line-block it may, perhaps, be thought that a drawing shewing the
finest detail cannot be reproduced in the text by a relief block made
by photo-chemical means. This is not the case; the swelled gelatine
process is such that at its best the very finest work can be so
reproduced. The method is not extensively used, chiefly owing to the
remarkable amount of skill required to produce the best results and to
the facts that the blocks take longer to make and are more expensive
than the ordinary line block. This, however, should not militate
against its use, for the increased cost is but very little, and the
longer time in making, say two days, should not be of any consequence
in a monthly or quarterly periodical. The great point in its favour is
its great fidelity as compared with the ordinary photo-chemical relief
blocks: for instance, a close cross-hatching reproduced by a line
block will often come out as a series of white dots owing to the fact
that at the points of intersection the black lines tend to thicken;
hence, on printing, the white spaces, instead of being sharply cut and
diamond-shaped, are rounded. This will not occur in a good block made
by the swelled gelatine method. Further, the process does not restrict
the draughtsman to dead black ink; the drawings may be made in pencil,
crayon, or in ordinary writing ink: it is even claimed that wash
drawings and photographs can be reproduced satisfactorily by this
method. In the case of pencil drawings, the best results will be given
when the surface of the paper used by the draughtsman is slightly
rough; a pencil drawing on Bristol board, for example, will not be so
well reproduced as one on ordinary smooth drawing paper. In brief, the
process is as follows: a photographic negative of the drawing is made,
and under it is exposed a bichromate gelatine plate. This plate is
then developed in water. As already described, the gelatine will swell
up in proportion to the amount of light to which it was exposed. The
"positive" thus obtained will be in relief, the high lights being at a
higher level than the shadows. A wax mould of the gelatine positive
is then taken, covered with a thin layer of plumbago and electrically
covered with copper. The "casting" so obtained is built up with metal
and then mounted on wood in the same way as a zinco or a half-tone.
The capabilities of the process may be judged by a study of Fig. 38,
which is an extremely faithful reproduction of a lithograph, by S.
Prout, by the swelled gelatine process.
[Illustration: Fig. 38. A Lithograph by S. Prout reproduced by the
swelled gelatine process.]
[Illustration]
COST
RELATIVE COST OF BLOCKS AND PLATES
The question of cost is one of very great difficulty; in all
probability no two firms will agree in their quotations for different
kinds of work, and the reason for this lies in the large number of
factors involved, many of which are very difficult to compute exactly.
With respect to line engravings, etching, mezzotint, wood cuts and
wood engravings, it is impossible to give any idea of the cost. It
depends entirely on the complexity of the subject and the artist
employed.
As regards lithographic processes for reproduction in one colour the
cost varies with the nature of the work. If an artist be commissioned
to make an autolithograph, the fee would be agreed upon beforehand.
Photolithography and collotype, on the other hand, are processes
which do not require the hand of an artist, and these methods of
reproduction are relatively inexpensive. The price quoted by the
lithographer or collotyper is for printing so many copies, hence the
relative cost per copy depends upon the run and on the quality of
the paper used. Lithography is cheaper than collotype; but if several
illustrations are sent at the same time to be reproduced by collotype,
the cost for each would be less than if sent separately.
In chromolithography a separate stone is necessary for each colour,
hence the cost depends upon the number of stones used, and as several
may be necessary to obtain a first-rate reproduction, it is obvious
that the process may prove very expensive.
Turning to photomechanical processes, the prices vary according to the
grade of work required--the best possible, good, and, lastly, cheap
work. By best possible is meant the best that can be made under
existing conditions, the price being immaterial; in good work the cost
will be a limiting but not a preponderating factor, hence the work
will be open to criticism; finally, in cheap work, the price is all
important, so that the result is a block or a plate which will print
well but which must not be criticized as regards its being a faithful
reproduction of the original.
It is obvious that in the last two cases the quality of the work will
depend upon the agreed price, whilst in the first case the cost will
depend on the amount of time and skill required.
It is obvious, therefore, that a comparison of cost cannot be made
between these grades; it is, however, possible to draw up a scale of
relative cost of the processes under consideration for work of the
same grade. In the table given below, A represents the best possible
work, B indicates good work, and C stands for cheap work. Since the
line block is the least expensive it is taken as the unit of price;
that is to say, if a line block costs 3d. per square inch the cost of
half tone, three colour half tone and photogravure would be 7-1/4d.,
3s., and 1s. 2-1/2d. respectively.
A B C
Line 1 1 1
Half tone and swelled gelatine 2-1/2 2-1/4 2
Half tone three colour (three plates
required) 9 12 10-1/2
Photogravure 4-1/2 4-3/4 5
It must not be thought that if the area of a block is 3 square inches,
the cost will, therefore, be 9d. There is, for obvious reasons, a
minimum size at which the block or plate is charged although it may be
smaller. These minima vary; in general terms they may be taken as 12
inches for line, half tone and swelled gelatine blocks, and 20
inches for half tone three colour blocks and photogravure plates. The
measurements are the areas of the etched surface, the actual plate or
block may be larger, but for this margin no charge is made.
With regard to cost of printing, nothing need be said about blocks
which are set up with the type, namely line, swelled gelatine and
coarse half tone blocks. The price of printing fine half tones and
three colour blocks depends upon the quality of the paper used and
the fineness of the work. Photogravure plates must be hand printed
(photogravure printing on rotary machines is not considered here), and
skill is required; for ordinary printing on good plate paper the
price would be 10s. to 12s. 6d. per hundred copies, whilst for India
printing the cost would be about 25s. for the same number.
LITERATURE
Barnes: _Illustrating Botanical Papers_, Botanical Gazette,
Vol. 43, 1907.
Bock: _Zincography_, London, 1910.
Cumming: _Handbook of Lithography_, London, 1904.
Cundall: _A Brief History of Wood-Engraving from its
Invention_, London, 1895.
Gamble: _Line Photo-engraving_, London, n.d.
Hamerton: _Drawing and Engraving_, London, 1892.
_Etching and Etchers_, London, 1880.
_The Graphic Arts_, London, 1882.
Pennell: _Lithography and Lithographers_, London.
Richmond: _Grammar of Lithography_, London, 1909.
Robertson: _The Art of Etching_, London, 1885.
Verfasser: _The Half-tone Process_, London, n.d.
Wilkinson: _Photo-mechanical Processes_, London, n.d.
* * * * *
Transcriber's Note
Some extraneous Headings on otherwise blank pages have been removed.
Each Footnote has been indented and placed beneath the paragraph to
which it refers.
The Plates, which were on un-numbered pages, and some of the Figures,
have been moved to (usually) below the paragraphs which first refer to
them.
page 35: 'revelant' corrected to 'relevant' ... "See also the relevant
works cited under Literature"
page 90: The Table of Costings does not appear to make sense, but has
been left as in the original.
Hyphenation is not consistent in this book.