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INTRODUCTION
A
photomechanical print is not a photograph, but a mechanical print that
can look like a photograph. A photograph is created by the subtle
interaction of chemicals and sunlight or other radiant energy. A photomechanical print is created by
pressing a printer's plate with ink down onto the printing
surface. A photomechanical print
may look photo-realistic from a distance, but close inspection reveals
that it often lacks the subtle detail of a photograph. Photomechanically produced images
became popular in the 1880's, and are regularly used today to make
pictures for newspaper, magazines, posters and advertising.
THE HALF-TONE PROCESS: DOTS NOT DASHES
Before the invention of the half-tone processes in
the 1870's, it was not possible to mechanically print photo-realistic images.
It was only possible to make mechanical images with lines. This would create attractive image,
but without the subtle shades of a photograph. If you see the pictures in a
newspaper or book from this period time, you will see that the images
look, at best, like fine drawings.
The
invention of the half-tone
process replaced lines with dots.
This allowed for much finer detail. While the half-tone didn't always
produce the quality and detail of a real photograph, it can make a good
representation. If you look
closely at a picture in today's newspaper you will see that it is made
up of tiny dots. The smaller and
closer together the dots, the more detailed the image.
The
following is a description of the major photomechanical process. Of these, the collotype and
Woodburytype did not use the half-tone process. While photomechanical prints are
collectable, they must be distinguished from a photograph.
All
of the described processes could produce a print of any color,
including a mimic of a photograph’s color.
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COLLOTYPE
Identification
The collotype process was versatile and produced
high quality images on many types of paper. Some examples can be difficult to
distinguish from a photograph.
Under
the microscope, the image detail is reticulated, which means that it
appears like a mosaic with similar size suiggles of irregular
shapes.. The size of the
reticulation varies from print to print, but cannot be seen by the
naked eye. Some collotypes were
varnished, making it difficult to see the reticulation even under
magnification. The image can be
a variety of colors.
Overview
Many early postcards (often with ‘Albertype Co.’
printed on back), and 1920s movie lobby cards were collotypes.
100X view
of collotype 1920s movie lobby
card
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PHOTOGRAUVE
Identification
This process is known for its excellent image
quality and detail. The surface
is matte and the image can come in any color. The print was created by using
heavier ink to create the dark image areas and less ink to create the
light areas. Great pressure was used to squeeze the ink onto the paper,
and plate marks may exist on the paper.
This appears as an embossed line a distance away from the
image. Sometimes this mark was
trimmed off of the print. Some
cheaper prints added a faux plate mark to make the print look
fancy. The photogravure images
do fade like the albumen, salted paper or silver-gelatin prints. They can become brittle and have some
foxing or discoloration.
Under
the microscope, a irregular grain pattern exists which is unlike the
subtle tones of a photograph.
The inks is rather speckled, and is broken into a fine,
irregular pattern known as a aquatint grain. This is best seen in the highlighted
areas. The ink seems to rest on the paper fibers instead of being
imbedded in it. A variation of
the photogravure called the rotary
photogravure was produced on a cylinder. The ink on the photogravure image is
set up in an even grid, with dots on ink surrounded by intersecting
white lines. This is a similar
pattern to the photoengraving and photolithography. The rotary photogravure,
however, produces dots with soft edged and are too small to see with
the naked eye.
Overview
The photogravure was invented in the late 1870's
and was used throughout the 20th century. It is noted for its excellent
reproduction of detail. It was
traditionally used for quality book and magazine illustrations and
topographical views.
Alfred Stieglitz 1911 Photogravure published in his
famous magazine, ‘Camera Works.’
This was made from the original photographic negative, and
Steiglitz considered the resulting print to be an original.
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PHOTOENGRAVING
Identification
The photoengraving process creates an image with a
grid-like pattern of dots. In
the dark areas of the image, the dots are larger and closer
together. In the light areas,
the dots are smaller and further apart.
The edges of the dots are sharp.
The overall image is of poor quality as compared to the some
other photomechanical prints.
Photoengraving was usually used for mass and cheap prints, such
as newspapers or magazines pictures, and are usually on low quality
paper stock. The images were
usually included with text, border lines and other design. This text and lines will be
completely solid under magnified inspection.
Most
photoengravings are black and white, though other colors are possible.
The finer the surface of the paper, the more detailed the image. The photoengraving was introduced
into popular use in the early 1880s and is still used today.
Overview
The photoengraving was popular from the 1880s until
1960s. Many early postcards,
trading cards and newspaper pictures were photoengravings.
Half-tone engraving from a 1950
Magazine Premium on glossy paper, showing the mechanically made rim.
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WOODBURYTYPE
The Woodburytype, called photglyptie by the French,
is capable of high quality images.
They are nearly identical in visual appearance to the carbon
print (see chapter 4). Even
under the microscope, the woodbuytype has nearly photographic
detail Unlike the dot or screen-like
patterns of other photomechanical processes, the Woodburytype has the
continuous tone of photography.
This is the only photomechanical process that did not use the
half-tone process. The
Woodbury-guavre is a closely related process. These prints are often easy to
identify because ‘Woodburytype’ or Woodbury-guavre’ is printed just
below the image
While nearly identical in
appearance to the carbon print, a few clues can give it away. Firstly, the woodburtype often has a
more prominent image relief than carbon prints. The shadow areas are
glossy and have a stronger relief effect. Most woodburtypes were used as book
illustrations, and cannot be larger than 11" by 14" The
carbon prints can be much larger.
As Woodburytypes were often used in books, they often will have writing
or border lines on the same page.
They sometimes appear as cartes de visite or cabinet cards.
The
Woodburytype suffers from similar aging patterns as the carbon
prints. The image rarely
fades. The print often gets
brittle and is susceptible to cracking.
If unmounted it has a tendency to curl.
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