Surface Treatments and the Interpretation of Vessel Function from a Performance Perspective

Ceramic function can also be looked at from a performance perspective. A ceramic vessel can have certain performance characteristics that make it useful for some tasks but not others. For example, a potter might form a vessel with very thick walls to make that vessel strong or durable. Thick walls, then, would increase a vessel's strength performance. At the same time, a thick-walled vessel would be heavy, and therefore decrease its transportability. Archaeologists often isolate particular vessel attributes, such as wall thickness, to understand how that attribute affects the vessel's performance. By doing so, archaeologists get a better understanding of how that vessel was used. The performance of three kinds of surface treatments, corrugation, slipping, and painting, will be examined below.

1. Texturing

Corrugation is a form of surface texturing that occurs on prehistoric cooking pots from the American Southwest. For years, Southwestern archaeologists debated the function of corrugation. Initially, archaeologists suggested that corrugation was purely aesthetic and played no role in the mechanical performance of a vessel. Others argued that corrugations allowed for easy handling, especially if the vessel was hot. Later, corrugations were examined from a performance perspective, and archaeologists proposed that they, the corrugations, increased a vessel's heating effectiveness. Important experiments conducted by Young and Stone (1990), Schiffer et al. (1994), and Pierce (1996) eventually discredited this hypotheses. Experiments carried out by Christopher Pierce (Pierce 1994) offer a potential resolution for the corrugation dilemma. In comparing the use-life of corrugated versus non-corrugated vessels, he subjected both kinds of vessels to hundreds of hours of cooking experiments and found that the corrugated vessels lasted longer than the plain vessels. Corrugations, thus, enhance a vessel's cooking performance by increasing the length of time that it can be used.

Figure 2.2.10  Corrugated jar.

2. Slipping

The slipped surface of a vessel has many performance characteristics. First of all, a slip, which is a thin wash of clay applied to the surface of a vessel, creates a smooth, even surface on which a potter can paint designs. Secondly, a slip creates a nearly impermeable layer so that food or other residues do not soak into the clay body. This allows for easy cleaning. Finally, experiments conducted by Michael Schiffer (1990) show that slipping increases a vessel's heating effectiveness. He suggests that this is because the slipped, impermeable layer prevents the vessel contents from soaking into its walls. This way, energy is expended in boiling whatever is inside the pot rather than burning off the liquid within the pot's walls. Schiffer also found that other surface coatings on prehistoric pots such as resin and smudging act in the same manner.

Figure 2.2.11  Slipped bowl.

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