi ctions that
pretend to be real, contemporary photographers et al no
longer need to despise those who worked in the same
tradition in the 19th century.
In 1855 Alphonse Poitvin, regarded by many as the
father of gum printing, in an attempt to make more
permanent images than silver prints, published his
results of using various colloids, but it was not until 40
years later that the pigment process came into its own
when photographers wished to make images in a certain
way. The knowledge of the colloid process went much
further back than Poitvin: in 1798 Vauquelin, French,
knew the effect of bichromate as a sensitizer; Mungo
Ponton, Scottish, patented this in 1839; the French
physicist Edmond Bequerel had found that the size in
paper, when combined with a chromic salt, caused the
paper to become sensitive to light.
A sheet of paper is thus coated with gelatin or gum
arabic, mixed with pigment and sensitized with gum
bichromate. This emulsion hardens when exposed
to light and becomes insoluble in proportion to the
densities of the negative; called a gum bichromate or
photo-aquatint. Because the sensitizer is too slow for
an enlarger, negatives have to be the actual size of the
print and processed by contact printing. After exposure
any excess of unhardened emulsion is washed out and
the whole hardened further with sodium or potassium
bisulphate. All sorts of combinations are possible; using
several negatives, including drawn and painted ones,
and parts of cut negatives (to build a composition, as
in painting), various colours of pigment, together, or
one layer on top of the other, will produce the multiple
gum print. All can be fi xed to a variety of watercolour
and drawing papers. Because the process is restricted
to the translation of a few simple tones (whatever kind
of negative is used) and that the colour source is con-
tained within the emulsion, and has to be physically
coated onto the paper (usually by brush), the end result
can provide an equivalent texture and mark, including
brush stroke, pencil line, to that obtained by hand in
drawing and printmaking. It allowed therefore for a
similar method of working towards a fi nal image as
draughtsmen and printmakers enjoyed; parts could be
removed, added to, printed over, the tonal values altered,
so that, under a glass frame, it is often diffi cult to tell
if you are looking at a drawing, print or photograph. It
was thus also favoured by many who could not draw or
paint but wanted to. The main technical problem was
that of registration and often the result was that “out of
focus”—now called soft tone impressionism, became
merely a multi focus blur.
Because of the thickness of the dried emulsion the
colloid process lent itself to other adaptations. A gum
print could be formed on top of an initial platinum print
to produce the gum platinum (1902). Glycerine together
with various strengths of oxalate solution can be painted
on to deepen tones. The carbon print sat along side the
gum print and was also patented by Poitevin in 1855,
and perfected by Joseph Swan in 1864 by introducing
image transfer. Manufactured colloid papers using
carbon came in a variety of colours from red chalk to
dense green but could not be manipulated. They pro-
duced, however, the fi nest tonal range, accuracy and
most permanent images of all the colloid processes and
were seen as a more accurate and controllable form in
preference to the instability and diffi culty of obtaining
suffi cient control over tone than the gum print. Thus the
gum print had many similarities with other processes
that used a similar colloid system, such as the oil print
(or oil pigment process), also patented by Poitvin 1855,
and the oil transfer print, revived by G. E. H. Rawlins
in 1904 and also popularised by Robert Demachy. The
next developments included the bromoil print, bromoil
transfer and dye transfer.
In the end, whatever artists, photographers, thought of
the value of the results of the gum printing process—it
has to be said mostly disparaging then and now, the sim-
ple gum print, the practical applications of a sensitized
colloid, became a vital part of the development of the
printing industry.
Alistair Crawford
See also: Carbon Print; and Photogravure.Further Reading
Fredrick, Peter, Creative Sunprinting Focal Press, London,
1980.
Harker, Margaret, The Linked Ring. The Secession Movement in
Photography in Britain, 1892–1910, Heinemann, London,
1979.GURNEY, JEREMIAH (1812–1886)
Originally a jeweller in Saratoga, Gurney was one of
the fi rst to study photography under Professor Morse. In
1840 he moved to New York, where he opened a gallery,
sold daguerreotypes and offered portrait sittings. His
photographic gallery was the fi rst to open in America.
At his premises he taught numerous people, including
his more famous rival, Matthew B. Brady. He achieved
success in photographing society people, exhibited in-
ternationally and attended the Great Exhibition in 1851
at the Crystal Palace, London. He also won the coveted
Anthony Pitcher prize in 1883. In the 1850’s he broke
new ground by using mammoth daguerreotype plates,
and he constantly experimented with new photographic
methods, such as mezzo graphs. He worked with a num-
ber of people; for example, John Bishop Hall on the Hal-