GETTO (FUSIONE A CERA PERDUTA). — The g., or casting, is generally the operation performed in sculpture to obtain the finished work from the matrix mould, whether it involves transferring the artist’s initial conception into another material or reproducing a work already executed. In the first of these two cases, the procedure known as “lost-wax casting” was the one used from the Renaissance almost to the present day.
Around a support of refractory earth, the artist modelled the sculpture in wax, then covered it with a casing, also of refractory earth, called foundry earth, which solidified readily. Once this double inner and outer casing had been obtained, he used a large fire to melt the wax, which flowed out through suitable channels. Molten metal, melted at a high temperature, was poured through an opening at the top into the empty space. The sculptures thus obtained were, however, considerably heavy because of the large and irregular thickness of the metal within. Later, when the practice arose of first forming the originals in clay and then transferring them into plaster, the artist covered the mould with a thin layer of wax and, continuing with the ancient procedure, succeeded in obtaining sculptures in which the metal was reduced to a thin, light sheet only a few millimetres thick. The use of wax also obliged the artist in this second case to model the work in its details, so that in lost-wax casting one can always speak of originals, since, even if several specimens were taken from a single mould, the artist was obliged to execute the wax model anew each time.
The same does not occur, however, in the modern procedure, called “flask casting,” which consists in pouring the metal between two casings prepared in advance, without the use of wax. This system, which makes it possible to reproduce many specimens, does not possess the merit of the first two and is more mechanical.
Cellini’s description of the casting of the Perseus remains famous, as it can convey an idea of the difficulties and 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 by the Sienese Vannoccio Biringuccio (1480–1539), first printed in Venice by the publisher Curtio Navo in 1540.