Between grooves and pits: Trephic modifications resulting from air-scribe cleaning of archaeological bone

The taphonomic analysis of surface modifications on bones is crucial for reconstructing the past, but it can be influenced by various trephic processes, including cleaning interventions. Mechanical cleaning is one of the most common types, and automatic tools are often used for highly concreted materials. In this study, the modifications resulting from the cleaning of concreted archaeological bone material using an air scribe were characterized. First, an experiment was conducted in which the air scribe was applied directly to the bone surface at different angles, and the modifications were documented. As a result, three categories of modifications were identified: pits, fine grooves, and wide grooves. Subsequently, two sets of archaeological samples with concretions of different characteristics were cleaned, and the observed modifications were related to those obtained in the experimental phase. Variables influencing the appearance of these modifications were also analysed based on the site's characteristics and the concretion surrounding the bone. Once the modifications resulting from cleaning were characterized, they were compared to taphonomic surface modifications on the bone to determine if they could influence taphonomic studies, thereby avoiding potential confusion between them. This work allowed for the identification of the specific effects of this type of mechanical cleaning tool and the prevention of issues of equifinality in subsequent taphonomic studies.