Porcelain Desiccator Plate, 230mm, Perforated, with Center Hole. Perforated porcelain desiccator plate with a large hole in the center for easy placement or removal from a glass desiccator. Plate is glazed on one side.Porcelain Labware has excellent resistance to all reagents except hydrofluoric acid, and is highly resistant to thermal shock while having a very low coefficient of expansion.The average coefficient of expansion from 20° to 200°C is 3.56 x 10-5 gradually increasing to 4.69 x 10-5 at 1000°C. To prevent thermal stress cracks on porcelain ware do not exceed a heating/cooling rate of 200°C per hour.To prolong the life of porcelain products:• Follow gradual heating/cooling rates• Use an oven or hot plate and an intermediate step when quicker heating/cooling rates are required• Avoid contact of heated ware with a cold surface• Carefully inspect labware prior to each use and do not use any product that appears defective.