the Maddox gelatin emulsion on glass of 1871, and
although its decline was precipitous after the 1930s,
it still can be found in some commercial products
used mainly in artistic photography.
Distinguishing a gelatin based paper from an
albumen paper is easy due to the fact that gela-
tin papers are usually thicker and have a baryta
(a compound of the element barium) layer, thus the
common name ‘‘baryta papers’’ applied to them.
This layer, placed between the paper base and the
emulsion, gives the paper an extra brilliance and
does not allow the paper fibers to be seen under low
magnification (20–40). Also they do not show the
general yellow-ochre color visible in the non-image
areas of albumen prints, nor the micro-cracks that
appear because of the scarce elasticity of albumen
to changes in humidity and temperature.
Collodion was used as a print emulsion from 1890
approximately until 1920. The technology was very
similar to gelatin papers, also incorporating a baryta
layer. In the 1910s and 1920s a variation called matte
collodion became very popular. The extremely matte
surface of these papers made them an economic alter-
native to platinum prints (platinotypes), and if toned
with platinum, they achieved the platinum print’s
characteristic gray-olive tone. Differentiating collo-
dion prints from gelatin prints is difficult, due to
their similar warm-gray tones; although with low
magnification, collodion papers commonly show
small abrasion marks that are less common in gelatin
due to the self-healing properties of the latter. This is
counterbalanced by collodion’s greater hardness that
acts as a barrier against oxidants, keeping them in
better condition than contemporary gelatin prints.
Another method of differentiating the two is to
place, in a non-essential margin area of the print, a
small drop of water and let it stand. Collodion is
highly waterproof so the drop is not absorbed, as
will happen relatively quickly with gelatin.
Silver gelatin POP papers were followed by DOP
papers that were much better adapted for use in
artificial light. In fact, the first DOP papers were
called ‘‘gaslight’’ papers because they were designed
to be exposed briefly under a gas lamp at maximum
illumiation, cleverly, later in the development pro-
cess the photographer reduced the gas supply, the
light turned more orange and as such could be used
as a safelight, which did not affect the paper. These
papers were based on a mixture of silver chloride
and bromide and offered slightly warmer tones than
the more neutral tones of later DOP papers based
on silver bromide, although through chemical ton-
ing it was possible to obtain other colors, one of the
most widely used being sepia, derived from sulfur
toning, that rose to great popularity in the 1920s.
Thanks to the industrial manufacturing of silver
gelatin papers, a wide variety of choices was initi-
ally made available to the photographer: from
glossy surfaces (obtained by drum dryers) to semi-
matte and matte surfaces (obtained by adding fine
silica powder to the emulsion), textures were also
applied to the baryta layer in order to imitate cot-
ton, silk, and other materials, plus a whole variety
of colored paper bases were also used. Catalogues
of the 1930s show a wide range of available papers,
that over the course of the century, have been
reduced to perhaps two or three types (grades) of
paper produced by each company, chiefly Kodak,
Agfa, and Ilford. As a consequence, many artistic
photographers returned to artisan processes that
allow them wider possibilities to control the texture
and color of their images.
Throughout much of the twentieth century, gela-
tin silver papers were generally produced in grades
that were differentiated by the length of exposure
required to achieve a full range of tones. So called
‘‘soft’’ papers, papers that required longer exposures,
achieve best results when printing from a high con-
trast negative. Well-exposed negatives are best
printed on normal papers, and when dealing with
an underexposed or ‘‘soft’’ negative, a ‘‘hard’’ paper
gives the greatest range of tones. Papers were also
graded by contrast, usually zero to five, from least to
most pronounced degree of contrast. Papers that
featured various surface textures (most commonly
matte, velvet, glossy, and high-gloss) and yielded
varying tones, from blue-black to warm browns,
were commonly available, as were papers in varying
thicknesses (most often single or double weight). At
the end of the century, very few specialized papers
for monochromatic printing were available; for
example, Kodak’s professional grade black-and-
white papers were multipurpose, and are capable of
developing as color prints with the application of the
proper chemicals.
Resin-coated (RC) papers were introduced in the
1970s to accelerate processing. Both sides of the
paper are coated with a plastic material to avoid
the absorbance of processing chemicals into the
paper base and facilitate the removal of fixer salts
in a much shorter time. Polyethylene and polyester
are among some of the common plastic materials
used. The conservation of some of the earliest RC
papers have been questioned after colored spots
appeared in some of them. Later papers seem to
perform more adequately, although it is recom-
mended to trim the margin areas to eliminate any
residual fixer that might have penetrated the paper
base through the side of the polyetylene-paper-poly-
etylene sandwich. Most museums and collectionsPRINT PROCESSES