Solar spectrum test system for sunscreen effect of sunscreen clothing

Solar spectrum test system for sunscreen effect of sunscreen clothing

Summer, Hangzhou, the temperature on the rub rubbing against the heat and go straight. At this time, the girls are worried again: how to bask in the dark? Many of the girls in addition to sunscreen, playing sunshade, but also buy sunscreen clothing. So, are these light and thin sunscreen suits really sunscreen?

No, the experiment for the proof, this issue of "Curiosity Laboratory" on the measured sun-proof clothing sunscreen effect.

Your tanning is UVA.

"Sunlight is divided into visible and invisible, visible light refers to the naked eye can see, such as the sun in the red, orange, yellow, green, blue, indigo, purple seven-color rainbow light; Invisible light refers to the naked eye, such as ultraviolet, infra-red. "said Ye Linhua, an associate professor at the Optics Institute of Zhejiang University.

In the sun, the greater the damage to the human body is ultraviolet rays, which are divided into shortwave (uhttp://www.aliyun.com/zixun/aggregation/309.html ">VC"), medium wave (UVB) and Long-wave (UVA) according to wavelength.

Short-wave ultraviolet rays are absorbed by the ozone layer, most of which are absorbed by the skin's epidermis and do not penetrate the skin, and long wavelength ultraviolet rays can penetrate the skin through glass and clouds, which is the culprit of tanning.

Therefore, sunscreen clothing to prevent sunscreen, not only to see the clothes on the sun blocking effect, but also to see the role of ultraviolet radiation barrier.

Ye Linhua, an associate professor, built a solar spectrum test system for the express time. The experimental principle is this

Optical fiber probes collect the intensity of the sunlight, and get the solar spectrum distribution curve by computer software. The stronger the light in a certain band, the higher its peak.

The object of the experiment was long wavelength ultraviolet rays, which were mainly distributed in the 360 nanometer solar spectral region.

Block the sunscreen on the optical fiber probe and measure the intensity of light transmitted to the probe after blocking the sunscreen suit.

Finally, the calculation of the shielding before and after the measured light intensity of the value, you can learn that the transmittance of the sun is the lower the rate of transmission, sunscreen clothing blocking the effect of UVA ultraviolet radiation is better.

More than 30,000 sunscreen clothes

Three randomly purchased without UV-proof coefficient

Taobao on the search for sunscreen clothing, jumped out of more than 30,000 items, priced from 5 yuan to thousands of dollars, the characteristics of these sunscreen clothing are mostly bright colors, light and thin.

We randomly bought 3 kinds of sunscreen suits.

The first: Price 22 yuan, orange cotton sunscreen clothing, at first glance and ordinary cardigan no difference, is particularly thin.

The second: The price is 78 yuan, yellow sunscreen clothing, looks like ultra-thin plastic raincoat. The owner said, "This is made of silk, is the unique fabric of sunscreen clothing." ”

The Third Kind: The price is 159 yuan, the white senior sunscreen clothing, the fabric is the chemical fiber, the workmanship is exquisite.

Careful examination, the three kinds of sunscreen clothing labels do not indicate the UV-proof coefficient, there is no sunscreen material description.

Three sunscreen suits are available

But they're not as good as plain cotton t-shirts.

Three pieces of sunscreen in a single layer case, the result is 78 yuan yellow "days of silk" sunscreen clothing of the spectral distribution curve is the most obvious, followed by the value of 22 yuan of orange cotton sunscreen clothing, and finally the value of 159 yuan of white chemical fiber sunscreen clothing.

Yellow "Day silk" sunscreen clothing and orange cotton sunscreen clothing long wave ultraviolet transmittance is 12%, and the white chemical fiber sunscreen clothing is up to 28%.

We put three pieces of sun-proof clothes folded, into two layers, the test results are: long-wave ultraviolet transmittance almost halved, "days of silk" sunscreen clothing for 5%, cotton 7%, chemical fiber 14%.

"The thickness of the material has a great effect on the barrier of light, in general, the thicker the material, the better the blocking effect." Said Ye Linhua, an associate professor.

It seems that these three pieces of sunscreen clothing have the so-called sun protection effect, then they and ordinary fabric than what?

We randomly found one of the most common cotton-white T-shirts from a colleague's closet, and it turned out to be an eye-opener.

Only single-layer cloth, white cotton t-shirt long wavelength ultraviolet transmittance is only 7%, easy seconds to kill three pieces of sunscreen clothing!

Because the labels on the three sunscreen suits do not have any sunscreen material or paint instructions, it is a special clothing, or a common clothing, we can not distinguish. But Ye Linhua, an associate professor, said that any kind of clothing has a certain sunscreen effect, if no special needs, an ordinary T-shirt can completely help us reduce ultraviolet radiation.

Black T-shirts are more sunscreen than white T-shirts

The price is hotter.

Summer wear clothes, we often feel more cool white than black, the two colors of clothing, sunscreen effect who better?

We found a black cotton t-shirt, which is the same thickness as the white T-shirt above, and it turns out that a single black T-shirt has only 4% uva transmittance.

Ye Linhua, an associate professor, said that the darker the color, the greater the absorption of light. Light on white clothes, part is reflected, part of the transmission, so, wearing white clothes, it will be cooler, but the ultraviolet rays may be transmitted to the skin, and in black clothes, the light is basically absorbed out, although the effect of blocking ultraviolet rays is better, but the price will feel more hot.

Finally, we randomly measured two summer girls must have silk scarves and stockings.

The black silk scarf's ultraviolet transmittance is 37%, while the black stocking is 13%. There are male colleagues joking: it seems that beauty around a silk scarf sunscreen, as well as a set of stockings useful.

Through this experiment, "Curiosity Laboratory" for you ladies summed up the following principles of sun-bathing

1. Cover tightly, wear thick is kingly;

2. The darker the smocks color, the better the sunscreen effect;

3. According to the "assessment of the UV resistance of textiles", the UV protection coefficient upf>

30, and UVA (that is, long wavelength ultraviolet) transmittance of less than 5% of products, can be called "Anti-ultraviolet products", the label will generally have "upf30+" logo; So, when you buy related products, be sure to carefully check the labels and sunscreen index.

11:05, turn on the TV, lock the Zhejiang public channel, the Express Time Curiosity Lab teaches you to dress well in summer to prevent sunburn.

This experiment specially thanks Zhejiang University Optics Research Institute's strong support.

According to City Express reporter Zheng Jianfang Spengfei