Sweat without leaving any sweat? Why this magic tool can help you become the "most handsome guy" in the gym

During the sweltering dog days of summer, everyone must have experienced what it means to “go out for two minutes and sweat for two hours.”

In such weather, being a "sportsman" is like going through torture. The clothes are always wet, and when the wind blows, it is so "cool". However, as the saying goes, "Life is endless, sports are endless", hesitating for a second and not exercising is a disrespect for life.

So, how can you sweat and stay dry at the same time? Let's take a closer look at the sports magic tool - quick-drying clothes, and see how it can achieve "sweating without leaving sweat".

01

People sweat all the time?

The loss of water from the human skin surface can be divided into insensible sweating (non-visible sweat) and sensible sweating (visible sweat). Non-visible sweat refers to the water that evaporates from the human skin surface every moment, mainly in the form of gas; visible sweat refers to the sweat secreted by the human sweat glands when the human body is engaged in strenuous exercise or in a high temperature environment, mainly in the form of liquid. When the human body wears clothes, sweat vapor may exist at the same time as sweat, and sweat vapor may also diffuse in the fabric or condense into liquid water and be transmitted to the external environment [1].

Image source: sohu.com

Natural fibers, such as cotton fabrics, are the first choice when people buy clothes on a daily basis because they have good moisture absorption and are comfortable to wear. However, when the human body exudes a large amount of sweat, the cotton fibers will expand rapidly after absorbing moisture, thereby blocking the gaps between the yarns, replacing the static air that originally existed in the fabric, affecting the loss of moisture in the fabric, and thus causing a feeling of coldness and dampness to the human body[2]. Ordinary synthetic fibers, such as polyester, have a fast sweat absorption rate, but because the fibers themselves do not absorb water, their moisture absorption is very poor, which easily causes a feeling of stuffiness.

Image source: sohu.com

It can be seen that when people sweat a lot, ordinary clothes cannot absorb and discharge sweat in time, which brings many troubles to sports enthusiasts and sweaty people.

The emergence of quick-drying clothes has cleverly resolved these problems. It can absorb moisture and dry quickly at the same time. It has gradually entered the public's field of vision and become a new favorite in summer. So, what kind of clothes can be called quick-drying clothes, and how do quick-drying clothes absorb moisture and dry quickly?

Image source: a brand's official website

02

How do quick-drying clothes absorb moisture and dry quickly?

As the name suggests, quick-drying clothes are clothes that dry quickly. Quick-drying clothes are mainly made of chemical fibers, and some quick-drying clothes also contain cotton fibers. Unlike cotton fabrics, quick-drying clothes do not absorb sweat directly, but act as a "carrier" for sweat, allowing sweat to be quickly transferred to the surface of the clothes through the steps of moisture absorption, moisture conduction, and drying between the skin, fabric, and the outside world. The sweat is evaporated through air circulation, thereby achieving the purpose of moisture absorption and quick drying. Generally, quick-drying clothes dry 50% faster than cotton fabrics[3].

Moisture absorption and quick drying process Source: Zhihu

Seeing this, you may wonder, they are all fibers, why are quick-drying clothes so special? This is actually related to the fabric weaving structure, fiber cross-sectional shape and manufacturing process of quick-drying clothes.

(1) Fabric weaving structure design

Utilize the difference in water absorption between the inner and outer layers of fabric: for example, make the mesh on the inside of the garment larger and the mesh on the outside smaller, thereby creating a pressure difference for water movement. Utilize the "differential capillary effect" to continuously drain sweat from the inside of the garment to the outside and diffuse it quickly, achieving rapid evaporation [4].

Image source: sina.com

Image source: Reference [4]

It uses a double-layer fabric structure: the inner layer is made of hydrophobic and moisture-conductive polyester, which quickly transfers sweat from the skin to the outside so that we can always stay dry; the outer layer is made of hydrophilic yarn, which speeds up the transfer and evaporation of sweat, making the entire garment breathable[5].

Image source: Reference [5]

These two processes are used in relatively expensive one-way moisture-conducting fabrics, so that sweat or moisture can be quickly transferred from the inner layer of the fabric to the outer layer of the fabric and evaporate quickly, while sweat or moisture cannot seep back into the inner layer of the fabric, thus achieving the one-way moisture-conducting function.

