Chapter 3
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The First Artificial Material: Ceramics from Prehistory to the Fall of Rome Nicholas Zumbulyadis* Independent Scholar, 2 Seneca Parkway, Rochester, New York 14613, United States *E-mail:
[email protected] The firing of clay is among the first chemical reactions humans intentionally used to create a new material. The earliest ceramic objects, ceremonial cult figurines from Dolni Vestonice (Czech Republic) have been dated to 28,000 B.P. The earliest utilitarian pottery are vessels from the Xianrendong cave (China), determined to be 20,000-19,000 old. The earliest ceramics from the Americas have been dated to 7,500-7,000 years ago. The archaeological record suggests that pottery was independently invented at multiple locations already by hunter-gatherers. Innovations in materials pro-cessing led to increasingly refined objects. These innovations include concepts such as using fillers to improve mechanical properties, control of reaction kinetics by particle size, carefully timed protocols for redox processes, and melting point depression by the addition of fluxes. The development of glazes, polychromy, and sophisticated kilns capable of higher temperatures and controlled kiln atmospheres will be discussed, as will the earliest chemical texts on ceramics.
© 2015 American Chemical Society In Chemical Technology in Antiquity; Rasmussen, Seth C.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.
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Introduction Ceramics today represent a very important class of artificial materials that are indispensable in meeting the diverse needs of a technologically complex society. Contemporary advanced applications range from biocompatible implants, to high temperature superconductors currently tested for the construction of powerful magnets, to heat and radiation resistant materials able to withstand the rigors of prolonged space travel and survive atmospheric reentry. In view of the chemical complexity of modern ceramics it is often easy to forget that ceramics can be thought of as the earliest artificial material used by humans since prehistoric times to make objects that met their practical, emotional, or transcendental needs. The history of ceramics is a vast and multifaceted subject. Archaeological and historic ceramic collections trace the evolution of human thought, reflecting our inventiveness, our aesthetic sensibilities and even our changing thoughts about Man’s place in the Universe. Trying to do justice to this vast topic in a short symposium chapter would be a fool’s errand. I have decided therefore to restrict myself to the vantage point of the chemistry historian, leaving out topics that might be of interest to the cultural anthropologist or art historian. For our purposes, the history of chemistry, broadly defined, traces the emergence of new materials and processes, and the evolution of concepts about the material world. And this is the vantage point I will primarily adopt in conjunction with the history of ceramics. Even so, I had to restrict myself to a few selected vignettes rather than attempt an exhaustive coverage of the topic. When reconstructing the development of chemical technology in prehistoric times, the chemistry historian has by definition no written records to go by and must rely on supporting evidence from archaeological chemistry. Even in historical times the records may have survived only partially if at all and may be hard to interpret. When researching more recent topics from within the period of recorded history, information can also flow the other way. The chemical historian can provide the archaeologist or art historian additional context for the interpretation of field observations or archaeometric laboratory data (1–3). In this chapter prehistoric dates determined by radiocarbon methods are given in BP (calibrated years before the present). For more precise dates during historical times the now standard convention BCE/CE has been adopted. Because of space limitations I have omitted the section on clay geochemistry included in my oral presentation. For the interested reader that might benefit from a very cursory introduction to this bewildering subject, the geochemistry portion of my Symposium talk is however posted online and and is available at ACS Presentations on Demand.
Paleolithic Ceramics and the Material Culture of Hunter-Gatherer Communities The dehydration and irreversible thermal dehydroxylation of clay are among the first chemical reactions humans intentionally used to create a new material. Our earliest evidence comes from artifacts discovered in Central Europe dating to 28,000-25,000 BP (Figure 1). The figure on the left is the very familiar Venus 72 In Chemical Technology in Antiquity; Rasmussen, Seth C.; ACS Symposium Series; American Chemical Society: Washington, DC, 2015.
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of Willendorf, a carved limestone figure. The ceramic figure on the right, the Venus of Dolní Věstonice from the Czech Republic resembles closely the Venus of Willendorf. The two are of similar age and signal what has been called the transition from a lithic tradition to a ceramic tradition.
Figure 1. (Left) Venus of Willendorf, discovered 1908 near Willendorf, Austria. Carved from oolithic limestone, dated to c. 28,000– 25,000 BP, H. 111 mm (4.4 in). Photography by Don Hitchcock, Wikimedia (Right) Venus of Dolní Věstonice, discovered 1925 south of Brno, Czech Republic. Fired loessic clay, dated to 29,000-25,000 BP, 111 mm by 43 mm (4.4 in by 1.7 in). Photography by Petr Novák, Wikipedia. The Dolní Věstonice site has yielded over 5000 ceramic artifacts made of local Pleistocene loess soil kneaded and shaped as moist paste, and then fired in walled structures serving as hearths or early kilns (4). The firing temperature was estimated to be 500-800 °C, in a reducing, carbon-monoxide-rich atmosphere judging by the grayish-black color of the artifacts. Impurity-initiated sintering allowed the consolidation of the clay into a ceramic object. Mostly animal and a few intact human figures but no utilitarian ceramics were recovered at this site. Table 1 gives a thumbnail sketch of ceramics from Paleolithic Europe and related sites in Northern Africa. We see that all of them are non-utilitarian artistic objects, fired at low temperatures (
