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The activity of wheel-throwing a ceramic vessel is governed by a number of physical forces. These are the rotational kinetic energy (expressed in terms of angular velocity and the moment of inertia) and manual pressures. Given the importance of the potter's wheel worldwide, and the frequently postulated socio-cultural meaning of wheel-throwing in particular, foundational research on the physics behind wheel-throwing has been under-represented, and there is a lack of understanding of the relationship between speed of wheel rotation, lifting speed and the orientation of clay pores or inclusions. The speed of rotation is highly relevant as different wheels can achieve different speeds. Thus, knowing the speed during manufacture may allow scholars to reconstruct the original device, manufacturing technique, and perhaps even the potter's level of skill. Two contrasting views can be found in the literature: a) there is a direct positive relationship between these variables, and that the angle of the inclusions/voids can therefore tell us about the wheel's speed at the time of making the pot and hence the device used; b) because pots are never thrown in one single motion, the angle of inclusions/voids is an averaging of all actions executed by the potter, and thus cannot provide meaningful inferences about speeds or device. Experiments with professional potters were devised to explore the relationship between these variables. They show that the interaction between the various physical forces, clay and potter is complex, leading to a large variance even within the work of a single potter, with finger pressure recognized as a major influencing variable. It is clear that angles of inclusions or voids cannot be used to project backwards to the wheel speed, lifting speed, skill level or device used.

International audience; At the crossroad of archaeology and experimental psychology, we addressed the issue of inter-individual variability in traditional ceramic shapes. The goal was to explore whether such variability could imply potter signatures. We setup a field experiment with five expert Nepalese potters, asking them to produce three shapes (replicated five times). The 2D profiles of the experimental productions were analyzed with a shape analysis method borrowed from biology. In a complementary experiment focusing on shape discrimination, the participants were asked to visually identify their own productions and those of their colleagues. Results indicated that the potters produced slightly but significantly different shapes. We assume that during apprenticeship individuals developed their own motor skills, which reflect upon the finished products. Interpreting shape variability in terms of individuals could provide supplementary information on the social organization of the production, either for modern or ancient periods. As for shape discrimination, our preliminary results indicated that a few potters visually distinguished individual signatures. Those craftsmen could play a key role in the selection and evolution of the traditional ceramic shapes.

International audience; This research has been conducted in the context of the ArtiMuse project that aims at the modeling and renewal of rare gestural knowledge and skills involved in the traditional craftsmanship and more precisely in the art of the wheel-throwing pottery. These knowledge and skills constitute the Intangible Cultural Heritage and refer to the fruit of diverse expertise founded and propagated over the centuries thanks to the ingeniousness of the gesture and the creativity of the human spirit. Nowadays, this expertise is very often threatened with disappearance because of the difficulty to resist to globalization and the fact that most of those "expertise holders" are not easily accessible due to geographical or other constraints. In this paper, a methodological framework for capturing and modeling gestural knowledge and skills in wheel-throwing pottery is proposed. It is based on capturing gestures using wireless inertial sensors and statistical modeling. In particular, we used a system that allows for online alignment of gestures using a modified Hidden Markov Model. This methodology is implemented into a Human-Computer Interface, which permits both the modeling and recognition of expert technical gestures. This system could be used to assist in the learning of these gestures by giving continuous feedback in real-time by measuring the difference between expert and learner gestures. The system has been tested and evaluated on different potters with a rare expertise, which is strongly related to their local identity.