Refractory products contained pore size and the percentage of total volume of products. Refractory products in the pore is divided into two categories: closed in products not connected with the outside world that keeps stomatal pore; linked with the outside world, is the fluid-filled open stomatal pore said. In the pore openings, runs through both sides of products, fluid can link up through the pores called stomata. Open pore size and the ratio of total volume of products known as the open porosity, Chang said apparent porosity, credited to P, frequently pore size and the ratio of total volume of products that implicit porosity.