Metal Sculpture: Polystyrene Patterns in Ceramic Shell Molds

Abstract

Sculptors and craftsmen have been fascinated for thousands of years with the possibilities and the enduring qualities of castable metals such as bronze and so am I. Since my earliest experiences with art, I have maintained an interest in the process of metal casting as a way of producing art objects. The two main concerns of a craftsman working with the process are the type of pattern and the kind of mold to be selected. For lack of a better material, patterns have been made of wax for at least 3000 years. The material for molds, however, has varied considerably, since sculptors relentlessly search for a better refractory material. The purpose of this report is to present the results of my experiences in using a plastic for patterns and a ceramic shell for molds. Ceramic shell, a relatively new type of mold-making material, provides significant advantages to sculptors. Compared with other types of investment molds, the ceramic shell mold is superior for producing small details and for its reliability in casting relatively small objects. On the other hand, the initial financial outlay for equipment and the need to give special attention to certain steps of the technique are much greater than for solid investment molds. After I had tried using many types of molds, I decided that ceramic shell molds are the most suitable for my purposes and I have used them exclusively during the past five years. Having made this decision, I turned to the problem of materials for patterns, which still concerns me. Incidentally, the process for constructing ceramic shell molds, which involves the application of several layers of silica (sand) with a liquid binder to a pattern, is described in Ref. 1.