MURAL DECORATION--SYSTEMS AND METHODS
Various processes, systems, or methods have been employed in ancient and
modern times in the colour decoration of walls and ceilings. Under this
section of art is included all kinds of wall paintings, from the
representation of the symbolic hieroglyphics, found in the Egyptian
tombs, to the monumental paintings on the walls of public buildings,
churches, and palaces. The decoration of wall surfaces in colour is one
of the very oldest forms of art, and to a wall painting of any kind the
term “fresco” has usually, but somewhat loosely, been applied. Strictly
speaking, however, a veritable fresco painting is one that is executed
on the fresh or wet lime plaster of the wall, and is not re-touched
after the plaster has become dry. All other varieties of so-called
“fresco” paintings can only be designated as wall paintings, and
qualified according to their kind, such as “fresco-secco,” or “dry”
fresco, a kind of fresco where the wall is prepared in the same way as
in true fresco, and is then allowed to dry. Before the painting is
commenced, the wall is well saturated with lime water, and the colours
used are the same as those employed in fresco painting. It is not so
permanent as work executed on the fresh, wet plaster. Some of the old
writers frequently use the term “secco” when tempera painting is
evidently meant. Painting in _tempera_ on the dry wall is a process in
which the colours are tempered with a binding medium, such as glue size,
gum, parchment size, or a size made from eggs beaten up with water; the
Italian painters added the juice, or gum, of the fig tree, and sometimes
vinegar to the egg size. Other methods are _encaustic_, or painting with
wax as a medium, heat being afterwards applied to the wall to blend or
to protect the colours; _spirit fresco_, in which the colours are ground
in a wax medium and thinned with spirits of turpentine or oil of spike;
_water-glass_, a German method of wall painting; Keim’s process, an
improved variety of water-glass, and wall painting in oil colours.
The only advantage that these varieties of wall painting seem to possess
over the _buon_, or true fresco, process--and it may be considered as a
questionable one--is, that as regards the number of the colours, the
artist may use an almost unlimited or unrestricted palette, while in
buon fresco his colours are limited to the very few which remain
unchanged when subjected to the caustic action of the lime in the
plaster. Tempera painting on walls has been so much mistaken for the
fresco process that it is impossible to say when the latter was first
practised, but according to the statements of Vitruvius and Pliny, the
process was well understood by the Greeks and Romans. Perhaps one of the
most interesting revelations in the history of the art has been brought
about by the discovery of several fragments of wall and ceiling
decorations, found recently by the late Dr. Schliemann during the
excavations of the ancient cities and palaces of the pre-Hellenic Mycene
and Tiryns, of primitive Greece. One of these fragments of fresco
painting, which was found in a palace at Tiryns, consisted of a portion
of a wall or ceiling, a stucco slab, composed of lime and sand plaster,
on which is painted the representation of a spirited bull with the
figure of a man vaulting over its back. This interesting piece of work
must have been executed at least as early as 1500 B.C., as the city of
Tiryns was a mass of ruins shortly after this date. Many other fragments
of fresco paintings have also been found in the ruins of these ancient
palaces, some of which were decorated with linear and geometric
ornament, conventional flowers, and animal forms. Not only were the
walls and ceilings decorated with frescos, but the floors of some of the
apartments were treated in a similar manner. Still earlier examples of
fresco painting have been found in prehistoric Thera, one of the Grecian
isles, and others in the Minoan palace at Cnossus, in Crete, both of
which may have been painted as early as the nineteenth century B.C., and
certainly not later than the eighteenth.
The wall paintings of the Egyptian tombs were
[Illustration:
[_To face p. 10_
PLATE 2.--FRAGMENT OF ANCIENT FRESCO FROM TIRYNS]
executed in tempera on a gesso or stucco white ground, the same method
being followed in the decoration of the mummy cases and other objects.
In some instances these tempera paintings of the Egyptians were
varnished, which was not an advantage to their appearance, as the
varnish darkened, and in a great measure destroyed, the beauty of the
original colours.
Some of the wall paintings found at Pompeii are said to have been
executed in veritable fresco, since lime has been found in mixture with
most of the colours used. On the other hand, this has been disputed, and
some authorities classify them as tempera or secco paintings; but
perhaps the truth of the matter is, that a certain amount of the first
colouring was really executed on the wet lime plaster, and that, in some
instances, certain colours, used in the finishing of the work, were
applied afterwards in a tempera medium when the wall surface had become
quite dry. This method of procedure, according to the statements of
Vasari and Cennini, was not an uncommon practice with the Italian
_frescanti_ of the fourteenth and fifteenth centuries.