_PHOTO "PROCESS" ENGRAVING_--A PROGRESSIVE PROCESS--COMMERCIAL
AND ARTISTIC FEATURES--"LINE" PROCESS--"HALF TONE"--ARTISTIC
RESTORATION--TRI-CHROMATOGRAPHY--PHOTOGRAVURE
"It is not knowledge itself which is power, but the ability to
use and apply knowledge."
=A Progressive Process.=--Photo process engraving is a method of graphic
reproduction which comes into direct contact with art in its most
popular phases.
It is a distinctly progressive process which possesses immense
advantages and represents an effective and by no means inartistic aspect
of the graphic arts. The lavish, and in many instances extravagant,
employment of process engraving for purposes of pictorial illustration
is a substantial proof of its popularity and illustrative value. It
may not always reach a high standard of artistic realisation, but it
is almost invariably realistic and attractive in its varied forms of
representation.
The idea of pictorial illustration, whether as the translation of an
artistic conception or an actual representation of current events, has
ever been a fascinating one; and its evolution, from a photo-mechanical
standpoint, has been one unbroken record of remarkable progress.
To enter upon a detailed exposition of any of the many photo-mechanical
processes is somewhat beyond the purpose of this short treatise, and to
attempt anything but a full and comprehensive description on such lines
would be both unwise and valueless. Let it suffice, then, to indicate
their more salient points, their illustrative and artistic value, and
the manner in which they may be most successfully applied.
=Commercial and Artistic Features.=--The commercial advantages of
photo-engraving may be summed up in a very few words:--
1. The plates can be produced quickly and economically.
2. The impressions can be made at a high rate of speed, and in some
of the processes without perceptible deterioration.
3. The prints will be more or less facsimiles of the original.
From an artistic point of view, photo-engraving possesses equally
important features. It translates the artist's work with extraordinary
facility and accuracy, retaining a satisfactory proportion of its
expressive feeling, and reproducing subtleties of drawing and texture
which it would be difficult, if not quite impossible, to obtain by any
other process. Of the many photo-mechanical engraving processes, all of
which are more or less associated with pictorial illustration, three at
least merit further consideration.
[Illustration: Fig. 5.--Cross Section of Cyanide Furnace.
The "Line Process."]
(_a_) =The "Line" Process.=--The "line" process is applicable only to
the reproduction of line drawings or prints, in which the design is
represented in simple black and white, with only such gradations of tone
as may be suggested by lines or dots. For the reproduction of pen-and-ink
drawings, it has found considerable favour with illustrators, and many
even of the more conservative artists are compelled to appreciate
its merits and acknowledge its value. An interesting account of the
compulsory acceptance of process engraving by the famous illustrator
"Du Maurier" is suggestive of at least one valuable peculiarity of this
method of reproduction. Owing to failing sight, Du Maurier found it
increasingly difficult to introduce into his drawings on the wood block
that amount of detail which he considered necessary for the adequate
expression of his ideas. Eventually he was compelled to make pen-and-ink
drawings on a much larger scale than was his wont, and to have them
reproduced as photo-line-blocks, the reduction being made as required.
(_b_) =Half Tone.=--"Half tone" process engraving, as distinguished from
the "line" process, is the reproduction of a design or copy which has
in its composition gradations of tone in the form of flat tints. Wash
drawings and photographs present characteristic examples of such copies.
[Illustration: Fig. 6.--Process Engraving.
_Block by the Arc Engraving Co. Ltd., London._]
The true relative value of these medium or half tones can only be
retained in the half tone engraving by breaking up the picture into
most minute sections, and thereby producing a grain or series of dots
of varying size and contiguity according to the requirements of the
drawing. This grain or "screen" effect is produced by the interposition
of a network of finely ruled lines in the form of a screen between the
lens and the sensitive plate when photographing. The optical principle
involved is beyond the sphere of this work, but the effect produced is
a matter of vital importance, and requires careful consideration.
The coarser the ruling of a screen, consistent of course with the class
of work for which it is required, the more vigorous and consequently
more effective the reproduction will appear. The variety of tones will
be greater, and the textures will appear richer. Small prints are
naturally subjected to a close inspection; the screen effect, therefore,
should be less obtrusive than in larger ones. It may also be useful to
know that a finely ruled screen will reproduce the minute details of
a copy.
=Artistic Restoration.=--It is somewhat doubtful if the half tone
engraving, pure and simple, would ever have any real artistic value for
pictorial illustration but for some method of restoring those qualities
which are so considerably reduced when copying a picture through
the line screen. The pure half tone consists of a grain of varying
gradations over the whole design. There are, therefore, no pure whites
even in the highest lights. The use of the roulette and graver for
accentuating light and shade is therefore not only permissible but
decidedly advantageous, for the monotony of a mechanical grain is
thereby relieved, and the print produced will be an effective and
accurate translation of the artistic sketch.
"A true half tone will be best obtained by not relying entirely on the
mechanical means, but assisting them with some hand work, either in the
shape of re-etching or engraving, or both."
The application of hand engraving to photo-mechanical work has been
chiefly due to American process workers, who applied the technique of
the wood engraver's art to the amplification of their half tone blocks.
=Tri-chromatography.=--The "Three Colour Process" is more or less an
application of half tone engraving to chromo-typography. The colours,
each in their relative value, are produced by purely photo-mechanical
methods--the colours of the original copy being dissected by means of
specially prepared colour screens. Half tone blocks are made from each
of the three negatives, and superimposed in accurate register in the
subsequent printing, when, of course, the primary colours, red, blue,
and yellow, are used.
The process possesses brilliant and effective illustrative power,
offers ample scope for the ingenuity and manipulative skill of artist,
engraver, and printer, and promises well-nigh unlimited possibilities
as a medium of pictorial expression.
(_c_) =Photogravure.=--Photogravure may be very briefly described. It
is a photo-mechanical process, in which rich, soft tones of surpassing
delicacy and undeniably artistic effect are striking peculiarities.
Unlike "line" and "half tone" engraving, it is an intaglio process,
in which the printer as well as the etcher must possess a profound
artistic perception.
[Illustration: Reproduction by R. J. EVERETT & SONS' "INK-PHOTO" Process.
Plate ENGRAVING FOR ILLUSTRATION
WITHIN A MILE OF EDINBURGH TOWN.]
A polished copper plate is grained by dusting resin or asphalt powder
on its surface, and afterwards fixing it by the application of heat.
A _tissue_ negative print is made, squeezed on to the grained plate,
and developed in the usual way. The plate is etched through the tissue.
The action of the etching mordant--perchloride of iron--being in exact
proportion to the light and shade of the developed print.
The printing is a necessarily slow, and therefore costly, item.
This limitation to their production, however, enhances the value of
photogravure prints.
=Ink Photo.=--What is known as the ink photo process of reproduction
is interesting chiefly on account of the remarkable fidelity with which
engravings of the finest and most intricate texture can be reproduced by
its agency. It is essentially a photo-mechanical process, but differs
from others of a similar character, inasmuch as the vigour and
expressive power of the original is to a considerable extent preserved.
Colour values also, as far as they can be expressed by the engraver's
art (see p. 11), are reproduced by ink photo methods with surprising
accuracy, and the intensity of impression, that peculiar feature of
prints from engraved plates, is almost invariably well sustained.
A careful criticism of the appended illustration and frontispiece done,
this process will reveal many other interesting points of practical
value.