Based on the need to develop a method to reliably and objectively document and discriminate the use-wear on archaeological stone tools, Stemp et al. (2009) tested whether the surface roughness measured on experimentally worn stone tools used on different contact materials could be discriminated. Results of these initial experiments indicated that discrimination was possible and also determined the scales over which this discrimination occurred. In this article, we report the results of additional experiments using the same method on a second set of tools to test its reliability and reproducibility. In these experiments, four flint flakes were intensively used for 20 min on either conch shell or dry deer antler. The surface roughness or texture of the stone tools was measured by generating 2D profiles using a UBM laser profilometer. Relative lengths (RLs) calculated from the profiles were used directly as characterization parameters and subsequently compared statistically at each scale using the F-test to establish a level of confidence for the differentiation at each scale represented in the measured profiles. The mean square ratios of measurement data were used to determine whether the variation in roughness was statistically significant and to what level of confidence. The scales at which there was a high level of confidence were the ones at which the tools were differentiable. The results of these experiments confirm our previous findings that RLs, over certain scale ranges, can discriminate the stone tool surface wear profiles produced by the different contact materials.

Although considerable progress has been made by archaeologists and materials scientists toward the development of a method to quantitatively document use-wear on stone tool surfaces, experimentation and refinement of methods continue. The experimental program tests root mean square roughness (rms or Rq) of measured profiles. for their ability to quantitatively discriminate the surface textures, or roughness, of experimental stone tools used on five contact materials (shell wood, dry hide, dry antler, and soaked antler). It employs a method for evaluating texture characterization parameters based on their ability to discriminate wear, and to determine a level of confidence for the discrimination, using the F-test. The results of this experiment demonstrate that Rq is not consistently reliable in discriminating measured profiles based on the wear caused by different contact materials on the stone tools.