Due to the extremely low porosity (less than 1%) of ADVANCER® kiln shelves, it takes prolonged exposure to a direct and continuous moisture source such as rain, standing water from a floor or condensation to penetrate the shelf. Water is slow to get in, and once in it is slow to get out. Therefore a temperature controlled dry out schedule must be observed prior to taking the shelves to normal firing temperatures. Slow bisque firing is not adequate to insure complete moisture removal! If you know or suspect that your shelves have water in them, you must follow the dry-out schedule outlined in the Saint-Gobain Technical Bulletin Warning “Storing and Drying Requirements for ADVANCER® Refractory Components.” If you are uncertain about moisture exposure problems with your shelves, please don’t hesitate to contact us!