Schematic illustration of the two sets for the cooling effect of cordierite. The blue sheets represent the metal sheets and the orange sheet represents the cordierite covered on the metal sheet. (a) Set A: Put the piece of copper sheet onto the hot plate and cover half of the copper sheet with cordierite. When the metal sheet reaches thermal equilibrium, measure the temperature of the cordierite and bare metal. (b) Set B: Put two pieces of metal sheets onto the hot plate and cover one piece of the metal sheet with cordierite. After reaching thermal equilibrium, two sheets were moved to the iron supports and cooled by air. The temperature of the two sheets and corresponding time were recorded then. The illustration in the upper right corner shows the difference between the infrared radiance of two different metal plates.