632632
HALE, LUTHER HOMAN
with or without colors, in a superior style, and neatly
set in Lockets, Pins, Rings, Bracelets, or Cases.” The
fi rm also sold daguerreian materials.
From 1850 to 1857, Hale continued at the same
address alone before listing G. A. Ayling as a partner
in 1858 and 1859. Hale also taught the daguerreotype
process and perhaps his best-known student was Wil-
liam Herman Rulofson, one of the fi rst great American
western photographers. He continued to be listed in
Boston through 1862.
Hale died in 1885 and his personal collection of fam-
ily daguerreotypes is preserved today at the American
Antiquarian Society in Worchester, Mass.
Bob Zeller
HALF-TONE PRINTING
Half-tone is a widely used photomechanical printing
process where a photographic image is translated onto
the printed page as a fi ne pattern of dots. The dot pattern
is so fi ne that the individual dots cannot be seen by the
naked eye. Rather the naked eye blurs the dot pattern
into an image that appears to have the quality of a photo-
graph. The dot pattern can be seen under magnifi cation.
Half-tone was an important invention as it provided an
effective process for commercial printers to mass print
photographically realistic images. Invented in the 19th
century it still commonly used today in commercial
printing. It is often referred to as the screen process or
dot process.
Before the half-tone process, the pages of newspapers
and magazines did not contain the photographically
realistic images that we take for granted today. The
most common type of picture in a newspaper was a
woodcut or wood-engraving. These prints, made from
hand carved blocks of wood, could not produce the
minute details and subtle tones of a photograph. While
often attractive, these prints more resemble hand drawn
sketches.
Since the invention of photography, commercial
printers wanted a practical way to realistically reproduce
photographs onto the printed page. The essential prob-
lem lay in the fact that the most common mechanical
printing processes can only print areas of ink or leave
blank areas on the paper. They could print different
tones. A newspaper press could only print black or
nothing. Photographs, on the other hand, have a range
of tone, meaning there are various shades of gray be-
tween black and white. This is what gives photographs
realistic images. While there were earlier mechanical
printing processes that could imitate the tone and subtle
details of a photograph, most notably the Woodburytype,
these processes were expensive, diffi cult to make, and
not practical for mass commercial printing that used
relief printing.
The half-tone process overcame these limitations,
offering a practical process that could create near pho-
tographically realistic images. The half-tone process
translates the tones and detail of a photographic image
into a printed pattern of tiny dots or similar marks. With
a magnifying glass these dots can be seen. Examination
of a photographically realistic picture in a modern news-
paper or magazine reveals the half-tone dots. Though
it was later applied to a variety of printing processes,
its initial triumph was that it could be applied to relief
printing, which was the staple of the book, newspaper
and other periodical industry.
The traditional half-tone process in relief is as fol-
lows: First, a negative is made by taking a picture of
the desired item through a special screen. Sometimes a
glass with crossed lines is used instead of a screen. The
screen breaks up the illuminated image into a pattern
of dots on the negative. The lightest areas of the object
create large dots close to each other. The darkest areas
of the object create smaller dots further part. The nega-
tive is then used to expose the printing plate that has a
photographically sensitive coating. The dots sizes are
reversed on the printing plate. This means that the largest
dots on the negative become the smallest on the printing
plate, and vise versa. The printing plate is developed,
the unexposed areas are washed away, and the plate is
etched. The fi nished printing plate has the dot pattern in
relief (raised from the rest of the plate). During printing,
ink is placed on the raised dots, which is translated into
a pattern of dots on the printed page. Depending on the
fi neness of the screen used, there will be more or fewer
dots per inch in the print. The more dots per inch, the
higher the quality of the image. On rough paper, such
as newspaper, fewer dots per inch are necessary. On fi ne
paper, more dots per inch are best.
The fi rst half-tone print in a newspaper appeared in- By the 1890s, many newspapers and magazines
had half-tone images.
Half-tone applied to intaglio printing is called pho-
togravure. Photogravure has a similar dot pattern, but
the ink is deposited in different amounts. In the dark
areas of the image, where the ink is the heaviest, the
ink is physically raised from the paper. This quality is
observed under a microscope. Photogravure could cre-
ate quality images, but not lettering. Half-tone could
be applied to lithography in the 19th century, but was
not widely used in commercial printing until the 20th
century. Today, most newspapers, magazines and other
commercial prints use lithography.
Color Half-tone. Half-tone printing is often tinted or
colored by printing solid colors onto the black half-tone
print. Sometimes, a black and white half-tone print is
hand tinted (2 additional colors) or hand colored (3 or
more colors). To make a true color half-tone, printing
plates are made, each for a different color. In the 19th