WATERPROOF BREATHABLE FABRICS

In bad weather, your outerwear must be wind- and waterproof because it is expected to provide protection against wind and precipitation. A waterproof material is expected to fully protect from rain, snow, and wind and entirely prevent the penetration and absorption of liquid water. Usually, waterproof textiles act as a barrier between your body and the humidity in the environment. Indeed, waterproof fabrics may give you excellent protection from the elements, however, they are not able to transport the perspiration through the clothing to the outside causing a person to get wet from inside the clothing.

One possible solution to this problem is given by the so-called waterproof breathable fabrics (WBFs). The technology for manufacturing waterproof breathable textiles has been constantly developing and improving since the introduction of Gore-Tex in the 1970s. It is also quite diverse with plenty of new fabrics introduced through a steady blend of innovation and evolution. Garments made of waterproof breathable textiles are used by sports and outdoor enthusiasts and professionals in any conditions. A waterproof and breathable fabric combines two distinct functions – waterproofness and breathability. It should basically provide protection from the rain, snow, wind, and cold but also maintain comfort just below the fabric layer allowing internal water vapor to escape.

Functional outerwear must be waterproof for the maintenance of user comfort. Garments made of waterproof breathable fabrics shield from rain, snow, wind, and cold but allow for water vapor to be transferred from the inner to the outer environment in order to keep you warm and dry.

Techniques

The most popular techniques are two. The first one is to use a DWR that decreases the pore diameters of the fabric. Another technique is to cover the surface with an extra layer of a nonporous or microporous material that can keep out even the smallest water droplets. There are various ways of applying hydrophobic finishes. It can be done by using spray, wax, and lick roller as well as by padding.

Why do waterproof breathable fabrics need DWR treatment?

DWR treatment is used on waterproof fabrics to make drops bead on the surface and easily drip off instead of spreading on the fabric and wetting it. This prevents rain and snow from saturating the garment’s exterior maintaining fabric’s breathability. On the other side, the micro­porous film provides a barrier between your body and water droplets to give you protection from precipitation.

The main principle of how waterproof breathable textiles function (regardless of the fabric construction) depends on the relative humidity levels: if it’s more humid inside the jacket than outside, moisture will want to move outward to establish equilibrium and the opposite – if it’s more humid in the ambient environment than inside the outerwear, moisture will want to move inward. Therefore, the exterior face fabric of the jacket is critical for the passage of moisture meaning that the DWR applied must keep the face fabric drier than the inner side to allow the escape of interior moisture.