A preliminary study of rotation velocity regulation in pottery wheel-throwing: Fieldwork with Indian potters using the low-inertia kick-wheel

• Gandon Enora
• Coyle Thelma
• Pous Frédéric
• Buloup Franck
• Bootsma Reinoud J.

• Pottery wheel-throwing
• Potter's wheel
• Rotation velocity
• Linear velocity
• Motor skill
• Expertise
• Field experiment
• Low-inertia kick-wheel

The present study examined rotation velocity regulation in pottery wheel-throwing. Long assumed to be a key parameter in the control of the centrifugal force, we interpret its role rather as a means to control the linear velocity at the point of hand-clay contact. To test this hypothesis, we set up a field experiment with Indian potters working with a low-inertia kickwheel. Six expert potters were asked to produce eight types of pots (four shapes × two masses), each type in five specimens (in total each potter threw 40 vessels). We measured the rotation velocity during the pre-forming and forming fashioning phases, as well as the maximal vessel radii at the end of both phases. Results demonstrated that potters reduced the rotation velocity from the pre-forming phase to the forming phase, but also for the large clay masses compared to the small clay masses, and-uniquely during the forming phase-for the shapes characterized by the largest diameter. Overall, the observed decreases in rotation velocity corresponded to increases in mean vessel diameter, suggesting that the potters were applying a limit on the linear velocity. Our results thus provide empirical evidence supporting the role of linear velocity as a key functional parameter in wheel-throwing. Directly relating to the potter-vessel interaction, it indicates both when and by how much the rotation velocity deceleration caused by the exertion of manual pressure forces should be compensated, as well as how to avoid the risk of velocity-induced collapse. While only preliminary, our results also suggest that large-sized ancient wheel-thrown vessels were most likely produced using low-velocity and high-inertia wheels. Future work, examining rotation velocity regulation over different types of wheels, is needed to allow definite conclusions to be drawn.