Kinetic Art: Sculpture Displaying Strata and Changing Forms in Granular Materials

Abstract

The author's kinetic sculptures were inspired by his observations made while operating an air-track drill on the Alaska Pipeline construction project in 1975. Day after day he watched silica sand and other materials being blown out of drill holes and falling to form mounds having stratifications. The stratifications and the slope angles of the mounds are dependent primarily on such factors as the size, shape, roughness and density of the individual grains that form the mounds. This knowledge enables some understanding of the physical characteristics of the type of kinetic sculptures made by the author. The granular materials employed and the construction of the hourglass-type Plexiglas objects that contain them are described. The article concludes with general comments on this type of sculpture and the author's plans for future work. I. SCULPTURES OF GRANULAR MATERIALS: INITIAL CONCEPTION While working as an air-track drill operator on the Alaska Pipeline construction project in 1975, I spent many days drilling holes for pre-split blasting in granite bedrock. For hours I watched silica sand and other materials from the action of the airinjected carbide bit being blown out of the 7.6-cm diameter drill hole and landing in patterned piles on the ground. Visibility was barely three meters in the dust-choked air. The work was tedious, repetitious and dangerous, because the throbbing, compressedair concussion drill was perched precariously on a mountainside. This led me to concentrate even more intensely on the ground, where the only visible points of interest were the small, slowly growing mounds of drill-hole tailings. They became micro worlds whose formation I found hypnotic (Fig. 1). Delicate sliding patterns appeared out of the dust as the drill continued pounding the bedrock below. Time seemed to become compressed while I watched these miniature landscapes develop. I felt I was witnessing mountains and valleys being made. These forms, however, were not without cause: when sand is poured from an orifice onto a flat surface, it forms a cone with a characteristic angle with the horizon which is called the angle of repose. This is the slope angle that a pile of loose material assumes in order to remain stable. The angle of repose of a particular type must be determined empirically at the present time [1], since the actual *Sculptor, 514 East First Street, Moscow, ID 83843, U.S.A. (Received 8 March 1978) process is a complex physical phenomenon that is difficult to describe analytically. Among the factors that govern the angle of repose are grain size distribution and grain shape, roughness and density. My plans for sculptures in granular materials began on the mountainside. In the spare moments when I waited for the water truck to come to spray down the silica dust or during periods when the drill bit had become stuck and had to cool off, I dreamed of ways to present artistically the fascinating behavior of flowing materials and the resulting stratification patterns and formations. Months later, at the Carpenter Center for the Visual Arts at Harvard University my memories began to materialize. Fig. 1. Air-track drill at a construction site in Alaska, 1975.