How High-tech Fabrics Cool You Down When You Heat Up

The history of cooling fabric goes back to early days of NASA when scientists there were working on how textiles could impact someone in a spacesuit, says Jim Ross, senior vice president of product development with American Textile Company, and makers of Tranquility weighted blankets.

Of course NASA now utilizes other technology in its spacesuits to keep astronauts cool, including cooling panels with liquid-filled channels and a network of narrow tubes linked to a backpack refrigeration unit. This is a far cry from the sleek shirts, shorts and other athleticwear offered today like Nike's Dri-FIT and Adidas Climacool, just to name a few.

"There are a number of different cooling technologies that can be used with textiles," Ross says. They can be divided into two main categories, temperature balance and temperature abatement.

Fabrics that cool using temperature balance focus on wicking. Nike explains on its website its Dri-FIT wicks away sweat and disperses it across the fabric's surface to evaporate faster. Adidas Climacool clothing works in a similar way.

Typically, these fabrics are treated with a polymer, which is a long chain of organic molecules that are assembled from many smaller molecules called monomers. Heat and humidity that your body creates activate the polymer finish, which then moves humidity away from the surface of the fabric, whether it's an athletic shirt or a pair of leggings.

"It's about boosting humidity evaporation," Ross explains. He compares temperature balance to the coolness we experience after a shower as the water (or humidity) evaporates.

Temperature abatement, on the other hand, works by actually transferring heat; this is the type of technology behind American Textile Company's Tranquility Weighted Blanket. In both cases, the way the textile is treated determines how it affects cooling.

With temperature abatement cooling, the textile actually feels cool to the touch, although it technically isn't. The coolness is achieved through the conductivity of the fabric's yarn, which is highly conductive polyethylene (PE). Whereas wicking technology consists of a treatment applied to the fabric, in this case, the yarn itself is made to cool. PE yarn rapidly transfers heat away from the surface.

Ross explains that the transfer process is similar to how different fabric, wood and metal feel to the touch. If samples of these three are sitting side by side, for example, the metal will feel cooler to the touch even though the ambient temperature for all three is the same. But when the heat of your hand is applied, some materials — like metal — will transfer heat away from the surface faster, giving a cooling sensation. PE yarn works in this same way.

A cool-to-the-touch blanket that incorporates a heat-conductive PE yarn absorbs body heat and displaces thermal energy to create a cooling effect. Are you noticing a trend? In both cases, cooling results from transference — either heat or humidity is transferred away from your body.

We mentioned there were two ways to categorize cooling technologies, but there's actually a third — phase change material (PCM). This substance can change — hence the name — from liquid to solid state depending on the temperature. It works to either absorb or release heat. In a mattress or textiles, PCM can regulate heat. For example, the Eli & Elm Whitney Collection bedding is said to provide a cycle of cooling and warming throughout the night, so the sleeper is never too hot or too cold. It works courtesy of small PCM capsules in the fibers of the fabric.

Any of the cooling technologies above will deliver what they are meant to. A textile using temperature abatement will feel cooler to the touch, and if you wrap up in a cooling blanket, the cooler temperature is obvious.

With temperature balance, your body will be cooling, it's just more passive, Ross says. Temperature balance cools for a longer time as it continues to wick moisture away. One fabric feels cool, he says, while the other one works in the background to lower your temperature.

And PCM works in a cycle, so it not only cools, but also attempts to regulate body temperature.

Where are these cooling technologies used? In apparel, almost all cooling technology is dynamic wicking, partly because the PE yarns are not as comfortable against the skin and are more difficult to work with. But Ross says there might be more of the temperature abatement option showing up in clothing in the future as technologists get better at working with it.

But when it comes to home textiles, all types of cooling products are available. For example, the Tranquility brand has both temperature-balancing and cool-to-the-touch weighted blankets. Mattresses and pillows also offer various versions of cooling. Although the marketing terms may change, the mattress will either have a wicking type of fabric, use PE yarn that is cool to the touch or include some type of PCM.

Are these products enough to keep you cool while you're working out or sleeping through the night? In theory, they should all work. But one factor that can affect how cool you feel is how many barriers are between you and the cooling textile.

For example, if you have a cooling mattress, but on top of it are several layers of non-cooling fabrics, you may not reap the benefits. Another thing to consider is that there are two sides to your body — the side on the mattress and the one that faces up. Maybe the mattress is cool, but the blanket on top of you is not. That would also affect your overall coolness.

The microclimate includes what we lie on as well as what is on top of us, Ross says. A top sheet might create a microclimate of heat your body radiates and trap it, but a cool blanket affects the top surface, helping cool you down. The same idea goes for wicking clothes when you work out.

The good news is cooling fabrics keep working while you're using them because they're designed to perform when your body adds a source of heat or humidity.

"It doesn't dissipate or go away," says Ross about temperature abatement technology. "It's activated by your body."

Similarly, wicking technology is dormant until you apply heat, and then it starts transferring. It's all a bit like the question about a tree falling in a forest: The technologies only do their cooling when someone's body heat is there to notice.