Recently, I received some adorable new underwear courtesy of the lovely folks over at Dear Kate. And these undies kind of blew my mind.
What’s so interesting about Dear Kate underwear (other than the fact that they’re pretty damn cute)? Allow me to talk about monthly lady times for a moment.
You see, these are designed specifically to be worn during your period and contain a special liner to draw fluids away from your body and repel stains.
Now, I’m a lover of nice underthings. But I also have a lot of b-listers (and c-listers, honestly) hiding in the back that I wear during that time of the month. They are ugly. They are stretched out, faded, and frankly sort of pathetic. I don’t feel great when I wear them, but I always considered it a necessary precaution, especially during the first couple of days.
Having actual nice, pretty underwear that I don’t have to worry about ruining has totally changed my outlook when I get dressed. I had one less reason to feel miserable and gross. I particularly like the new Vera hipster they recently released (I have the orchid color), and want to buy a couple more.
Aside from the great concept and pretty designs, there’s one other thing that interested me about these. It’s such an innovative use of technical fabric, namely polyester.
Dear Kate was developed by Julie, whose background is in chemical engineering. She realized that so may women deal with the problems of heavy periods and overflow, and that new technology in textiles could help.
Julie did the R&D sewing herself, and is still the fit model for the brand. They’re also still manufactured in the US. I love stories like this: a woman sees a problem and how she can address it, and builds her company from there.
This is Julie sewing in the very beginning of the company.
This is Li Ping, one of the sewing operators who currently makes the garments in New York.
So why did Julie choose polyester to make her super absorbent gussets? Isn’t polyester just that cheap synthetic from the 70s? Isn’t it always horribly unbreathable?
For the answer to that, let’s first look at what makes a fabric breathable.
From fiber purist to poly stretch pants
Before I became a runner, I was a fiber purist. I only ever wanted to wear natural fibers and believed them to be objectively superior to anything synthetic.
In day-to-day life, I still wear natural fibers almost exclusively (perhaps with the occasional synthetic blended in, like spandex in pants, or nylon in socks). Generally, natural fibers are more breathable and feel great against the skin.
But when I began running longer distances, cotton no longer cut it. In the winter, I’d have to wear many layers of clothing when I headed out. After running for a while, my cotton leggings and t-shirts would become wet with perspiration, which is dangerous in very cold conditions. In extreme cases, it can lead to hypothermia.
In the summer, I’d sweat even more, and the moisture and salt would rub and grate against my skin, causing chafing. Let me tell you, there are few things less pleasant than being rubbed raw when you are on mile 17 on a hot day. So much pain coming at you at once.
So I began buying workout clothing in moisture wicking fabrics. I noticed that these fabrics were usually entirely synthetic, and I was confused. Aren’t synthetics supposed to be less breathable than natural fibers?
Are natural fibers really more breathable?
It’s true. In general, natural fibers are more breathable.
What does “breathable” really mean, though?
In essence, breathability refers to a fabric’s ability to maintain the equilibrium between the moisture contained in the fabric itself and the air around it. Fabrics that are constantly absorbing moisture and releasing moisture are more breathable than fabrics that don’t.
In practice, what this means is that when there is moisture released from your skin, it doesn’t become trapped in the air between your skin and the fabric.
Take linen, for example. This fiber has been used for centuries in hot climates to keep people cool in even extreme temperatures.
Wool is also very effective at maintaining that equilibrium, especially in thin layers. That’s why merino wool socks can keep your feet cool and dry, even in warm conditions (weird, huh?). Wool is a great all-weather fiber.
Cotton can also be very cool, especially when worn in very thin layers. Cotton is also quite good at absorbing moisture. You probably wear a lot of cotton in the summer for this reason.
Contrast this with a synthetic fiber like polyester. Everyday polyester doesn’t breathe in the same way, leaving heat and dampness trapped on your skin. Yuck.
Cotton will absorb about 7% of moisture, but polyester only about 0.4%. That’s a huge difference. When you buy a cheap polyester dress at Forever 21 and wear it in the heat of summer, you’ll feel that.
So why synthetics?
If all this is true, why choose synthetic fibers at all when moisture is a concern?
Put simply, not all synthetic fabrics are the same, even when they’re made out of the same fiber. Polyester fabrics are not all created equally.
Yes, natural fibers are breathable and lovely in everyday life. But where they are less successful is dealing with very high levels of moisture.
Natural fibers tend to absorb a lot of the fluid, holding onto it instead of releasing it all back into the outside air, away from the body. If you’re sweating a lot (or have a heavy period), the fabric becomes saturated. Not good in either of those situations.
This is where technology steps in, and why moisture-wicking fabrics are often referred to as a category of “technical fabrics.”
These wicking fabrics are made from blends of polyester. Remember what I said above about polyester only holding about 0.4% of moisture? In cheap polyester fabrics, this is very bad for staying dry.
But wicking polyester is woven differently. The weave is extremely permeable, meaning that moisture can pass through easily. The weave is designed so that the bits of moisture are pulled into the small holes in the weave and towards the outside of the fabric, where they can evaporate. Sometimes, additional chemical treatments assist this process (though not always).
So back to the panties.
Because they’re made with wicking fabric, moisture is pulled away from your body, and into the absorbent, thin lining within. They are extremely comfortable and, yes, breathable!
So next time you’re looking at a content tag and think about turning up your nose at polyester, consider whether it’s your everyday polyester or one of these modern fabrics. While you may still prefer natural fibers in everyday clothing (I do), when you have special concerns about moisture, technical fabrics might be the way to go.
PS: You can buy Dear Kate panties over here. They sent me some undies to check out, but they did not pay for this post or anything. I really love what they’re doing with these innovative fabrics!