How To Tell If Your Clothing Is Breathable?
Aug 13, 2025
Definition of Breathability
Breathability refers to the permeability of gases through polymer materials such as films, coatings, and fabrics.
Fabric breathability refers to the ability of air to pass through a fabric when there is a pressure difference between its two sides. Specifically, it measures the volume of air that flows through a unit area of the fabric per unit time under a specified pressure difference, commonly expressed in units of mm/s. A pressure difference is a necessary condition for air flow; only when a certain pressure difference is maintained on either side of the fabric can air flow through it. Breathability affects the comfort of clothing, such as insulation and warmth. It is also an important way for the human body to dissipate heat, moisture vapor, carbon dioxide, and other gases.
Factors Affecting Fabric Breathability
Fabric-related factors:
1. Fiber morphology and yarn structure. When the linear density of warp and weft yarns and the arrangement density of warp yarns are the same, fabrics made of profiled fibers outperform those made of circular cross-section fibers. Fabrics with thicker single fibers exhibit better breathability than those with thinner ones.
2. Fabric weave structure. Under the same arrangement density and tightness, the order of breathability from weakest to strongest is plain weave < twill weave < satin weave < porous weave.
3. Post-finishing treatments. Dyeing and finishing processes tighten the fabric structure, reducing breathability. Weight reduction treatments thin the fibers and increase the gaps between fibers and yarns, thereby enhancing breathability.
Environmental factors:
1. At a constant temperature, the breathability of fabric decreases as the relative humidity of the air increases. When the fabric absorbs moisture, the fibers swell, and the pores contract, reducing the internal gaps and blocking the fabric's pores, leading to decreased breathability.
2. At a constant relative humidity, the breathability of fabric increases as the environmental temperature rises. The intensified thermal motion of gas molecules enhances their diffusion capacity.
3. When temperature and relative humidity remain unchanged, changes in the air pressure (P) on either side of the fabric will affect the measured flow rate, and this effect is nonlinear.
