You can always throw a few chemicals into a synthetic fiber and call it stink-free, but if you have sensitive skin those chemicals can cause rashes and other problems. And merino smells just fine until you get really wet and sweaty and then youll begin to smell like youve just wandered onto a sheep farm. So your best all-natural bet is bamboo.
The reason bamboo is odor- and bacteria-free? In the wild bamboo is fighting a constant battle with insects and microbes that want to destroy it, so over the years it has evolved a set of properties to combat these terrorist attacks. According to a recent study performed by the Japanese Textile Inspection Association, bamboo has about a 70 percent antibacterial efficacy without the need for added chemicals. These antimicrobial qualities have a shelf-life of about 50 washings.
Kombi's bamboo LS crewneck ($55) or zip top turtlezip hybrid ($60) is everything a baselayer should be. Its so comfortable, in fact, that Im wearing the crew (which is 48 percent bamboo, 48 percent Coolmax, and 4 percent Spandex) right this very moment. It feels soft and silky next to my skin, and even after about 10 washings, Im still stink free.