Drop water onto the outer layer of clothing, spread it quickly, and keep the inner layer dry

Drop water into the inner layer of clothing and it quickly spreads to the outer layer, while the inner layer remains dry. Image source: fabricschina.com

(2) Use of differentiated fibers with special cross-sections

Conventional circular cross-section fibers have a smooth surface, poor adhesion, and do not absorb water, while fibers with special-shaped cross-sections have obvious grooves on their surfaces, like ditches, which use the "capillary effect" to quickly conduct sweat from the fiber pores and the fiber surface to the outer layer of the fabric for discharge.

Ordinary fibers and special-shaped cross-section fibers

Image source: Dingxiang Life Research Institute

At present, the well-known quick-drying clothing fabrics commonly seen on the market, such as Cool Max fabric, are based on this moisture absorption and quick-drying principle. They have super volatility and water absorption, which are 2 to 3 times stronger than ordinary cotton cloth, thus effectively ensuring the comfort and dryness of the wearer.

Image source: a brand's official website

(3) Finishing process

This process uses ordinary polyester and nylon as the main components, and relies on the dyeing and finishing process to soak and dry the fabric, and high-temperature shaping to attach the moisture-absorbing and perspiration-releasing agent to the fabric fibers, thereby achieving the moisture-absorbing and perspiration-releasing function. However, this kind of fabric is generally not washable. After multiple washings, the performance will be significantly reduced, and it will be almost the same as ordinary clothes[6].

03

How to choose the quick-drying clothes you like?

Nowadays, whether on shopping platforms or in shopping malls, there are a dazzling array of quick-drying clothes of different styles and prices. So how do you choose the quick-drying clothes you like?

(1) Check the fabric type

There are two main types of clothing fabrics with moisture absorption and quick-drying effects: one type is fabrics made of fibers with moisture absorption and quick-drying functions, which are called functional fiber fabrics; the other type is fabrics that have been post-finished to achieve moisture absorption and quick-drying effects, which are called functional finishing fabrics. The former type of fabrics has a more lasting moisture absorption and quick-drying effect, while the latter type of fabrics may lose their quick-drying effect as the number of washes increases. Generally speaking, the price of functional fiber fabrics is higher than that of functional finishing fabrics[7].

(2) Pay attention to functional labels and implementation standards, and do not blindly believe in propaganda

When purchasing quick-drying clothes, you need to check whether the tag or instructions indicate that it has special functions. Do not blindly believe in the promotion. If the quick-drying function is not marked, be cautious when purchasing. Look for products marked with the standard "GB/T 21655.1 (2)".

Image source: a brand's official website

(3) When purchasing quick-drying clothing, do not ignore its breathability

Quick-drying clothing with good air permeability is generally not heavy and feels cool when worn. We should be especially careful when purchasing water-repellent quick-drying clothing for outdoor wear. Water-repellent additives may be added during the finishing process, affecting its moisture absorption performance, or it may simply be a layer of waterproof coating added to the outside of ordinary quick-drying fabrics. It looks no different from ordinary quick-drying products and does not change the appearance and feel of the product, but this type of coated product has poor air permeability, so be careful when purchasing it[8].

Finally, I wish you can choose your favorite quick-drying clothes and spend a cool summer!

References

[1] Zhang Jingwei. Testing and evaluation of moisture absorption and quick-drying properties of special-shaped cross-section fibers and their fabrics[D]. Donghua University, 2013.

[2] Tang Hong, Jian Jie, Xiao Meng. Breathable fabrics: the development of moisture-absorbing and quick-drying functional fabrics[J]. China Fashion, 2007(05): 132-135.

[3] 【Quick-drying clothes_Baidu Encyclopedia】https://mbd.baidu.com/ma/s/oGvaf85O

[4] [What is the principle of quick-drying clothes? How to choose professional ones? - Bilibili] https://b23.tv/sCKQ9TG

[5] Zhang Feifei, Wang Wanan, Jing Zhuoyuan, et al. Research status and progress of unidirectional moisture-conducting fabrics[J]. Wool Textile Science and Technology, 2022, 50(06): 108-115.

[6] https://ml.mbd.baidu.com/r/13DTkBjAGe4?f=cp&u=210ac94383a15318

[7] Are you wearing moisture-absorbing and quick-drying clothes correctly? [J]. Fujian Quality and Technical Supervision, 2015(11): 57.

[8] Liu Yongjie, Hu Haina, Guan Jie, et al. Analysis and suggestions on quality problems of quick-drying clothes[J]. China Fiber Inspection, 2022(09): 32-34.

Author: Shen Didi, Master’s student of Materials Science Department, Fudan University

Editor: rain

Acknowledgements: Sun Yafei, a chemical engineer and PhD student from the Department of Chemistry at Tsinghua University, provided scientific guidance for this article

Title image source: sina.com