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Research and Innovation

TPACC Researchers’ Test for Activewear Cooling Efficiency Accepted as Industry Standard

Sophie Guevel (left) holds part of a blue machine and is turned to another person talking to them.

By Sean Cudahy

We’ve all experienced it, whether on a hot summer day, or during and after a workout. While outside in the heat or while exercising, clothes get sweaty and uncomfortable. Then, as the air conditioning blasts on the car ride home, your damp shirt suddenly becomes quite cold as it clings to your skin.

It’s a plight at the center of a novel test developed at the Textile Protection and Comfort Center (TPACC) of NC State University’s Wilson College of Textiles. Designed to measure a fabric’s evaporative cooling efficiency, the TPACC research team’s work recently received a significant form of validation. ASTM International, the globally recognized consensus standards organization, adopted the new TPACC method as a standardized test for the development of clothing materials. The test could, someday soon, be a go-to option for the activewear industry.

The breakthrough could prove useful to companies in evaluating the true effectiveness of their products, particularly as it relates to keeping athletes and other users cool and comfortable, whether they’re running, lifting weights, competing, or otherwise out in the heat. Ultimately, it should be also a “win” for consumers deciding what product to buy.

“We get a lot of companies wanting to make claims about, ‘This fabric can regulate temperatures,’ or ‘keeps you cool,’ or does some other miraculous thing,” TPACC Operations Director Shawn Deaton says. “If you have a standard method behind any of your claims, it gives your claims a lot more strength.”

Filling an activewear industry gap

In the past, TPACC researchers say, companies have developed athletic-centered clothing while relying on tests that measure just one factor contributing to a product’s cooling capacity, such as its breathability or effectiveness at wicking sweat away from the skin — components of comfort, to be sure, but far from the only factors.

As such, there’s been a “critical gap,” notes Deaton and Barker’s September 2022 journal article in “Medical and Science Technology” explaining their findings. It’s a gap, they believe, their new test method fills.

A person lifts up a clear hinged top to a container containing blue fabric. The container is part of a larger piece of metal testing equipment.
The hot plate and chamber that TPACC used to develop its new testing method.

“There are very few tests that have ever really looked at the effects of evaporative cooling itself, and this test method does,” says Roger Barker, TPACC director and professor in the Wilson College of Textiles Department of Textile Engineering, Chemistry and Science.

The TPACC test evaluates both how effective a fabric is at absorbing heat during the active sweating phase, and how efficiently moisture is then evaporated from the fabric after the activity ends.

Put more plainly, the test measures not only how well, say, an activewear shirt, keeps you cool while you’re exercising, but also how quickly it dries after the workout — a key factor in determining whether you end up feeling “cold and clammy” during the air conditioned car ride home, Barker says.

A test driven by simulated sweat

Developed in TPACC’s climate-controlled laboratories, the test method uses a “hot plate” situated next to a piece of fabric to simulate a human sweating underneath a piece of clothing. Inside a chamber, researchers supply liquid to the bottom of the fabric and measure the latent heat the product absorbs during the ‘active sweating’ phase, as well as the efficiency with which the moisture then evaporates — all in a continuous, one-step procedure.

With an eye on the most common types of athletic wear products on the market, TPACC’s tests compared the cooling efficiency of 100% cotton fabric product material with that of polyester fabrics treated with a wicking finish. The tests found the latter fabric, similar to many ‘dry fit’ products today, was more effective through both facets of cooling.

Part of a larger, comfort-driven mission 

TPACC researchers hope this test will assist companies in the activewear industry in evaluating the true cooling capability of their products, ultimately bolstering marketing claims and making for a more positive end result for the wearer.

“It could be used by industry to develop, for consumers, better fabrics and clothing for activewear, sportswear, and many other applications,” Barker says.

More broadly, the development of this test method also underscores the cutting-edge research produced by faculty experts alongside students at TPACC, a world leader in laboratory-based instrumented systems with several core focus areas ranging from flame, heat and chemical protection to comfort performance.

“There are very few tests that have ever really looked at the effects of evaporative cooling itself, and this test method does.” – TPACC Director Roger Barker

“It just shows that we’re always evolving and trying to improve what’s out there in the marketplace in terms of test methods and ways of evaluating comfort,” Deaton says.

While ASTM International accepted the test method as an industry standard in February 2023 following several modifications and improvements, Deaton, Barker and their team aren’t done with their research. They’re hoping to eventually support their findings with an actual wear study, during which human volunteers would wear particular garments in a controlled environmental chamber, and report on the products’ cooling performance.

“We still need to look at how our research translates,” Barker says. “But based on our experience, we’re very, very excited and hopeful about this.”