We've written it before and we'll write it again: a good flannel shirt looks as good in the office as it does in the mountains. Layered appropriately, such a top can be worn in sub-zero temperatures, as well as into the 70s. A good flannel shirt is capable of keeping you dry in rain and snow, or when you’re getting sweaty. It can be worn daily for a decade or more.
The trouble is, most of the “flannel” shirts you see mentioned on outdoors websites like this one can’t do those things. And that’s because most people don’t understand that flannel is not a pattern—it is a material.
Why Flannel Works
It’s believed that that material was originally developed in Wales, in response to that nation’s notoriously unpredictable cold, wet weather. Made from long, fine sheep-wool fibers that were spun into a tight yarn, then woven to form a dense fabric, flannel was strong and utilized the natural properties of wool to provide a barrier against the weather and stink. That tightly-woven wool fabric was then napped to expose the ends of the fibers, giving the resulting material a hairy texture. This process adds warmth by creating loft that traps air, makes the fabric softer, and increases moisture wicking.
To this day, flannel must be made from wool if it’s going to be as comfortable, functional, and durable as the material is reputed to be. You see, wool is something of a wonder material. You may think of wool as water-resistant, because you can often see rain bead up and run off its surface. That’s due to the tightly-woven nature of the garment, along with the scaly outer layer of the fibers, which is hydrophobic. The inside of wool fiber is actually hydrophilic, meaning it attracts and absorbs water molecules. Once inside, water vapor is trapped within the wool fiber, making the material dry to the touch, even when it’s soaking wet. Splash a bucket of water on a proper flannel shirt and it stays dry.
Something even cooler happens when water vapor gets inside wool. There, H2O molecules bind to the microscopic structure of the fibers, breaking the bond between the hydrogen and oxygen molecules in a chemical process that actually produces a tangible amount of heat. In warm weather, wool absorbs water vapor from the wearer’s body, then releases it into the atmosphere through evaporation, providing a cooling effect.
Because the natural crimp of its fibers traps pockets of air within a tightly woven fabric, wool is a good insulator. It holds the heat generated by the wearer in cold, damp conditions, but when it’s hot out, it traps the cool, dry air created by evaporative cooling, thus insulating the wearer’s body from the heat. Unlike other materials, that process takes place not just through tiny holes in the fabric, but through the wool fibers themselves. This makes the material exceptionally breathable.
Wool is also naturally antimicrobial, thanks to the lanolin wax that occurs in its fibers, which kills bacteria it comes into contact with. This, combined with wool’s ability to manage moisture, creates an environment that's not at all friendly to odor-causing bacteria. Which is why wool doesn’t stink, ever after days of wear.
That means you can wash garments made from wool far less often, which is part of why garments made from it are so long-lasting. The other factor in wool’s durability is that it’s largely composed of keratin, which can stand up to stretching, bending, and abrasion far better than other types of fiber.
Some properties of wool have been replicated by cheaper synthetic materials, but no single synthetic fiber can achieve all the things wool can, nor is any synthetic fiber used in clothing as durable as wool. Cotton fibers work in almost the opposite fashion as wool, absorbing vast quantities of water, holding onto it, then exposing the wearer's skin to that moisture. Cotton, for instance, has been blamed for deaths caused by hypothermia in cold weather and feels clammy and gross in hot weather.
That’s why it’s positively insulting to call any material made from cotton or synthetic fibers “flannel.” Flannel should only ever be made from wool. To suggest that other materials can work as well, by giving them that name, is dangerously misleading.
Unfortunately, cotton and synthetics are cheaper to produce than wool, so now most supposedly “flannel” shirts are not made from the correct material and the brands who make them intentionally mislead consumers by suggesting their “flannel” shirts are good to wear outdoors. Allow me to provide some more appropriate guidance.
Real Flannels You Should Actually Buy
The Classic: Pendleton Lodge Shirt ($135 to $145)
Made from American-sourced fabric, the Lodge is Pendleton’s classic, no-nonsense flannel shirt. The Oregon-based company has been in operation since 1863 and still employs a 100-percent wool construction for this shirt.
The Solid: Fjallraven Ovik Re-Wool Shirt ($160)
Fjallraven employs sustainable, recycled wool for the construction of this chunky flannel and adds abrasion-resistant polyamide panels to the shoulders, yoke, and elbows to make it even more hard-wearing. Adding to the cold-weather ability of the heavy material, there’s a hidden button under the collar, enabling you to turn that up and fasten it closed to protect your neck.
Made From Merino: Icebreaker Lodge Shirt ($180)
Merino fibers are smaller in diameter than most other types of wool, meaning they’re softer. Merino can also be woven more finely than larger wool fibers. Together, that makes the fabric more comfortable when it’s next to your skin. That’s good, because this is a lightweight flannel that looks dressy, meaning you can also wear it in less outdoorsy environments.
The Sporty One: Kitsbow Icon Shirt V2 ($220)
Made from heavyweight Pendleton wool, Kitsbow adds a tailored fit that flatters athletic bodies and abrasion-resistant panels on the shoulders and elbows. As good a soft shell as you’ll ever find, in a package that looks, and feels like a button-down shirt.
The Shirt-Jacket: Smartwool Anchor Line ($180)
Made from an 80 percent merino, 20 percent nylon blend, the Anchor Line is thick, warm, and soft. It’s cut very generously, so you can wear it over the rest of your clothes, but I found mine a little too boxy and had a tailor slim down the torso a bit for a more flattering fit. That was the best $20 I ever spent, as it made this shirt-jacket my go-to layer for more than a year. Sadly, it was misplaced when I moved to Montana this summer and my wardrobe just isn’t the same without it.
How to Get the Most from Flannel
You can easily screw up most of the benefits flannel brings by wearing it with the wrong layers. Wearing a cotton t-shirt under a flannel will, for instance, impair wool’s ability to wick water away from your body. Wearing a flannel shirt under a less-than-breathable outer layer will do the same.
To get the most out of a flannel shirt’s abilities, I like to pair it with more wool. Typically, that means layering a thin merino t-shirt (Trew makes its from NuYarn, which lasts longer than other merino fabrics) underneath and putting a thick wool sweater on top. If I get too hot, I can just strip down to that T, while the sweater will keep me warm down below freezing.
Because flannel or a good wool sweater can easily shed light rain, I’ll skip the shell in favor of maximum breathability unless it’s really coming down. (If you must add a hardshell, make it one made from Polartec Neoshell, which passively flows air, making it much more breathable than most alternatives.)
Need even more warmth? Over that sweater, a good down vest works best. Not only does that free your arms for movement, but it adds insulation where you need it, while allowing the wool garments to exhaust water vapor through your arms and armpits unimpeded. Going even colder? A heavyweight wool jacket will complete your all-wool upper body system. This season, I’m wearing the Filson Lined Wool Cape Coat, which adds a layer of wool sherpa insulation for extreme warmth.
A flannel shirt might look just at home in Brooklyn, but so long as it’s made from wool and layered properly, it’s the absolute best thing you can wear outdoors, too.