How do jackets achieve both waterproofness and breathability?

In outdoor sports, as a high-performance protective equipment, the jacket is favored by mountaineering, hiking, skiing and other enthusiasts because of its waterproof and breathable properties.

The uniqueness of a jacket is that it can effectively block the intrusion of rain in bad weather, while allowing sweat to be quickly discharged, keeping the wearer dry and comfortable. So, how does a jacket achieve these two seemingly contradictory functions of being waterproof and breathable?

The waterproof principle of jackets

The waterproof performance of a jacket is one of its core functions, and this performance mainly depends on the special structure and coating of its fabric. The fabric of a jacket usually adopts a multi-layer structure design, including the outer fabric, waterproof and breathable membrane, and lining . In this multi-layer structure, the waterproof and breathable membrane plays a vital role.

Multi-layer structure of waterproof and breathable fabric

This waterproof and breathable membrane is a high-tech film with a fine microporous structure, with a diameter of approximately 0.1 to 0.2 microns. The size of these micropores is carefully designed to be smaller than the size of liquid water droplets, so it can effectively prevent water penetration. At the same time, because the volume of water vapor molecules is much smaller than that of liquid water, they can pass through these micropores freely, thus achieving breathability. This design cleverly balances the needs of waterproofing and breathability.

Common waterproof and breathable membrane materials on the market include polyurethane (PU) membrane, polytetrafluoroethylene (PTFE) membrane, etc. It is particularly worth mentioning that Gore-Tex membrane, as a PTFE membrane, is widely used in the manufacture of high-end jackets due to its excellent waterproofness and breathability.

In addition to the waterproof and breathable membrane, the outer fabric of the jacket is also treated with a durable waterproof coating (DWR). This coating can make water droplets form ball shapes when they come into contact with the fabric, accelerating the sliding of water droplets, thereby reducing the penetration of water into the fabric. The DWR coating not only enhances the waterproof performance of the jacket, but also maintains the breathability of the fabric to a certain extent.

However, DWR coatings do wear out over time and use, so regular care and reapplication are necessary to ensure your jacket remains optimally waterproof. Proper care will not only extend the life of your jacket, but also ensure its reliability in a variety of adverse weather conditions.

The ventilation mechanism of the jacket

Breathability is another key feature in the design of a jacket, especially when doing high-intensity exercise. During intense exercise, the human body sweats a lot. If the sweat cannot be discharged quickly, the inside of the clothing will become damp and hot, which will not only reduce the wearer's comfort, but may also affect athletic performance.

The waterproof membrane of the jacket adopts a unique microporous structure. The diameter of these micropores is carefully designed to ensure that they are smaller than the size of water droplets, thereby effectively preventing water penetration. At the same time, the size of these micropores is large enough to allow water vapor molecules (whose diameter is much smaller than that of water droplets) to pass freely.

This design uses the characteristics of water vapor molecules escaping through micropores under the action of body temperature and heat generated by exercise to achieve excellent breathability. In this way, even after intense activities, the jacket can keep the inner layer dry and effectively avoid the discomfort caused by sweat retention.

To further improve breathability, jackets are usually equipped with a specially designed moisture-wicking lining . This lining uses advanced materials that can quickly absorb sweat from the skin surface and spread the sweat over a larger surface area through its special structure, thereby accelerating the evaporation of sweat. This ingenious design not only improves the breathability of the jacket, but also brings lasting comfort to the wearer after strenuous exercise.

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How to choose a suitable jacket?

After deeply understanding the waterproof and breathable mechanism of the jacket, we can make wise purchasing decisions based on our specific needs and activity environment. Here are some practical suggestions:

1

Waterproof grade selection

The waterproof performance of a jacket is usually measured by the "water column height" , which represents the height of water pressure that the fabric can withstand. The higher the water column height, the more waterproof the jacket is. For daily outdoor activities, such as urban hiking or occasional light rain, a jacket with a water column height of 5000 mm is usually sufficient.

However, if you plan to engage in activities in extreme environments, such as alpine expeditions or prolonged heavy rain, it is recommended to choose a jacket with a water column height of more than 20,000 mm to ensure adequate protection even in adverse weather conditions.

2

Breathability considerations

Breathability is an important indicator of whether a jacket can effectively expel moisture from the body. It is usually measured by "vapor transmission rate (MVTR)" or "breathability index". The higher the value, the better the breathability . If you plan to participate in high-intensity outdoor sports, such as mountaineering or trail running, it is very important to choose a jacket with high breathability to help regulate body temperature and reduce sweat accumulation.

On the contrary, in some more static activities, such as bird watching or camping, the requirements for breathability are relatively low, and you can choose a jacket with moderate breathability.

3

Suitable fabrics

The choice of fabric is crucial to the performance of your jacket. Different fabrics have different characteristics. For example, some fabrics are known for their excellent waterproof and breathable properties, which are very suitable for various extreme outdoor activities. Other fabrics are ideal for activities that require extra protection, such as rock climbing or skiing, because of their rugged and abrasion-resistant properties.

In addition, there are some lightweight fabrics on the market that are lighter in weight while maintaining a certain degree of waterproofness and breathability, making them suitable for short-distance hiking or urban commuting.

Planning and production

Source丨Popular Science of Physical Science (ID: lxcp_cstam)

Editor: Zhong Yanping

Proofread by Xu Lailinlin

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