“It happened lately that my breast and back were covered with pitch by
the _sculptors in bronze_, and a ridiculous cuirass was thus formed
on my body, and by imitative art received a complete seal from the
brass.”[24]
This passage is supposed to indicate the process of casting in plaster.
It is possible that it may indicate a preparation in pitch to cast
in bronze, but certainly not in plaster, which is the sole question.
It is not workers in plaster who are engaged on it, but workers in
bronze; and what they were doing was plainly to take impressions of
the intaglio chasing or engraving on the body of the figure. The
description of the bronze is that it was archaic, and beautifully
traced and engraved. It may have been a term engraved with verses, or
figures, or inscriptions; and this is by no means improbable, as it
represented Hermes, and as nothing but the breast and back was covered
with pitch. At all events, the process was one which seems to have
been carried on, not for once, but daily. It may have been the famous
Hermes ἀγοραῖος, which was cast in the 34th Olympiad, and was a study
for brass casters. Again, it may not have been a figure in the round,
but merely a bas-relief, or intaglio; and this supposition would be
entirely in accordance with the hieratic and archaic sculpture in
brass, marble, and terra cotta. Many were executed thus in intaglio and
engraved,—some of which still remain,—and others in relief. A list of
such may be found in Müller’s “Ancient Art” (pp. 61–65). If the passage
refers to making a mould for casting, it was for casting in bronze and
not in plaster, though nothing is said about casting, but merely of
taking impressions or seals. The words ἐκτυπούμενος and ἐκματτόμενος
mean ex-pressions from a seal or stamp. Exactly what the sculptors were
doing, however, to this statue covers the process of brass casters.
Thus Lucian, speaking of a certain brass statue in the Agora, says:
οἶσθα τὸν χαλκοῦν τὸν ἑσῶτα ἐν τῇ ἀγορᾷ, καὶ τὰ μὲν πιττῶν τὰ δὲ εὔων
διετέλεσα,—“You know the brass statue standing in the forum, on which I
was occupied pitching and drying,” or burning.
But there is nothing new in all this, and nothing which throws any
light upon the subject in question. It was, as we well know, a common
practice of the Greeks, in making their large statues, to build up a
core of wood, brickwork, plaster, and other materials as a foundation
or rough sketch. On the surface of this in their chryselephantine
statues they veneered sheets of gold and ivory, sometimes covering the
entire surface with these precious materials, and sometimes finishing
portions of them with an exterior of plaster or clay, which was painted
in imitation of life. This for instance was the case with the Dionysos
in Kreusis, described by Pausanias, of which the whole figure was
modeled in plaster and afterwards colored. It would also seem to have
been a practice with the Greek artists to cover these roughly executed
cores with a composition of resin and pitch which they indurated by
fire; and afterwards to finish the surface in the same material. Such
at least appears to be the process indicated by Lucian in the passage
just quoted, in which he speaks of the statue he was engaged in
pitching and drying; as well as by Apollodorus in a passage in which
Dædalus is described as making a statue of Hercules in pitch (πίσσα).
The term “pissa” in this last passage has by some translators been
supposed to be a misprint for ἐν πίση, meaning that this statue was a
ζόανον executed in pine wood like other Dædalian figures. As it stands
in the original, certainly, it is πίσσα, and means pitch; and it is
quite as probable that it is correct and means a sort of encaustic
finish with resin and gum. However this may be, there is little doubt
that in making their bronze statues the Greeks used a surface of wax
and pitch, or some such material, which was plastic and would melt; and
it is well known that they spread wax over their statues to give them a
polished surface, and also finished their plaster walls with a covering
of wax.
In making large statues, a skeleton framework of wood was often
employed, called κίνναβος, or κάναβος, which was covered with solid
material,—clay, plaster, brick, pitch, etc., all welded together to
form a solid core over which the surface was finished in clay, plaster,
pitch, ivory, or gold. In the “Somnium, seu Gallus” of Lucian, Gallus
says, speaking of himself, “If he were king, he should be like one of
the colossi of Phidias, Praxiteles, or Myron, which though externally
like Neptune or Jupiter,—splendid with ivory and gold, bearing the
trident or the thunderbolt,—yet if you look inside you will find them
composed of beams and bolts and nails traversing them everywhere, and
braces and ridges, and pitch and clay, and other ugly and misshapen
things.”
It is a curious fact bearing generally on this subject that no allusion
is ever made to such a person as a caster in plaster. Plutarch,
enumerating the various trades and occupations to which the great
public works of his time gave employment, speaks of operatives,
modelers, brass-workers, stone-workers, gold and ivory workers,
weavers, and engravers, but never mentions a caster. Philostratus
also, enumerating the different classes of workmen in the plastic art,
makes no mention of casters. Pliny never speaks of them. Indeed, their
existence is never mentioned by any ancient writer.
All things considered, then, in conclusion, it seems impossible to
believe that Pliny intended, in the passage relating to Lysistratus, to
declare that he invented any method of casting in plaster, but rather
that he intended to say that Lysistratus either modeled likenesses in
wax over a core of gypsum, or, what is much more probable, that he
colored his likenesses in imitation of life; and that his specialty was
making accurate and literal likenesses in the round with color, thus
uniting the two arts of the painter and the sculptor.
The process of casting in plaster, in our acceptation of the phrase, is
of modern origin, and so far as we know was invented in the fifteenth
century, a little before the time of Verrocchio (1432–1488), the master
of Leonardo da Vinci. He was among the first who employed it, and may
fairly be said to have introduced it. At all events, the first clear
mention of this process of which we are aware is by Vasari in his life
of Verrocchio; and he states that this sculptor and painter “cast
hands, knees, feet, legs, even torsi, in order to copy them at his
leisure; and that soon after casts began to be made from the faces of
persons after death, so that one sees in every house in Florence, on
mantel-pieces, doors, windows, and cornices, a great number of these
portraits, which seem alive.” For some time after it seems to have been
used chiefly for taking casts from dead faces,—or hands and feet,—and
not to have been applied to casting from models of clay. The general
practice of that period was to make a small model in clay, then to bake
it, and from this model by proportional compasses to enlarge it and
point it upon the marble. The process of casting from clay models seems
not to have been practiced then, and so far as we know models of full
size in clay were rarely if ever made, until rather a comparatively
recent period.