A simple, robust test method was developed for measuring pyroplastic deformation of a whiteware body based upon the calculated stress on a body during firing. Stress is determined from sample geometry, size, and span. A pyroplastic index is generated based on sample stress and deformation, which successfully demonstrates the ability to characterise the deformation tendency. Two deformation events are apparent in deformation versus firing temperature data, both due to viscous flow. A significant portion of deformation occurs in a non-steady-state region of firing, far below the dwell temperature, proposed to be due to heterogeneties caused by microstructural evolution of the body. A secondary deformation event, proposed to be steady-state creep, occurs at the dwell temperature.
