What is the recommended cooling rate after reaching the final oven firing temperature?

The recommended cooling rate after reaching the final oven firing temperature is critical to ensure the integrity and durability of the refractory materials. A cooling rate of 500°F per hour strikes a balance between preventing thermal shock and allowing the material to stabilize as it transitions from high temperatures. Rapid cooling can lead to cracking or spalling, as the refractory can become too rigid before it has had time to uniformly lower its temperature.

Choosing a cooling rate that is too high increases the risk of creating stresses within the refractory that can lead to failure. Therefore, 500°F per hour is both effective in allowing the heat within the material to dissipate adequately while maintaining structural integrity, making it the optimal choice for this process in refractory applications.