Originally Posted by
Seattle Forrest
Try getting cotton wet ( rain, sweat, whatever ) when it's cold ( < 40 F ) out. Actually, don't; any hiker will tell you "cotton kills." Cotton socks won't kill you, because you won't get lost in the wild in them, but they're pure agony if it starts to rain in December. Wool keeps about 80 % of its insulating power when it's saturated, while cotton steals the heat from your body.
Not to mention that wet feet tend to blister, it's bad for the skin (see trench foot post as well), and your feet will literally freeze in cooler temperatures. I actually have to be really careful in lower temps because I have something called Raynauds where if my feet or other extremities get too cold, then the capillaries overreact and squeeze way down, ostensibly shutting off the blood supply to those areas. I cannot ever, ever wear cotton socks in lower temperatures on the bike or anywhere for this reason. My feet sweat, cotton soaks up the sweat, feet get cold, capillaries shut down, feet turn purple and lose all feeling. Totally sucks.
Ever notice how long you have to put a cotton towel in a dryer? Compare that to something poly. My poly stuff dries out in an hour in the open air. A cotton towel would take 4-5 hours in a stiff breeze.