CHAPTER LIII

PAINTING. —WALL DECORATION
The inner walls of houses and public buildings at Pompeii
were plastered, and usually decorated with colors; only store-
rooms, kitchens, and apartments designed for the use of slaves
were left in the white. Outer walls were as a rule plastered,
except when built of hewn stone, a kind of construction not
employed after the Tufa Period. Stucco was occasionally used
on facades of ashlar work where special ornamentation seemed
to be needed, as at the entrance of the house of the P"aun; and
in later times, now and then, a front with reticulate or brick
facing was left unplastered. Previous to the time of Augustus
the stucco coating of outer walls ordinarily remained uncolored.
Afterwards color was employed, but only to a limited extent,
as in the addition of a dark base to a wall the rest of which
remained white.
The painting upon Pompeian walls, as shown by the pains-
taking investigations of Otto Donner, was fresco, that is, exe-
cuted in water colors upon the moist stucco of a freshly plastered
surface. The method of preparing the wall was less elaborate
than that recommended by Vitruvius, who advises the use of
seven coats of plaster, first a rough coat, then three of sand
mortar and three of stucco made with powdered marble, each
coat being finer than the one preceding. In the better rooms,
however, we find upon the walls at least one, often several,
layers of sand mortar, and one or more coats of marble stucco;
the entire thickness of the plastering varies from two to three
inches. In unfinished or neglected rooms walls are sometimes
found with a single coat of sand mortar. Occasionally powdered
brick was used in the stucco as a substitute for marble dust.
Plastering so thick as that ordinarily used must have remained
moist for a considerable length of time, much longer than the
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