Documenting Cordage Impressions on Archaeological Ceramics: A Methodological Comparison of Casting and Digital Representation

Abstract

The analysis of cordage and fabrics from the impressions and markings on pottery has traditionally been conducted by casting the pottery sherds with a plastic or liquid media to make a positive. This positive is then analyzed by measuring attributes under a low-power microscope with calipers. Original Sculpey® is one casting media that has been popular because of its price, accessibility, detail of cast, and permanency of the casts after curing. However, it has been found to impart an organic chemical signature on the sherds, which would bias residue analyses. Further, the plasticizer in Original Sculpey® can soften certain plastics, notably Paraloid B-72, which is often used on pottery as a consolidant. 3D scanning, then, theoretically can be used to create digital representations of the impressions and markings in pottery, while avoiding damage to the sherds and other conservation concerns. The NextEngine 3D laser scanner was tested in the analysis of seven sherds with varying qualities of impressions and markings. Results revealed that the method one uses depends not only on the quality desired and the conservation of the sherd, but also cost, time, and expertise available to the researcher. While the NextEngine itself may not be able to achieve the level of detail needed to match casting methods, the technology can be nonetheless useful for impressed sherd documentation in the near future.