Evaluating the microscopic effect of brushing stone tools as a cleaning procedure

Cleaning stone tool surfaces is a common procedure in lithic studies. The first step widely applied at any archeological site (and/or at field laboratories) is the gross removal of sediment from the surfaces of artifacts. Lithic surface alterations due to mechanical action applied in wet or dry cleaning regimes have never been examined at a microscopic scale. This could have important implications in traceology, as any modern surface modifications inflicted on archeological artifacts might compromise their functional interpretations. The current trend toward quantification of use-wear traces makes the testing even more important, as even slight, apparently invisible surface alterations might be measured. In order to evaluate the impact of common cleaning procedures, we undertook a controlled experiment. The main aim of this experiment was to assess the effects that brushing actions applied for removing sediment particles have on flint and quartzite surfaces. All surfaces were analyzed with confocal microscopy before and after having been brushed to quantify possible changes in the micro-topography. Surface roughness parameters (ISO 25178-2 among others) were applied. Nine parameters changed significantly when mechanical actions were applied to lithic surfaces, meaning that some changes in the surface micro-topography were detected. Therefore, archeologists need to be cautious when applying prolonged mechanical actions for cleaning archeological stone tools.info:eu-repo/semantics/publishedVersio

The effect of numerical aperture on quantitative use-wear studies and its implication on reproducibility

Many archeologists are skeptical about the capabilities of use-wear analysis to infer on the function of archeological tools, mainly because the method is seen as subjective, not standardized and not reproducible. Quantitative methods in particular have been developed and applied to address these issues. However, the importance of equipment, acquisition and analysis settings remains underestimated. One of those settings, the numerical aperture of the objective, has the potential to be one of the major factors leading to reproducibility issues. Here, experimental flint and quartzite tools were imaged using laser-scanning confocal microscopy with two objectives having the same magnification but different numerical apertures. The results demonstrate that 3D surface texture ISO 25178 parameters differ significantly when the same surface is measured with objectives having different numerical apertures. It is, however, unknown whether this property would blur or mask information related to use of the tools. Other acquisition and analyses settings are also discussed. We argue that to move use-wear analysis toward standardization, repeatability and reproducibility, the first step is to report all acquisition and analysis settings. This will allow the reproduction of use-wear studies, as well as tracing the differences between studies to given settings.Agência financiadora Romisch-Germanisches Zentralmuseum -Leibniz Research Institute for Archaeology by German Federal and Rhineland Palatinate funding (Sondertatbestand "Spurenlabor")info:eu-repo/semantics/publishedVersio

Surface texture analysis in Toothfrax and MountainsMap® SSFA module: Different software packages, different results?

Pre-print: Calandra_etal_SSFA_PCIarchaeo_revised.pdf (figures incorporated, but additionally available as separate PDF files) Supplementary Material: Bayesian-models_PCIarchaeo_revised.pdf and Comparison-analyses_PCIarchaeo_revised.pdf See also related identifiers for the other supplementary materials. Revised version submitted to PCI Archaeology

Polish is quantitatively different on quartzite flakes used on different worked materials.

Metrology has been successfully used in the last decade to quantify use-wear on stone tools. Such techniques have been mostly applied to fine-grained rocks (chert), while studies on coarse-grained raw materials have been relatively infrequent. In this study, confocal microscopy was employed to investigate polished surfaces on a coarse-grained lithology, quartzite. Wear originating from contact with five different worked materials were classified in a data-driven approach using machine learning. Two different classifiers, a decision tree and a support-vector machine, were used to assign the different textures to a worked material based on a selected number of parameters (Mean density of furrows, Mean depth of furrows, Core material volume-Vmc). The method proved successful, presenting high scores for bone and hide (100%). The obtained classification rates are satisfactory for the other worked materials, with the only exception of cane, which shows overlaps with other materials. Although the results presented here are preliminary, they can be used to develop future studies on quartzite including enlarged sample sizes

Enhancing lithic analysis: Introducing 3D-EdgeAngle as a semi-automated 3D digital method to systematically quantify stone tool edge angle and design.

In stone tool studies, the analysis of different technological and typological features is known to provide distinct but interrelated information on the design and use of artefacts. The selection of these features can potentially influence the understanding and reconstruction of past human technological behaviour across time. One feature frequently part of a standard lithic analysis is the measurement of edge angles. The angle of an edge, unmodified or shaped by retouch and an integral part of the overall tool design, is certainly a parameter that influences the interpretation of an artefact. The acuteness of an edge angle is often linked to aspects such as cutting, carving, or scraping efficiency and durability and thus, tool performance. Knowing the actual edge angle of a stone tool can therefore have important implications for its interpretation. In the case of edge angle analyses, manual measuring techniques have been established for many years in lithic studies. Here, we introduce a new method for accurate and precise edge angle measurements based on 3D data (hereafter 3D-EdgeAngle). 3D-EdgeAngle consists of a script-based, semi-automated edge angle measuring method applicable to 3D models. Unlike other methods, 3D-EdgeAngle illustrates an objective way of measuring the edge angle at cross sections along the entire tool edge in defined steps and, moreover, allows measurements at different distances perpendicular to the edge by controlling three involved parameters. Thus, with this method, the edge angle can be measured at any point in a high resolution and scale of analysis. Compared to measurements taken manually, with this method random and systematic errors can be reduced significantly. Additionally, all data are reproducible and statistically evaluable. We introduce 3D-EdgeAngle as a standard method to calculate edge angles with a highly accurate and systematic approach. With this method, we aim to improve the process of studying lithics and thus to increase the understanding of past human tool design