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Breathable Waterproof Fabric

Breathable Waterproof Fabric


Clothing made of waterproof breathable materials is intended to protect the wearer from the wind, rain, and loss of body heat. Since ancient times, people have worn clothing to shield themselves from the elements. The term "breathable" suggests that the fabric is actively ventilated. That is not the situation. Water vapour can diffuse passively through breathable materials, but liquid water cannot penetrate them. The skin's ability to produce water vapour is crucial for regulating body temperature. The typical body temperature is 37C and depending on the situation. The skin temperature ranges from 33 to 35C. Death occurs if the core temperature exceeds crucial thresholds between 24 and 45 degrees Celsius. The smaller boundaries of Unfavorable side effects like dizziness and convulsions are possible at 34 C and 42 C.

This could have disastrous effects if the patient is involved in a risky hobby or line of work. The body produces invisible perspiration as a component of its cooling mechanism during exercise. The relative humidity of the microclimate inside the clothes increases due to an increase in the thermal conductivity of the insulating air, making the clothing uncomfortable if the water vapour cannot escape to the surrounding atmosphere. If the body loses heat more quickly than it can produce, such as when physical activity has ceased.

Core temperature

If the core temperature has dropped, hypothermia may occur in extreme circumstances. When liquid sweat (sensible perspiration), which cannot evaporate, is created, the body is prevented from cooling as quickly as heat is generated. For instance, when exercising, hyperthermia can develop as the body's core temperature rises. Clothing must allow the passage of water vapour from perspiration at rates consistent with the activity conditions if the body is to maintain the physiologically appropriate temperature.

This property of a fabric is known as breathability. Water vapour permeability is a more technical name for this characteristic. Waterproof breathable fabrics allow water vapour to pass from within the clothes to the outside atmosphere while preventing liquid water from the outside from getting inside the garment.

Various waterproof and breathable fabric types

Several techniques can be employed to create materials that are waterproof and breathable. These fall into three categories:

  • Fabrics that are tightly knit.
  • Membranes coatings.
  • Densely woven materials.

The 1940s saw the development of Ventile, arguably the first genuinely successful waterproof and breathable fabric.

Ventile cloth was meticulously created to be efficient

The finest varieties of long-staple cotton are chosen with very little space between the fibres. The cotton is turned into combed yarn and plied after that. This increases uniformity, guarantees that the fibres are as parallel to the yarn axis as possible, and eliminates any large pores through which water may seep. The thread uses an Oxford weave, a plain weave in which the warp is formed by two threads working together. This ensures that the weft has the least amount of crimp and that the fibres are again as parallel to the fabric's surface as feasible.

The military variants use thread densities as high as 98 per cm. When the fabric surface is wetted by water, the cotton fibres swell transversely, reducing the pores' size and necessitating very high pressure to cause penetration. The fabric is thus rendered waterproof without needing any water-repellent finishing treatment. The waterproof characteristics of fabric used for various purposes need a water-repellent coating. Densely woven fabrics can also be produced using synthetic microfilament yarns.


The individual filaments can create fibres with microscopic pores because their diameter is less than 10 micrometres. Polyester or polyamide is typically used to make microfilaments. The latter is especially helpful because it naturally repels water—the ocean, Although microfilament textiles offer a soft handle. Many are windproof but not waterproof, as the synthetic filaments do not swell when wet. The fabric's penetration resistance is improved by applying a silicone or fluorocarbon finish. Compared to ordinary fabrics, the combination of fragile breathable fibres, filaments, and dense structure produces microscopic pores.

A waterproof cloth often has pores 10 micrometres in size instead of 60 micrometres for regular fabrics. When dry, the pore size of ventile fabric is approximately 10 micrometres; when wet, it is 3–4 micrometers2. According to claims, microfilament fabric can have up to 7000 strands per centimetre. There are roughly 6000 fibres per centimetre in the Ventile fabric used by the military.


Membranes are thin films formed of polymeric material designed to allow the passage of water vapour while having a very high resistance to the entrance of liquid water. A normal membrane is only 10 micrometres thick; therefore, it is laminated to a standard textile fabric to give it the required mechanical strength. They come in two varieties: hydrophilic and microporous.

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