CHAPTER XI. (XXV.)
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]]