Here are some thoughts on fibers and fabrics from a guy who once never would have gone for anything but loose, 100%-cotton boxers. I've done a fair amount of traveling, hiking, and backpacking, so I wrote these out for a friend who was shopping around: Cotton: Really comfortable when dry. Medium weight. Feels great against the skin, especially when loose. Breathes beautifully. Slight delay before it starts to stink. Not really the best to re-wear once perspired-in. Launders well BUT takes forever to dry. Gets damp easily, especially from humidity/perspiration and remains wet next to skin, going possibly from slight chafe to extreme irritation -- plus drags heat out of skin in cool weather leading to significant hypothermia risk. ("Cotton kills in cold", as we say in outdoor pursuits.) Tends to cling, ride up, bind, so you want them loose; never tight. Besides, 100% cotton doesn't stretch. Durable, even able to take chlorine bleach. Cotton Flannel: Normally associated with winter but I found out a long time ago that I prefer cotton flannel boxers in humid weather because the nap of the fabric eliminates the tendency to cling/bunch/ride up. Less durable, though, than standard woven cotton shorts and takes even longer to dry. Merino Wool: Expensive (probably the most-so) but has all the advantages of cotton with none of the drawbacks. Absurdly soft and comfy, though can still ride up, cling, or bind in the crotch, I suppose. (I'm guessing, as I've never had merino wool in shorts, just in other items.) Dries FAST. Impressive ability to wick water away from skin. (Conveys a massive drop in hypothermia risk in cold weather). Most amazingly of all, can be worn and sweated in day-after-day for WEEKS and still smell clean, even while its wearer rots away, getting riper. (Daily showers/sponge baths/clean-ups are advised to reduce the stench of the merino's occupant but at least his clothes won't stink and he won't be forced to do laundry.) Fairly durable but it's knitted, so avoid snags. Also, can be munched by moths, so must be be protected whilst in storage. Woven Silk: Extremely lightweight. Nicer against the skin than anything else known to man (or woman). Dries faster than air it's so almost impossible to get it to cling and ride up. No matter how tightly you wear it, it always seems to remain loose, so it keeps the next layer of clothing draped naturally and easily on the body and keeps the wearer comfortable. Kicks cotton's butt for looking good and basically eliminates any evidence the wearer has on underwear (one reason women go for silk lingerie, panties, &c). A plus: It's durable, so durable that, centuries ago in Asia, they built suits of armor from this stuff. Knitted Silk: Used for extremely light thermal layers (long Johns, except they're like stockings). My old choice for a winter thermal layer, but one I've since replaced with merino wool blended long pants. Polyester and Poly-Cotton Blends: Polyester, when blended with cotton, reduces wrinkles and makes the fabric more silk-like to the touch. Dries somewhat quicker than 100% cotton -- but, then, what doesn't? Drawbacks number 1-through-1000: The stuff doesn't like to breath, especially when woven. (100% Polyester knit shirts can be comfy in damp weather when no other layers are involved.) It's like a Baggie against the skin (it's cotton with plastic in it, after all), so you sweat-sweat-sweat and it can be insufferable in anything over 40% (dry) humidity. Stain resistant and easy to launder, so it's long appeared in middle-income office wear for those who have to wear suits and pretend to look clean but who can't afford silk shirts and dry cleaning. (For such dress shirts, I, personally, go for 100% polyester (or silk when I used to be able to afford it). 100% polyester requires no ironing, drip-dries fast, looks terrific. Just stay motionless in humid weather or you'll sweat like a pig in woven poly. Your clothes will still look great; you'll just be bright red with a clammy handshake.) Blends of Other Plastics Such As Nylon, Elastomerics (Spandex), &c: Here's where the Ex-Officios come in. Basically, they don't hold moisture, so they air-dry rapidly when washed and never get damp when worn. Even slightly damp from washing or swimming in them, as I do, they're still wearable in a hurry because of the fast-drying nature of the cloth. The difference between these and polyester is the structure they can build the nylon into: Polyester pills and its tiny fibers are clingy, so friction makes them twirl off the surface and mash into little wads. Polyester fibers basically want to come loose and turn into felt, especially when tangled amongst fibers like sturdy cotton that refuse to let go. But nylon can be woven, crocheted, or knitted into a 3-D, "beefier" structure that has plenty of breathable air space in it, like these ExOfficio shorts, but the nylon fibers hold their structure and resist matting-down into a flat mess like polyester wants to, hence no skin-wrapped-in-a-plastic-baggie effect. The ExOfficios are sold as "travel underwear". They can be ordered as looser boxers or as a tighter boxer brief, like the pair I've had for a year, now. (Oddly, when I checked my new Amazon order, I found I'd accidentally purchased boxers this time instead of a second pair of boxer briefs. They still seem wearable as ersatz swim trunks in a lake when hiking, though they contain more fabric and will take up slightly more pack space. Anyway, I now have one pair of each style in the exact same fabric. Should be interesting to compare. I've not yet worn the boxers, so I'll just write about the boxer briefs. Some of this is going to have to do with the cloth and some with the boxer brief style...) Ex-Officio boxer briefs don't feel like a familiar sort of cloth. It's more like putting on a wrapping layer over your body, more like an object than a fabric. And while the first reaction is to be entirely distracted by how different it feels from standard cotton boxers, the freaky thing is how significantly you forget you have them on once you get dressed. The result is something like, "I am walking around. I am wearing clothes. But the outer layer of clothes are not bunched around me and I am not in direct contact from them." It's kind of as if there is a force field of quiet around you with nothing in it to notice: No itch, no chafe, no bind, no sensation of movement or irritation of any sort. Not even the sensations we associate with dry cotton and call "comfort" (at least until the sweat dampening starts). Just an absence of all of that. Unable to smell bad. Pretty darn durable. With a combination of an easier wash and faster dry than anything else but merino, I can't recommend them enough. Wash 'em at night. Wear 'em within hours. Their instructions read: "After washing this underwear with soap, simply wring it out, lay it flat on a towel, roll it up like a burrito, and stomp on it. Hang dry in a well ventilated location. It should be dry in about 2-4 hours depending on humidity." On the road, I wash them in the shower all the time. Seriously, do people submit video reviews of underwear? Do people pay to see them?
