University Missourian. [volume] (Columbia, Mo.) 1908-1916, 1915-06-15
HOW NEWSPAPER CUTS ARE MADE
Zinc Line Etchings and Halftones Are the
Results of an Interesting Process in
Photo-Engraving

III -
The making of cuts for the maga-
zines and newspapers is more than
photography, for the printer must
have a surface with relief from
which to print; it is photo-engraving.
Under any name, it is an interesting
process and not nearly so complicated
as one might think.
Newspaper illustrations are usually
of two kinds-zinc line etchings,
made from pen drawings, and half
tones, made from photographs and
other copy" with tones between
black and white.
In making the zinc line etching, the
original pen drawing is first photo
-graphed upon a sensitized plate of
glass. When the plate is developed,
the image is printed through the glass
plate on a plate of sensitized metal
After this exposure the plate is COW
cred with a coating of ink. 1t is
then put in water. and the compost
| tion of the material on its face is
such that all the parts upon which
the light shOne remain with the top
coating of ink, while the material is
washed away in other places. Since
the light shone on the metal plate
wherever there was line or mark on
the glass plate-these being the trans
parent portions of the negative-the
lines and marks appear on the metal
plate.
Spaces Cut Away With Acid.
These are the parts that will print.
The spaces between the lines are cat
away with acid. leaving the lines and
marks raised above the surface.
In making a halftone the problem
is somewhat different Lines and
white space cannot be relied on to
show the tints or shades of picture,
so there must be cut that will leave
only little ink in one place and
different amount in another - rep
resent the different tones of tho pic
ture This shading is obtained in the
printed halftone by minute dots and
white space. 1t is the problem of
the engraver to make these dots of
such relative size that the s.,adirs =
will correspond to that OF The pic
ture.
How are these dots madea The pic
ture is photographed through AL en-
graver's screen that breaks up the
| light into little dots. This screen is
not screen in the ordinary sense, but
consists of two pieces of glass on
which parallel lines have been ruled,
running in one direction on one glass
and at right angles on the other. The
two pieces of glass are struck together.
The lines are ruled on the glass
plates. There are 100 to the inch
for the screen used in making cuts
for the University Missourian. The
lines run diagonally across the
screen so that the rows of dots in
the printed picture will be less con-
spicuous.
Success Depends on Dots.
The success of the process depends
upon how the dots grow in size as the
exposure continues. If the plate
should be given one long exposure
the dots would be too large in the
white spaces of the picture and too
little in the dark places. Where there
are extremely dark tones in picture,
it is necessary to photograph piece
of white paper for time. This ca1s
es a uniform growth of small black
dots all over the plate.
When the picture is exposed, the
dots grow faster on the part of the
negative corresponding to the light
portions, and very little in the parts
corresponding to the dark places. The
picture is given two exposures with
different amounts of light allowed to
reach the sensitive plate through the
lens.
This light causes black dots to form
on the halftone negative by acting on
the silver nitrate that has been used
on its face In the parts correspond
ing to the light parts of the picture
there will be large black dots on the
negative. These dots will grow in
size during the exposure until they
join at the corners. This joining of
the dots at the corners is always
sought by engravers.
Printed on q Metal Plate.
When the plate has been developed