Organic Merino Wool base- layers
Merino is excellent at regulating body temperature, especially when worn against the skin. The wool provides some warmth, without overheating. It draws moisture (sweat) away from the skin, a phenomenon known as wicking. The fabric is slightly moisture repellent as keratin fibers are hydrophobic at one end and hydrophilic at the other- nice design! This allows the user to avoid the feeling of wetness.
Like cotton, wool absorbs water (up to 1/3 its weight), but, unlike cotton, wool retains warmth when wet, thus helping wearers avoid hypothermia after strenuous workouts, eg, climbing or weather events. Like most wools, merino contains lanolin, which has antibacterial properties, I rotate my pair for 6 months and they go a long time without smelling bad. Due to finer fibers and small scales the wool is super soft. The small fibers have microscopic cortices of dead air, trapping body heat similar to the way a sleeping bag warms its occupant.
We're into some of the advancements in modern synthetics, especially high performing breathable waterproof skins, but there's nothing like organic merino wool undies and down for feeling perfectly snug in dry powdery winters.
Basically, these undies are awesome, if you live in a cold climate, get some...