Micro-Computed Tomography with 3D Image Analysis to Reveal Firing Temperature Effects on Pore Systems in Archaeological and Ethnographic Ceramics

Abstract

Understanding the firing regimes of archaeological ceramics reveals clues about the history of technological developments, but current methods for determining firing history have limitations. We experimented with non-destructive micro-CT combined with 3D image analysis to collect data on 42 pore variables, hypothesizing that pore systems are affected by ceramic firing temperatures. Analysis of variance showed that 26 of the variables are significantly related to firing temperature. Total volume porosity (open and closed pores) goes down with increased firing temperature, as does the fraction of pores accessible to a surface. Maximum pore volume, maximum and standard deviation of pore surface area, and pore elongation measures all decrease with higher firing temperatures while shape factors indicating greater sphericity increase. Pore connectivity measures decrease with higher firing temperatures, and variation in pore and connection lengths increases. The highest fired ceramics have low connection tortuosity. Three-dimensional image analysis of micro-CT data can augment existing methods of archaeothermometry, and since many pore characteristics impact the functional properties of ceramics (density, durability, mechanical strength, thermal conductivity, permeability, and diffusion), firing temperature studies of pore systems can inform wider archaeological ceramics research.