Schematic diagram of the experimental setup. A rectangular tank of size 114 × 36 × 10 cm3 is filled with Shell Callista 158 wax which melts at about 72°C [20, 34]. The mechanical properties of micro-crystalline wax are brittle at room temperature and paste-like close to the melting point. No detailed mechanical measurements are performed. The tank is heated from below to (80.0 ± 0.05)°C and cooled from above by a constant flow of air at (12.0 ± 2.0)°C. Credit: Richard Katz/New Journal of Physics.