Los Angeles herald., 1892-03-05
BOOK ILLUSTRATION.
A LUCID EXPLANATION OF soME
DIFFERENT PROCESSES.

nov many OF tne ans sSsusos IN oOOkey
Magazines and Papers Are Produced.
The Dinsrencs Between Cheap and
Costly work Made Plain to Buyers.
with the increasing use Of half tone
work and the numerous processes for
hook illustration that have been devel-
pped or adapted during the past ten or
fifteen years, there has steadily grown
tendency on the part Of publishers, proc
ess men, and in some instances among
critics, to apply entirely inappropriate
names to the reproductions that are mis-
leading in the extreme and cannot but
do IN Injury to the better classes of work
by giving their names to processes much
thdlr interiors in quality.
Let us first consider the ordinary half
tone photoengraving Of which SO much
has lately been seen in the way of illus
trations for the higher class periodicals
and works Of an art and technical nature.
We shall find that these prints all render
the half tone Of the original; or, to be
less technical, show the various degrees
Of light and shade in masses of color.
differing in degree, but in fat tints, pro-
duced by breaking the original subject,
may have been either wash drawing,
painting in color, portrait from life or
view from nature, into and immense
number of dots, obtained by photograph
ing through the fine neshes of ruled
glass in manner not necessary Of de-
scription here.
The resulting picture is transferred to
the metal that is to serve as the finished
plate; the chemical action is proceeded
with and the half tone plate that results
shows the picture in relief and the en-
tire surface Of the plate a mass of fine
points or dots, separated by fine burrows
running in transverse directions, the
points in relief being the printing sur
faces. The plate being blocked on wood
or metal to render it Of the same height
as type, it is linked up with roller in
the Same manner that type is, and the
ink. adhering to the points, is impressed
into the paper that is brought in contact
with them in the printing press.
THE HALF TONE ENGRAVING.
It should here be noted that the points
or dots making up the printing surface
Of the plate, being all Of the same height,
the amount of ink deposited on the paper
IL of the same depth or thickness from
each and every printing point, and it
naturally follows that variations in the
light and shade making up the picture
are dependent on the number and size
Of such dots within given radius; thus
a heavy shadow in a picture printed
from relief plate will be seen to be COM
posed Of large number of these dots,
often 80 close together as to merge into
one another, while the high lights are
the result Of a preponderance of the
clear transverse lines that serve to sep
arate the dots more widely, only show
ing them sufficiently to give form and
color to their object.
The above are the principal points of
identification Of a print made from
half tone type plate in relief, and are
easily to be distinguished from pictures
produced from intaglio plates. There is
still another kind Of half tone relief
work, however, that Is not so easily dis
tinguished, and this is the photogelatine
or heiotype and kindred processes, which
in rendering the gradations Of color do
not cut them up into dots, but lay the
ink In smooth masses Of different tones
on the paper from a surface of gelatine.
PRINTING FROM AN INTAGLIo PLATE.
The photogravure is printed from an
intaglio plate, and is not capable of be-
ing used in type press under any con-
ditious. It can only be successfully
printed by an expert, and where with
relief plate the Office boy might "kick
of" say 1000 Q day, or the steam cylin-
der press 10000, the expert printer with
his intaglio plate would not produce
above 200 good impressions. The intaglio
plate Is filed while warmed with
hard, stiff ink, which Is pressed into
every depression, and after the high
lights Of the plate are carefully wiped
off," by hand, the plate Il run through
the press, in connection with the paper,
and the latter lifts from the sunken SUR
face Of the plate all the ink it has pre-
viously received, holding it on the sur
face Of the paper in masses Of color that
differ in depth and consequently in tone,
according to the depth of intaglio in diff
ferent parts Of the plate, the result Of
which is series Of graduations from
the pure high light Of the clear paper to
the rich, velvety black of solid body
Of ink spread over the surface Of the
paper and not pressed into it.
The grain, too, Of this plate, instead
OF being composed Of noticeable cross
hatchings Of lines and dots, is scarcely
discernible "tooth, that is obtained by
a peculiar chemical action on the
metal plate before the picture to be
etched is transferred thereto. Carbon
tissue being the medium through which
the transfer is made and the finished
print very closely resembling in most of
it's features that beautiful pigment, it is
q wonder that the feeling Of those in
terested in seeing justice done to all has
not been moro forcibly expressed on this
subject before.
A name that would answer the pur-
nose and still be meritorious, is the old
title photoglyph, as it applies to all
plates which give reproductions from re-
lief surfaces, while photogravure is
properly used only in the opposite con-
nection. Let all, then, who know bet
ter. be honest enough to call things
what they are and thus do what they
can to avoid further complication Of the
alraadv multitndinous collection of pro-