In the hot summer, sunscreen clothing has become a necessary sunscreen for many people ". However, recently, some netizens issued a "soul torture": why wear a sunscreen, or be tanned?

So, what is the principle of sun protection clothing? Why wear sunscreen clothing or will be tanned? This science and technology daily reporter interviewed the relevant experts.

"The main thing to prevent sunscreen is ultraviolet rays." Zhang Jing, an associate professor at the Beijing Institute of Clothing Technology, said in an interview with Science and Technology Daily that the ultraviolet rays that reach the earth mainly include long-wave ultraviolet rays (UVA) with a wavelength of 320 nanometers to 420 nanometers and medium-wave ultraviolet light (UVB) with a wavelength of 270 nanometers to 320 nanometers, of which UVA accounts for more than 90%, which is the "real killer".

Clothing plays an important role in preventing the human body from being damaged by ultraviolet rays. People's daily wear clothing usually has a certain anti-ultraviolet function, when ultraviolet radiation to the surface of the clothing, will occur reflection, scattering, absorption, through the phenomenon, so that the human skin by less damage.

However, the protective effect of daily clothing on ultraviolet rays is limited. When exposed to strong sunlight for a long time, we need clothing with higher ultraviolet protection.

"Sunscreen clothing is made of anti-ultraviolet textiles. It dissipates the ultraviolet rays irradiated on the clothing by reflecting, scattering, and absorbing, thereby reducing the damage to the human skin, so as to achieve the purpose of sun protection. 」 Zhang Jing said.

Ultraviolet protection factor (UPF) and UVA transmittance are the indexes to evaluate the sunscreen performance of fabrics. The higher the UPF value and the lower the UVA transmittance, the better the UV protection performance of the textile. According to China's relevant industry regulations, the UV protection coefficient of anti-ultraviolet textiles must be greater than 40, and the UVA transmittance must be less than 5%.

"Sunscreen clothing that does not meet the above standards does not provide good sun protection. 」 Zhang Jing said that in addition, sunscreen clothing that is old, frequently washed or often worn in a humid environment may cause its protective effect to be greatly reduced. If the sun protection clothing fabric appears obvious light transmission, or the fabric structure appears slack phenomenon, it should be considered to replace.

So, how do we choose sun protection clothing science?

"The sunscreen effect of sunscreen clothing is closely related to the type of fiber material, the tightness of the weaving structure, the thickness of the fabric, the depth of color and other factors." Zhang Jing further said that, for example, among natural fibers, cotton and silk have a general sunscreen effect, wool is slightly better, and flax is the best; among chemical fibers, polyester fibers, namely polyester, have the best sunscreen effect. In addition, the higher the density of the woven structure of the fabric, the thicker, the lower the penetration rate, the better the sunscreen effect.

According to relevant experts, the common sunscreen fabric on the market is polyester, followed by nylon, or a fabric made of polyester and nylon. When consumers buy, it is recommended to choose dark sunscreen clothing, such as black, navy blue, dark blue, dark purple, red, etc., among which red sunscreen clothing has the best sunscreen effect.

In addition, when cleaning sunscreen clothing, try to wash it gently with your hands to avoid rubbing the clothes hard, destroying the sunscreen effect of the fabric, or causing the fabric structure to relax.