Long underwear, also called long johns or thermal underwear, is a style of two-piece underwear with long legs and long sleeves that is normally worn during cold weather. It is commonly worn by people under their clothes in cold countries.
In the United States, it is usually made from a cotton or cotton-polyester-blend fabric with a waffle weave texture, although some varieties are also made from flannel, particularly the union suit, while many newer varieties are made from polyester, such as the Capilene trade name.
European manufacturers use wool blends or even 100% wool, usually Merino or other high-quality wool. Some models might include a thin layer of polyester to transport moisture away from the skin. Wool, in addition to being fire retardant, provides highly effective insulation and will keep its insulating properties even when wet, as opposed to cotton.
The type known as "thermal underwear" is made from two-ply fabric of either a wool layer and an artificial fibre, only wool or – again mostly in the U.S. – two layers of only artificial fibres, which uses trapped body heat to insulate against cold air.
The manufacturing foundations of long johns may lie in Derbyshire, England, at John Smedley's Lea Mills, located in Matlock. The company has a 225-year heritage and is said to have created the garment, reputedly named after the late-19th-century heavyweight boxer John L. Sullivan; the company still produces long johns.
In 2004, Michael Quinion, a British etymologist and writer, postulated that the "john" in the item of apparel may be a reference to Sullivan, who wore a similar-looking garment in the ring. This explanation, however, is uncertain and the term's origin is ultimately unknown.
It has also been posed that the term is an approximation of the French longues jambes, which translates to “long legs.”
Long johns were first introduced into England in the 17th century, but they did not become popular as sleepwear until the 18th century. They were first used as loungewear but then later became popular in Truro, Nova Scotia. In 1898, Myles and his brother John had developed a product called Stanfield's Unshrinkable Underwear for their garment manufacturing company.
Long johns first appeared in North America. Frank Stanfield, a Canadian, applied for the first patent for the long johns design. He and his brother started with non-shrinking cotton underwear, and formally applied for a patent for long johns on December 7, 1915, and became the pioneer of long johns.
From 1914 to mid-1918, the item of underwear most purchased by various military forces was a garment known as a union suit - this kind of special cloth, covers body and legs is a combination and the prototype of "Qiuyi(秋衣)", the tops, and "Qiuku(秋裤)", the bottom.
After 1918, countries returned to producing more and more daily usages. European and American countries deepened the industrial revolution in accordance with the idea of assembly line and division of labor. Manual laborers who were physically active were divided into laborers with more upper body activities and laborers with more lower body activities. It then became more and more obvious that "Qiuyi" and "Qiuku" appearing as separated part is better than them showing up as a whole.
After 1940, the United States did not have the perfect indoor heating conditions as it is today, and many people use stoves to heat up the room in winter. At that time, one not only had to wear Qiuyi, Qiuku, or Union suit, but also had to wear a nightcap when they went to bed, and the frequency of bathing was far less than the current time.
During the US-Soviet "kitchen debate" in 1959, Khrushchev questioned the technological level of Nixon's "typical American housing"-judging from the historical reference of long pants, the appliances displayed in the United States might indeed be a bit more advanced.
In China, people use separate words to refer to the two parts of long underwear, and the word choices vary across China. In the northern part, people refer to the top as "Xianyi" and the bottom as "Xianku". People living to the north of the Yellow River and to the south of Yangtze River refer to the top as "Qiuku" and the bottom as "Qiuyi". People living to the south of the Yellow River call the top "Mianmao Yi" and the bottom "Mianmao Ku."
In the early 2010s, a myth spread through Chinese social media that long underwear was part of the Soviet Union’s conspiracy to prevent Chinese military powers from invading Soviet soil in the far east. The myth suggested that the Soviet Union believes that long underwear reduces Chinese soldiers’ adaptiveness in cold climates based on since-debunked theories of Lysenkoism that was popular in the mid-20th Century.
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