Computerized Knitting. Breathability of a fabric is important, with air flow through it carrying heat away from the skin. Favelle cites Ministry of Supply, a Boston firm founded by former MIT students, that employs a variation of 3D printing technology. This innovative knitting process creates additional space between strands of material, thus promoting breathability. “The result,” Favelle reports, “is a garment that feels slightly thicker than a standard shirt, as if wearing light padding. Yet it also feels cool, even under other garments.”
Space Tech for the Street. Another high-tech approach evolves from NASA “phase-change materials” designed to cool astronauts. The fabric has embedded wax and other materials that act as heat sinks, thus providing a lasting cooling effect.
To Wick or Not to Wick. Favelle notes that “Sweat is the body’s natural cooling mechanism,” though garments are marketed to wick the moisture through to keep the wearer dry.
However, according to Glen Kenny, professor of physiology at the University of Ottawa, “There’s a misguided belief that wicking away that sweat from the skin is somehow going to keep the body cool.” Favelle explains, “The closer to the skin that evaporation takes place, the more heat energy it consumes in the process; when clothing moves sweat away from the skin, it keeps the body dry but renders evaporation less efficient at cooling, Dr. Kenny said.”
Tradeoffs. It’s a matter of thermodynamic balance and sartorial tradeoffs. And then there’s environmental aspects of fabric production: “In some cases,” Favelle notes, “making clothing better suited to heat can exacerbate other climate problems. One of the most breathable natural fibers is cotton. But growing enough crop for one pound of cotton fiber requires almost 350 gallons of water in a good year, according to data provided by the Agricultural Research Service at the United States Department of Agriculture.”
What’s more, Favelle says, “The best type of cotton for heat is often called Pima or Egyptian cotton, which makes garments that are thinner and lighter. Yet growing Pima requires even more water than lower-quality cotton, according to the U.S.D.A.—in some cases, twice as much.”
And Then There’s Petroleum. Favelle observes, “Still, natural fibers like cotton are at least biodegradable. Sweat-wicking polyester, by comparison, is made from petroleum, and can take decades or more to decompose—another challenge for clothing manufacturers already under pressure from environmentalists.”
I note that my favorite T-shirts are 100-percent cotton. However, I cannot speak for the ink of “RUN\DOS\RUN” and other sartorial messaging. ds