As the weather gets colder and colder, “long Johns”, which used to be despised by young people, has suddenly become popular. Topics such as “Hainan Province’s sales growth rate is higher than that of the three Northeast provinces” and “long Johns provide a sense of security in winter” have successively hit the hot list. Long Johns have become a fashion item, and “spontaneous heat” is undoubtedly the first contributor. They look light and warm, which is why they are popular among young people. But do these so-called “high-tech long Johns” really work?
According to the law of conservation of energy, heat cannot be created out of thin air. At present, there is no material in the world that can really heat itself, so there is no clothing that can create “spontaneous heat” out of nothing.
So are spontaneous fever underwear a complete hoax? Of course not. There are many kinds of thermal fiber materials that can provide us with a little extra warmth under certain conditions. For example, photoheating fibers absorb sunlight and reflect thermal radiation from the body; Electric energy heating fiber is hot when energized; Phase change fibers use material phase change to release or absorb latent heat to regulate temperature. Clothes made of these materials do not have to be too thick to keep them warm. The most commonly used heating mechanism in daily clothing is “hygroscopic heating”. The fabric can absorb the moisture emitted by the body after contact with the body, and convert the kinetic energy of the water molecules discharged by the body into heat energy, thus increasing the body temperature.
The constantly evolving long Johns are the epitome of the garment industry’s embrace of technology. The “black technology” represented by “spontaneous fever” makes more and more young people fall in love with long underwear, spawning a number of new brands that take into account both warmth and beauty, and forcing the old domestic products to innovate and follow the trend. “Golden velvet”, “pearl velvet”, “wool bamboo charcoal heat storage fiber”, “light and warm”, “self-heating underwear” and other high-end and mysterious long Johns compete to come out, more and more popular, their prices also rise.
Data from a large platform showed that the number of searches for long Johns in late October increased by 230% compared to the middle of the month, and users under the age of 35 accounted for 51.3% of the search. Search online for “black science and technology thermal clothes”, you will find that the price of thermal clothes, thermal pants more than 200 yuan.
On the other hand, the price of such a high “black technology” long Johns, warm performance is really so good? According to media reports, the Zhenjiang Consumer’s Association commissioned the Jiangsu Institute of Textile Product Quality Supervision and Inspection to test the frequently advertised functions of “heat preservation rate, heat transfer performance, moisture absorption and heating”. The investigators purchased 7 pieces of “self-heating” thermal underwear on 6 platforms respectively. However, from the implementation standards of the products, it can be seen that although the brands all play the banner of “warm” and “self-heating” in the promotion, the implementation standards of most brands have nothing to do with “thermal underwear”. The person in charge of the Zhenjiang Consumer Association said that the thermal underwear of the stores on each platform had a certain degree of exaggerated publicity.
Even if it is in line with the current industry general FZ/T 73036-2010 “hygrothermal knitted underwear” standard of long Johns, it may not be able to achieve the thermal effect in the publicity. First of all, its function will be affected by the environment, for example, in a very dry environment, there is no heat absorption ability; Secondly, the fiber moisture absorption and heat release is a dynamic process, which is not easy to maintain a constant temperature. If the moisture cannot be timely discharged, the fiber “absorbing” moisture will bring discomfort to the wearer.
In summary, although the “spontaneous hot” long underwear does have some advantages, but consumers should not encounter “black technology” on the head, easily be processed by the concept, gimmick confused, but should choose according to demand, rational purchase.
Post time: Nov-23-2022