What are the two primary mechanisms through which moisture moves through hygroscopic materials?

The correct identification of the two primary mechanisms through which moisture moves through hygroscopic materials is capillary action and vapor diffusion.

Hygroscopic materials, such as wood, paper, and certain textiles, have the ability to absorb moisture from the environment. Capillary action refers to the process by which water moves through the small spaces within these materials, often against the force of gravity. This occurs due to the intermolecular forces between the liquid and the surrounding solid material. As such, water can move upward or laterally in a material, which is especially relevant in situations where materials are saturated and need to be dried.

Vapor diffusion, on the other hand, describes how moisture in the form of water vapor moves from areas of higher concentration to areas of lower concentration. This process is driven by differences in vapor pressure and is an essential mechanism in the drying process, allowing moisture to escape from the surface of hygroscopic materials into the air.

Together, these two processes are crucial for understanding how moisture is managed in restoration and drying operations, as they directly impact the effectiveness of drying efforts and the overall integrity of the material being treated.