Jessica Plant, University of Cambridge
This paper explores the semantic and infrastructural dimensions of plaster in antiquity. As an artificial composite, plaster was a mixture of earth, fire, water, and air. Labourers manufactured plaster by firing limestone or marble to produce quicklime, which was treated with water to release heat, forming slaked lime. The powder was then suspended in water and mixed with selected earthen grits like sand, marble powder, and crushed terracotta (Vitr. De Arch. 7.6.1). Finally, exposure to air would re-petrify the amalgam into a rock-hard calcium carbonate widely employed to protect and decorate buildings (Ling 1999, 210; Martin 1982, 248; Frizot 1977, 5) The sequence thus combined elements through complex chemical and manual procedures to produce one of the most ubiquitous, multipurpose, and seemingly simple surfaces to “finish” construction projects. I explore the multifaceted matter and function of plaster to ask: was ancient plaster a material or medium; technique or finished product? How might plaster’s composition relate to its (in)visibility to ancient authors and contemporary scholars alike? And how can close examinations of this ancient composite through ancient texts and material culture answer media-theoretical calls to “make environments visible” (Peters 2015, 38)?
I begin by exploring the terminology employed by ancient authors to refer to plaster. The (countless) variety of Roman plasters were mirrored by the wide semantic range of the terms opus tectorium, tectorium, opus albarium, or simply albarium in Latin, or koniama in Greek. This language could refer to both the material substrate and techniques of applying decorative architectural plaster, henceforth stucco (Martin 1982, 247). Moreover, early modern and modern usages of the terms “plaster” and “stucco” follow the ambiguity of their ancient counterparts (Gapper and Orton 2011). I argue this terminological intermediacy relates to a long tradition of artisans shaping and defining the boundaries of stucco through practice. I demonstrate how fluid definitions of stucco reside in expertise – namely, within the embodied knowledge of craftspeople who would mix appropriate elemental recipes together.
To do so, I turn to the material record and explore the tension between the broad terms used for describing stucco and its specific applications in Roman architecture. In the late Republican period, plastering shifted from a generalist to an increasingly specialist surfacing technique in two important designs – the “faux” ashlar walls of the “Masonry Style” and compartmentalized ceiling treatments in Rome and the Bay of Naples (Leach 2004, 262–64; Mielsch 1975; Ling 1972). Drawing together semantic and material strands, my case studies examine how artisanal expertise intersected with the translation or remediation of materials such as wood and stone in the stuccoing of those designs (Bolter and Grusin 1999). Plaster’s mixed-media composition created a fluid and malleable medium through which carpentry and stone working techniques were transformed into surface decorations, mediating ancient craft ecologies. I conclude by suggesting that in addition to an omnipresent, general medium used to “finish” architecture, plaster functioned as both an interface and its own form of generative infrastructure in the Roman world, broadly construed.