Description General description Chemical porcelain has an average coefficient of expansion from 20°C to 200°C is 3.56 x 10-6, gradually increasing to 4.69 x 10-6 at 1000°C. To prevent thermal stress cracks on porcelain ware it is strongly recommended a heating/cooling rate not to exceed 200°C/hour. The desiccator plate has Small perforations throughout the plate, and one large hole in center. The plate is glazed on one side and is without feet. Refractory Qualities Fusion point: 1670°C Softening point: 1400°C Limit of use, unglazed: 1400°C Limit of use, glazed: 1150°C Limit of use, evacuated: 1300°C