>>2807915You haven't been on her emuch, then. Every time this thread pops up, there's a bunch of people explaining. Anyways, it boils down to how the fibers react to moisture. Synthetics don't do anything, and insulate the same amount all the time. So if you move, you get hot, if you stop moving, you get cold.
Cotton, and to a lesser extent, linen, have a fiber structure that collapses on itsself, reducing surface and massively reducing insulation. Hence the "cotton kills" meme (which isn't fully true, btw, cotton shells work fine if you ahve insulation beneath).
The nice thing about wool, alpaca and other animal hair is that it stretches when moist, increasing surface and speeding up it's own drying process, basically. What his means is that if you start to sweat (sweat more, more precisely, since we always sweat a little), wool will increase the speed of evaporation to compensate. To some extent, this allows your body to adjust it's temperature the way it's meant to be, without having to constantly add or remove layers.
From my own experience, a short-sleeved wool shirt with nothing on top or below works fine from ~5°C to ~40°C. Cotton and hemp are too cold around 10°C and unbearably hot and wet above 30°C, and synthetics (polyester, I never bought any fancy stuff) feels basically the same, just without the wet part.
