This is the art of printing, by a chemical process, from designs made
with a greasy material upon stone. It was discovered about the beginning
of the present century by Alois Senefelder, an actor of Munich,
Bavaria, whose patience and perseverance under the most disadvantageous
circumstances were truly remarkable and praiseworthy. Differing from all
other methods of printing, the impressions are obtained from a level
surface.
The stone best calculated for lithographic purposes is a sort of
calcareous slate found on the banks of the Danube, in Bavaria, the finest
being found near Munich. A good stone is porous, yet brittle, of a pale
yellowish drab, and sometimes of a gray neutral tint. The stones are
formed into slabs from one and a-half to three inches in thickness. To
prepare them for use, two stones are placed face to face with some fine
sifted sand between them, and then are rubbed together with a circular
motion, to produce the requisite granulation, which is made finer or
coarser to suit the purpose of the artist.
The principal agents used for making designs on stone are called
lithographic chalk and lithographic ink. They are composed of tallow,
virgin wax, hard tallow soap, shellac, sometimes a little mastic or
copal, and enough lampblack to impart a colour to the mass. These
ingredients are put into an iron sauce-pan, and exposed to a strong fire
till the mass is in a state of ignition. When the quantity is reduced
one-half, the pan is carefully covered, or put into water to extinguish
the flame and cool the mixture. After being well worked up, it is formed
into small cakes or sticks. The ingredients are the same in the chalk and
the ink, but the proportions are varied, and a little Venice turpentine
is often added to the latter. The chalk is used in a dry state; but the
ink is dissolved by rubbing in water, and is used in a pen or with a
camel-hair pencil. The presence of soap renders it soluble in water.
The artist completes a drawing with the chalk upon a grained stone as
he would make a drawing in pencil or chalk upon paper. If while in this
state a wet sponge were passed over the face of the stone, the drawing
would wash off. To prevent this, and to make it capable of yielding
impressions, a weak solution of nitrous acid is poured over it, which
unites with and neutralizes the alkali or soap contained in the chalk,
and renders it insoluble in water. After this, the usual course is to
float a solution of gum over the whole face of the stone; and, when this
is taken off, the drawing is no longer removable by the application of a
wet sponge, because the chalk is now insoluble. The stone is now ready
for the printer, who obtains impressions by the following process.
Having damped the surface of the stone equally with a sponge filled with
water which has been slightly tinctured by acid, the printer finds that
the water has been imbibed by only those parts of the stone which are
not occupied by the drawing, which, being greasy, repels the water and
remains dry. A roller covered with ink is now passed over the stone,
which will not even be soiled where it is wet, from the antipathy of oil
to water. But the parts occupied by the drawing, being dry and greasy,
have an affinity for the printing-ink, which, therefore, leaves the
roller and attaches itself to the drawing. In this state it is said to be
charged or rolled in. A sheet of damped paper is then put over it, and,
the whole being passed through a press, the printing-ink is transferred
from the stone to the paper, and the impression is obtained. Great nicety
is requisite in the preparation of all the agents employed in this art,
and in the process of printing as well as in making the drawing on the
stone.
The most important application of this process is in the production
of copies of coloured drawings and paintings,—a process known as
_chromo-lithography_. The object here being to produce as nearly as
possible fac-similes in colour, touch, and texture, as well as in
drawing and light and shadow, of pictures from the pencils of painters
of the highest standing, it has been found necessary to employ a large
number of stones, in order to produce the almost infinite varieties of
tints which are found united in a single picture,—every stone giving
a separate impression in its own particular colour or tint. The mode
of procedure is somewhat as follows. First, an outline of the entire
subject is made by means of transfer paper, or otherwise, on a stone
which is called the outline or keystone of the work. This stone yields
impressions which are transferred as guides to all the other stones. On a
second and third stone which serve as the basis of the print the general
effect of the drawing is washed in, and from these are printed what may
be called the chiaroscuro, in a faint tint of sepia and of a neutral
colour or gray,—corresponding, in fact, very nearly to the neutral or
dead colouring of a water-colour drawing in the method adopted by the
early water-colour painters. The stones which follow are each charged
with a particular colour or tint, and each leaves its impression on only
a particular portion of the print,—one stone printing only the parts
which are intended to be yellow or a modification of yellow, another
red, another blue, and so on. Other stones charged in parts with grays
or secondary colours serve to blend and harmonize the crude colours;
others follow which modify these; and, finally, one gives the sharp dark
touches, and is usually followed by another which supplies a sort of
glaze or finishing wash, and subdues and harmonizes the whole. Of course,
we have merely indicated the general method. It will be understood that
the sequence of the colours in the printing, the special quality and
strength to be given to each particular tint, the effect to be produced
by their super-position, and many other particulars, have all to be
taken into account in planning the arrangement of the colours on the
stones;—since a sequence in some respects different, and an entirely
different modification of colours, have to be employed for the works
of most artists; and it happens that much of the colour on each of the
earlier stones is covered by that of succeeding stones, and that thus
only can the broken tints of the original be imitated. It is, in fact,
only by watching the progress of a print through all its stages that
any clear idea can be obtained of the beauty and accuracy of the whole
process, of the prevision that must be exercised, and of the skill, care,
and taste required at every step to carry it to a successful termination.
For some of the more elaborate prints, from thirty to forty stones have
been required to produce a finished print. And in order to produce this
print, it must be borne in mind that each sheet of paper has to be
passed as many times through the press as there are stones, since each
stone imprints upon it only its own particular section of the work. Of
course, in proportion to the increase in the number of the stones, does
the difficulty increase of making the work upon each fall exactly upon
its proper place in the general design; for, if any one were misplaced
only the fiftieth of an inch, the drawing and colour of the whole would
be disturbed. Hence it is found necessary to arrange the _register_, or
adjustment of the stones, with the utmost care and precision, and to
exercise the most careful supervision in the printing, since the sheet
of paper expands considerably in passing through the press, and has
to be dried and re-damped before it can be passed through again. But
practically this is all accomplished with seeming ease, and a large and
most complex subject will be found, when the last stage has been reached,
to bear the most minute scrutiny; and the result, even when the copy is
placed alongside the original, will surprise and delight equally those
who have followed the work through its several steps and those who may
only examine the completed work.
Of late, many chromos have been beautifully printed from prepared blocks
on an ordinary cylinder-press.