Wetting and Wicking -2

The human body is exceptionally self-regulating and sweat is produced to keep the core temperature down. During athletic activity, the human body produces heat and a certain amount of water vapour. If the heat emission is no longer sufficient to keep the core temperature of the body at about 37°C, the body will also produce liquid sweat. The optimum form of sweat utilization is the evaporation of moisture directly from the skin to be released as water vapour. This is true because most of the heat energy needed to evaporate the moisture is extracted from the body causing body temperature to drop. Only via the evaporation of liquids can the body efficiently cool itself at high physical loads, which has served as a primary motivation for an increasing interest in the transport of liquids through clothing systems5. Also, the heat flow from the skin through the clothing can be considerably greater when the clothing is wet, since water decreases the thermal insulation of clothings6. This happens because water has a greater thermal conductivity than air. Matter of fact, water-cools the body twenty-five times faster than air. That is why if someone were to place their hand in a bath of water at 40°F it would feel colder than air at the same temperature. In normal stationary conditions, the human body produces little sweat or saturated water vapour. Thus, the wearer may not experience any significant difference in comfort while wearing clothing made of natural or synthetic fibers, which have different water vapour transmission characteristics1. It has been shown though, that the quantity of sweat produced by test subjects wearing clothing made of cotton was less than that with a Polyester article 4. This happens because most synthetic fibers are not adequate conductors of heat, they carry warmth away from the body and are favored for use in hot weather. Consequently, most natural fibers absorb moisture and dry very slowly. The moisture retained in the fabric can cause a “post exercise chill” in a rest phase if the clothing is in contact with the skin. This “post exercise chill” can be exceedingly uncomfortable and can lead to dangerous hypothermia. If one can wear clothing next to the skin that does not pick up any moisture, but rather passes it through to a layer away from the skin, heat loss at rest will be reduced6. Most synthetic fabrics have low absorbency as well as excellent wicking properties that make them more comfortable to wear, since perspiration can travel to the surface of the fabric where it evaporates. In order to keep the body dry, the fabric must be able to transport the moisture away from the skin either through diffusion or wicking. Wicking has become a major topic in today’s athletics, which has given birth to many new companies and products. From fibers to apparel, these companies are flooding the athletic market with products that claim to keep the athlete dry and comfortable. Companies like Under Armour, Coville, and DuPont have emerged into the athletic apparel market with products that are claimed to revolutionary.

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