Membranes

Gore-Tex membrane seen at the microscope

The impermeability of sportswear is obtained, in most cases, thanks to the use of waterproof membranes that are attached onto the inner surface of the main fabric of a garment through a delicate process of gluing called lamination.

Membranes are in many cases obtained from thermal expansion of polytetrafluoroethylene (PTFE, commercially known as Teflon) or other plastic polymers. Through this process a membrane is obtained that has a peculiar structure dotted with millions of micro pores. The size of these pores is small enough to prevent the passage of water droplets, but large enough to allows the passage of water vapor molecules. Other membranes also exist that are made of some kind of filamentary structure. The filamentsform a net with apertures of the right size to stop water droplets, but to let water vapor molecules pass, in much the same way as the micro porous membranes work,

The most famous waterproof membrane is undoubtedly the Gore-Tex, but there are dozens of equally valid, but not successfully advertised membranes, for example eVent, Sympatex, Dermizax, just to name a few.

In sportswear the use of these membranes matched to specific fabrics allows to have totally waterproof garments that do not prevent, during physical activity, the normal exchange of vapor between the body and the external environment. 

At least that's the theory...

Combination with fabrics


While the membrane provides the water resistance of a garment, the combination with different fabrics give the laminates different characteristics, most suitable for a purpose rather than another.
Waterproof membranes are very delicate and they need support and protection. Also the wear and dirt tend to inhibit waterproofness and breathability of membranes. Therefore, membrane surfaces must be somehow protected. Usually, a mesh lining is used on the inside, while on the outside a tougher fabric protects also from abrasion. The thickness, density and weight of the outer and inner fabrics are important since they may affect the behavior of the membrane differently.


2-Layer construction

In 2-layer constructions the lining is detached from the main layer, which is composed by the outer fabric laminated to the membrane.









3-Layer construction

In 3-layer constructions the lining, the membrane, and the outer layer are laminated together to form a unique material, which is generally more compact and more durable. At a tactile examination it is not possible to distinguish the individual layers.

In some laminated 3-layer fabrics, the inner lining is made of a thin fleece. In this case the fabric is thicker and heavier, but it provides greater insulating power, more comfort and it has the advantage of replacing the intermediate insulating layer in the layered clothing system.





Ultra-thin 3-layer construction (or 2.5-layer)

Looking for a product that is lightweight and packs in a small volume some manufacturers have replaced the inner lining with a lighter coating substance to protect the membrane, usually oleophobic substances and carbon. Examining these extremely light material, we will notice that the inner surface has a "plastic" dark-gray/black look. In some cases "printed", embossed, or patterned designs are present directly on the membrane with the same mix of substances. Those are intended to protect the membrane and facilitate the sliding on the underlying garments.




Taping


The small holes left by the needle that sews the various parts of a garment are weak points through which water can penetrate. On a jacket, for example, where the stitches may be thousands, the need to seal these spots becomes essential. For this reason the seams of some laminates are sealed by glueing a sort of adhesive tape composed of the same laminated material of the garment. This guarantees the total waterproofness of a garment.







Suggested uses


In general, the 3-layer (or 2.5-layer) construction is used on the most technical garments intended for more "extreme" uses, where strength, versatility, low weight and top performances are essential.
The 2-layer construction instead, are designed to be used in a wide range of outdoor activities, from hiking to biking, from fishing to skiing/snowboarding. The comfort they offer in layered clothing system is superior to the other solution, because it has a less "cold" and "plastic" feeling compared to the 3-layer construction.