This is a good thread to revive. I think there’s a significant difference between those who sweat a normal amount under exertion, and those who sweat profusely nearly all of the time. Unfortunately, I’m one of the latter. For the most part, I stay in good backpacking shape year round and yet I still sweat tons on every hike, regardless of season, pack load, how fast or slow I hike, or ‘layering systems’. It took me a long time to find out what works for me, particularly here in the PNW, where even in the summer a majority of my hikes keep me in the cool forest shade. When you’re dealing with a sweat drenched baselayer, it does not take much of a breeze to become cold.
Here’s what I've discovered:
Baselayer: merino’s ‘warm when wet’ does not work for me; as much as I love wearing merino, it soaks up more, retains more, dries much slower than synthetic, and on a multi-day trip becomes unnecessarily heavy; a soaking wet baselayer can add pounds. I only wear a thin merino short sleeve if it is a summer trip with lots of sun where I know I can dry it out on a rock in an hour or two, like in the Sierras. I’ve gone back to thin synthetics. They stink, they don’t feel as nice, but they dry faster, especially under insulation. As much as I’d like to keep my clothing weight low low low, I’ve learned that I need to bring an extra dry baselayer, even something silkweight. At night, I’ll put that on, then my wet baselayer. then my insulation. That usually does a fair job of drying out my shirt for the next day.
Rainwear: Sadly, I’ve come to realize that all the progress in breathable materials does not apply to me. I’ve spent more than a few years chasing breathable waterproof jackets, but when you sweat a lot, it just won’t make a difference. None. Only one thing will: pit zips. (And for bottoms, I use a zpacks kilt)
Insulation on the move: After years of trying varied materials and layering combinations, I have found one piece of clothing that has become invaluable, allowing me to remain comfortable in my sweaty skin: Patagonia R2 jacket. On hikes that keep me in the shade or cooler altitudes, in shoulder seasons and winter, this jacket has served me well. I abandoned fleece about the time the Patagonia Nano came out, concentrating on the ‘lightest’ clothing. But I finally came back around to my beloved R2. Under it I wear a thin synthetic, short or long sleeve, depending on temps. I always have a windshell within reach for when I stop (I use an Arc Squamish because it’s a perfect fit over the R2). I prefer the R2 jacket over an R1 hoody because I can regulate better with a full zipper, however, in the winter, I’ll wear an R1 hoody under the jacket. In camp, I'll throw a synthetic or down jacket over the R2.
As a sweaty person, I’ve come to accept several things that will never change:
I will always have to deal with wet clammy skin despite the season.
Anything marketed as breathable or moisture wicking, even if it is legit, will not apply to me.
And finally, I will always have a heavier base weight than I’d like because being someone who sweats a lot requires different considerations than someone who doesn’t.
Hope that helps.
