Waterproofing running shoes is actually pretty easy. Theoretically, you could strap two plastic bags over your feet before sloshing around and stay perfectly dry. But that’s only half the equation, which is why the fabric giant GORE-TEX has been in business for more than 50 years. You can keep your feet dry on your own, but it takes a proprietary membrane and a battalion of tests to also keep them comfortable. GORE-TEX doesn’t actually make its own branded running shoes. It partners with companies like Brooks and Saucony; they design the shoes, GORE-TEX keeps the water out.
It’s a simple promise that requires complex collaboration—one that we wanted to learn more about. So, we sat down with Kirk Christensen, GORE-TEX's global footwear product specialist, who leads a team in charge of infusing waterproof tech into running shoes – so you can’t use soggy feet as an excuse to not head outside.
Men's Fitness: How does GORE-TEX technology work? What’s actually making the water stay outside of my shoes?
Kirk Christensen: What we offer is called a laminate; that's the magical material that is waterproof, yet breathable. Think about the material almost like a chain link fence at a microscopic level. Think of a water droplet as the size of a basketball. Those chain link openings are small enough that the water droplet just bounces against it, it doesn't go through. But the sweat vapor, think of it like the size of a marble. Those marbles are going to pass through the holes in the chain link fence. So the sweat molecules escape through the holes, but the water droplets are too big to get inside.
How difficult is it, really, to waterproof a shoe? What I'm really asking is, why don’t companies just do this in-house?
Brands do try it, but it’s difficult. When you say waterproof, we don’t just waterproof, because you could take a plastic bag and wrap it around your foot to keep water out. It’s waterproof combined with climate comfort. Having the material technology to have both happen; that is something that we are experts at.
You have to make sure every time you include things you are not leaving any spot where water could enter. Water is insidious. It’s relentless. Where our expertise comes into play then is understanding the entire system. It’s waterproof, it’s comfortable for the consumer, and it’s durable for the life of the shoe. When you combine all of that, that's pretty daunting for a brand to go and say, “I'm going to do that on my own now.” Some go there, and what you might get is part of that story. So you might get a waterproof piece but it’s not durable, or maybe it’s waterproof but not climate-comfortable. To get all three pieces, that’s the magic of it all.
GORE-TEX has become pretty famous for its rigorous testing. For fabrics, you’ve got a rain room that pummels gear with water. How do you test shoes?
There’s so many different ways a shoe could fail waterproofness, so everything we do when testing is very holistic. We use flex testing to simulate activity or use of the shoe. We will flex it for tens of thousands of movements just to simulate how that shoe is going to operate over time. We also do other types of very extreme testing like centrifuge testing; we spin the shoe around at a really high speed, ensuring water cannot get inside that shoe anywhere.
You build running shoes for your day job, but are you a runner yourself?
If you look at my office, first of all, I have every possible shoe surrounding me and I love it. I run in every type of shoe. I product test all the time because I want to experience what the consumer experiences.
How many pairs of shoes do you think you have?
Hundreds, easily. Also in my closet at home; hundreds, easily. I live and breathe it. It drives my wife crazy. We always have to add more shelves.
I think ultimately if we are putting this on people's feet, I feel accountable to that. I need to make sure personally that I want to experience what the consumer is experiencing. There’s an expectation that we have to put ourselves literally in the shoes of the consumer, because at the end of the day we are trying to enhance their life. Go for a run on wet grass, and very quickly you’re going to notice your feet are wet. You start to focus on that and it’s taking away from what you are trying to focus on. If I can prevent that then that's success for me.