What term describes the ability of a mold to allow gases to escape during casting?

The term that describes the ability of a mold to allow gases to escape during the casting process is permeability. Permeability refers to the capacity of a material, in this case, the mold, to transmit fluids or gases through its structure. This property is critical in metal casting, as gases formed during the melting and pouring of metal must escape to prevent defects and ensure a clean casting.

When molds have adequate permeability, they can effectively allow these gases to vent during the casting operation, reducing the risk of issues such as porosity or surface imperfections in the final product. This quality is necessary to achieve better quality in the casting process, as trapped gases can lead to voids and weaken the structure.

While strength, thermal stability, and collapsibility are important characteristics in different contexts of material performance or behavior, they do not specifically address the mold's ability to permit gas passage during casting. Therefore, understanding permeability is crucial for effective mold design and ensuring successful casting outcomes.