What is Permeability?

Permeability, a technical term used in the textile industry, is the capacity of a fabric to permit the passage of air or water vapor through it. This attribute is highly valued in textiles designed for diverse applications, including sportswear, medical textiles, and rainwear.

The permeability of a fabric is determined by a range of factors that contribute to its structure and properties, including the fiber type, weave or knit pattern, yarn structure, and finishing treatments.

Generally, fabrics with a looser weave or knit structure, and those made from hydrophilic fibers such as cotton, tend to have higher permeability. Conversely, fabrics with a tighter weave or knit structure, and those made from hydrophobic fibers like polyester, tend to have lower permeability.

Apart from contributing to comfort and breathability, permeability also plays a crucial role in the functional properties of protective clothing, such as moisture management, breathability, and waterproofing. For example, rainwear must be highly waterproof while allowing sweat to evaporate. Similarly, medical textiles like wound dressings must allow air and moisture to pass through while preventing bacterial contamination.

Measuring permeability involves various techniques such as the water vapor transmission rate (WVTR) and air permeability test. These methods provide quantitative data on the amount of water vapor or air that can pass through a fabric within a specific time frame, enabling designers and manufacturers to select fabrics that meet specific performance requirements.