SIDE NOTE: Wool vs Fleece (or Wool vs Synthetics)
There has been a bit of resurgence in the use of wool for backcountry use (esp in base layers). So what to use? It honestly does not matter for most people; it comes down to personal preference. As long as you do not use cotton, you should be fine. Many people use a combo of wool and synthetics (esp in winter). If you are curious of the pros and cons of each, here is my personal take:
Wool
- Warm when damp
- Can be inexpensive (thrift stores, surplus) or expensive (Smartwool, Ibex, etc)
- Tends to breathe better than synthetics
- More durable
- Less odor
- Takes longer to dry when wet (and becomes heavier)
- Usually bulkier and heavier than comparable synthetics or fleece
Synthetics or Fleece
- Dries quicker (but is not warm when damp)
- For base layers, good ole' polypro can be ridiculously cheap
- Usually less heavy and bulky than the wool equivalent
- Can get a pungent odor
So what do I use?
For winter use, when I am more concerned about warmth than weight (and I am wearing most of my layers), I tend to favor wool base layers (except for the liner socks) as it is more forgiving of sweating I find. A wool hat tends to be warmer if it gets damp in snow vs a fleece hat as well. A surplus wool sweater is now my warm layer of choice, too. In the cold, dry conditions of Colorado, I find wool works very well overall.
In three season backpacking, when weight and bulk is a chief a concern (and most of my layers are stowed), I tend to wear synthetics. Any moisture in spring through fall tends to be rain (or very wet snow), so the quick drying properties of synthetics comes in handy.
Overall, you may find one combo works better than another based on your budget, availability of what you may already have or just personal preference.