Of Painting on the wall in Monochrome with various earths; how objects
in bronze are imitated; and of groups for Triumphal Arches or festal
structures, done with powdered earths mixed with size, which process
is called Gouache and Tempera.
§ 90. _Imitative Paintings for Decorations._
Monochromes according to the painters are a kind of picture that has a
closer relation to drawing than to work in colour because it has been
derived from copying marble statues and figures in bronze and various
sorts of stone; and artists have been accustomed to decorate in
monochrome the façades of palaces and houses, giving these a semblance
other than the reality, and making them appear to be built of marble or
stone, with the decorative groups actually carved in relief; or indeed
they may imitate particular sorts of marble, and porphyry, serpentine,
and red and grey granite or other stones, or bronze, according to their
taste, arranging them in many divisions; and this style is much in use
now-a-days for the fronts of houses and palaces in Rome and throughout
Italy.
These paintings are executed in two ways, first, in fresco which is the
true way; secondly, on canvas to adorn arches erected on the occasion of
the entrance of princes into the city, and of processions, or in the
apparatus for fêtes and plays, since on such structures they produce a
very beautiful effect. We shall first treat of the manner of working
these in fresco, and then speak of the other method. In the first kind
the backgrounds are laid in with potters’ clay, and with this is mixed
powdered charcoal or other black for the darker shadows, and white of
travertine. There are many gradations from light to dark; the high
lights are put in with pure white, and the strongest shadows are
finished with the deepest black. Such works must have boldness,
intention, power, vivacity, and grace, and must be expressed with an
artistic freedom and spirit and with nothing cramped about them, because
they have to be seen and recognized from a distance.[224] In this style
too must bronze figures be imitated; they are sketched in on a
background of yellow and red earth, the darker shades put in with
blended tints of black, red, and yellow, the middle tints with pure
yellow, and the high lights with yellow and white.[225] And with these
painters have composed decorations on the façades, intermingling
statues, which in this kind of work give a most graceful effect.
Those pictures however intended for arches, plays, or festivals, are
worked after the canvas has been prepared with clay, that is, with that
pure earth (terretta) before mentioned which potters use, mixed with
size,[226] and the back of the canvas must be moistened while the artist
is painting on it, that the darks and lights of his work may unite
better with the ground of clay.[227] It is customary to mix the blacks
with a little tempera;[228] white leads are used for the white, and red
lead to simulate relief in things that appear to be of bronze, and
Naples yellow (giallino) to put in the high lights over the red lead,
and for the backgrounds and the darks the same red and yellow earths and
the same blacks that I spoke of in connection with fresco work; these
make the half tints and shadows. The painter uses also other different
pigments to shade other kinds of monochromes, such as umber to which is
added terra verte and yellow ochre and white; in the same way is used
black earth, which is another sort of terra verte and the dark colour
that is called ‘verdaccio.’[229]