These are not your grandfather’s long-johns.
Long underwear used mean waffle-knit white cotton. It held in
moisture, became cold and clammy, heavy and downright unpleasant. There
are few innovations as important to enjoying the outdoors as poly-pro
long underwear.
The high tech marvel: polypropylene long underwear, is light, wicks
moisture away from the skin, does not get cold and clammy and keeps one
toasty warm. When first introduced poly pro was prohibitively expensive
and hard to find. Now it is reasonably priced and commonly available.
Poly pro has afforded me perfect comfort during many outdoor days
and nights at below freezing temperatures. I carry it in all seasons . I
require that our scouts have it in their gear year round for protection
against hypothermia during inevitable cold, wet days that occasionally
surprise us.
There are many brands and types. I honestly cannot see a big
difference between the expensive and inexpensive brands. There are
different thicknesses (light, medium and heavy) I recommend lightweight
for all but the harshest conditions. Duo-fold is a reliable brand, (I
have yet to buy a brand I found unacceptable), their website is a good
place to start.
Duofold website