The cold winter suddenly comes, and with the sudden drop of temperature, keeping warm will be put on the agenda again.

Speaking of things that keep warm in winter, it is natural to mention thermal underwear.

Every winter is the hot season of thermal underwear, especially the self-heating thermal underwear, which claims to have "black technology". It is hot as soon as it is worn, and it has been sought after by many people, and its sales volume is also considerable.

So, is the heating effect of this kind of thermal underwear really as magical as advertised?

This will tell you the truth, these are just another manifestation of warmth, not black technology!

Underwear cannot heat itself. Searching for the keyword "self-heating thermal underwear" on an e-commerce platform can find nearly 20 pages of related products. The styles are similar, but the prices are uneven, ranging from ten yuan to several hundred yuan.

According to the product details page of a thermal underwear, it can be seen that it can "self-heat" because it uses a kind of "black technology" heating fiber, which can lock the temperature in technology and heat itself up to 8.6℃.

Is it really that amazing? Does the secret of clothes heating really lie in the use of "heating fiber"?

Don't!

As for the thermal underwear that can heat itself, experts have already rumored before. "heating fiber" is just a publicity stunt of merchants, not black technology.

No fiber can spontaneously heat up, but we are misled by the principle that most fibers can "absorb moisture and heat up".

The stratum corneum on the surface of human skin will expel water. Human skin emits water vapor, which will dissipate heat after liquefaction, and fiber plays a role in absorbing moisture and heating by using the gas-liquid change of water.

When the fiber absorbs water, the hydrophilic groups in the fiber molecules combine with water molecules, and the kinetic energy of the water molecules decreases, and at the same time it is converted into heat energy and released.

Among different fibers, wool, modal and viscose fiber have better moisture absorption and heat generation effect, while ordinary acrylic fiber and polyester fiber have worse moisture absorption and heat generation effect.

The thicker the fiber of the same fabric, the better the moisture absorption and heating performance.

Therefore, these popular "self-heating" thermal underwear can't really heat out of thin air, nor are they high-tech fabrics. These are marketing gimmicks!

At present, there is no national standard for heating underwear in China, but only a textile industry standard FZ/T 73036-20 10 "Moisture Absorption and Heating Knitted Underwear".

It is stipulated that moisture-absorbing and heating underwear should be made of moisture-absorbing and heating materials. Under the specified experimental environment of temperature and humidity, the fabric can meet the following two temperature increases:

First, the highest temperature appreciation is not less than 4℃;

Second, the average temperature rise within 30 minutes is not less than 3℃.

Only underwear that meets the above two points can be considered as moisture-absorbing and heating underwear.

Among them, the average temperature rise within 30 minutes is the comprehensive evaluation basis of clothing moisture absorption and heating performance, and the larger the value, the better the moisture absorption and heating performance of the product.

So if you want to buy this kind of thermal underwear:

The first thing depends on the material of the clothes. Try to choose fabrics with good moisture absorption and warmth retention, such as wool, modal, viscose fiber and acrylic fiber.

The second is to look at the product details page. Whether there is a test report according to FZ/T 73036-20 10, and whether the products that can prove its moisture absorption and warmth retention effect are selected.

In addition, you should choose formal channels and brands when buying, and don't simply choose according to the price.

To sum up, don't be fooled by the so-called "black technology" stunt. After all, who can't talk big? Instead of spending more money on an insecure "self-heating underwear", it is better to wear more layers.

Similarly, some corsets/corsets on the market also promote "black technology graphene", which can burn fat to shape the body, resist aging and other special effects. After spending money, it is actually an IQ tax.