I read that moisture wicking base layers help keep you warm by keeping you dry, and therefore countering the effect of evaporative cooling.
That made sense to me, until I SPECIFICALLY read somewhere that the base layer, by being close to your skin, is like a 'proxy skin'. It draws sweat into it via capillary action, then distributes that sweat widely to help it evaporate. When the sweat ultimately evaporates, it does so off of the base layer, therefore, the base layer is 'cooled', as opposed to your skin.
That made me wonder though, when the base layer 'feels' the evaporative cooling effect and cools down, doesn't it then draw more heat from your body via conduction, so you should then feel cool as well? Or is the idea that this heat loss via conduction to base layer is much smaller than the heat loss from evaporation would have been, so net a base layer keeps you warmer?
Further, if the point of a base layer is to take on the evaporative cooling effect as a proxy, then I also am confused why a moisture wicking base layer made of synthetic is better than a moisture absorbing cotton undershirt (even though an entire industry says it is). Assuming you're not sweating so much that the cotton shirt can't absorb anymore, if you sweat a little, the cotton absorbs it, then when evaporation occurs, the water evaporates off the cotton, again not your skin, so shouldn't cotton function also as a 'proxy skin'?