Working Knowledge: Cool Shirt; October 2003; Scientific American Magazine; by Mark Fischetti; 2 Page(s)

Sweat cools your body as it evaporates from the skin, but clothing traps that moisture, raising body temperature and causing you to sweat even more. To help, garment makers are infusing the athletic-apparel market with "moisture management" fabrics that wick away sweat and dry quickly-and these are just the first of high-tech clothes to come.

Several factors enhance fabrics such as Coolmax from DuPont and Moistex from Asahi Kasei. Manufacturers are extruding advanced polyesters into fibers with a moisture content as low as 0.5 percent, versus 4 percent for nylon and 6 to 7 percent for cotton, so that they wick and dry more quickly. New extrusion techniques also allow makers to produce fibers with unusually shaped cross sections [see illustration] that channel away sweat. Crafting the coolest fabric "is a balancing act of many properties," says Michael Hunt, senior research chemist at DuPont Textiles and Interiors in High Point, N.C.