CIRE-PERDUE CASTING. - Casting, or pouring, is in general the operation carried out in sculpture to obtain the definitive work from the matrix mold, whether it is a matter of transferring the artist's first conception into another material, or of reproducing a work already executed. In the first of the two cases the casting process, called "lost-wax fusion," was the one used from the Renaissance almost down to the present day.
Around a support of refractory clay, the artist modeled the sculpture in wax, then coated it with a jacket of clay, also refractory, known as founder's clay, which solidifies easily. Once this double envelope, inner and outer, had been obtained, with the application of a great fire he let the wax melt, which flowed to the outside through suitable channels. Into the empty space, liquid metal, melted at high temperature, was poured through a hole at the top. The sculptures thus obtained, however, had considerable weight because of the great and irregular thickness of the metal inside. Later, once the practice arose of first forming the originals in clay and then transferring them into plaster, the artist coated the mold with a thin layer of wax and, continuing with the ancient process, succeeded in obtaining sculptures in which the metal was reduced to a thin, light sheet a few millimeters thick. The use of wax obliged the artist, in this second case as well, to model the work in its details, so that in lost-wax casting one can always speak of originals, since, even if several examples were drawn from a single mold, the artist was forced to execute the wax model each time.
This is not the case, however, in the modern process, called "a staffa" (with a clamp), which consists in pouring the metal between two envelopes prepared in advance, without the use of wax. This system, which allows many examples to be reproduced, does not have the merit of the first two and is more mechanical.
Cellini's description of the casting of the Perseus remains famous, and it can give an idea of the difficulties and the importance of the operation; and what Leonardo writes on the subject in mss. W, XI, XII and in the Trivulziano ms. is interesting; also of great interest is the treatise of the Sienese Vannoccio Biringuccio (1480-1539), printed for the first time in Venice by the publisher Curtio Navo in 1540.
Bibliography5 works
Giovanni Catandente