The Smelly FactorAs mentioned earlier the marketing guys saw this as an opportunity to claim that their product does not smell. I can simplify this decisions for you. If the fabric is synthetic it will end up smelling, if its wool it won't. Whatever you do to polyester of polypropylene you can't avoid it taking on that really horrible sweaty smell. Of course it can be washed out but its back again by the end of the day. Merino wool on the other had can be worn for days without getting significantly pungent. Right: Smartwool lightweight underwear. Can be worn for days on end without smelling. To simplify things I've broken the main base layer contenders down into the three base fabric types, listed their properties and potential usage. Make your buying decisions based on the fabric and not the brand name. Mitigating factors might be additional treatments or weave but be wary of over ambitious claims.
|Absorbs minimal moisture, although this does not mean it won't wick. Moister evaporation can be achieved by having an open or textured weave.||Actively absorbs moisture which means it soaks up plenty of sweat but it's not particularly good at drying out quickly once wet.||Actively absorbs moisture and takes a long time to dry out.|
|Has a rougher texture than polyester and not as comfortable next to the skin.||Has a softer feel than polypropylene especially in the fine weave varieties||Really comfortable to wear next to the skin. Lots of people wear it as every day clothing rather than reserving it just for trips into the hills.|
|Gets smelly especially over multiple days.||Gets smelly, and in time to the point that you could be mistaken as a gentleman of the road. Smells a lot worse than polypropylene (subjective opinion).||Does not get smelly and can be worn over multiple days without any significant smell building up.|
|Most suitable for high energy sports where you might be sweating a lot. Because it doesn't aborb sweat its stays dryer for longer and therefore warmer. Also useful for situations where there is a lot of water about such as kayaking and extended trips in cold climates where you are using vapour barrier layers.||Works best as loose fitting summer t shirts for climbing or walking. It does not perform as well as polypropylene as a thermal underwear layer .||Most suitable for winter climbing, skiing and walking where you might be working hard but not sweating profusely.|