For outdoor hiking, backpacking or camping trips, I always hear people saying Cotton Kills. That means don't wear cotton anywhere (underwear, shirts, pants), and no cotton blends. Usually it's given as a strict, no compromise rule if the temperature is somewhat cold < 40F.
I understand that cotton retains moisture (sweat, rain), which makes it less thermally insulating, harder to dry out and heavier. This can lead to hypothermia, pneumonia, etc. Thus, synthetic materials and wool are preferable. But by how much?
Are there any studies showing how much more thermally insulating damp synthetics or wool are compared to damp cotton? I'm curious if cotton is just like 50% worse or more like 5x worse. That might allow you estimate, for example, that you could survive 5 hours with wool vs. 2 hours with cotton under certain temperature conditions.
