Introduction
There are three types of wool clothing used by backpackers.
They are wool, wool blends and “wool themed” clothing.
In addition there are wool alternatives.
Why wool?
There are good reasons and bad reasons and “other” reasons for wool.
The bad reasons is that “wool is warm when wet”– it really isn’t that much warmer than anything else.
The good reason is that it is odor-resistant, absorbs less moisture (in lighter weights) and wears well. Merino wool is also comfortable, without the “wool itch” that older and other types of wool are likely to have.
Quoting experts
I generally prefer merino wool because it’s far more odor-resistant and it’s warmer when wet (though not “warm”). But I can make an argument for polyester, too: it’s much less expensive and more durable, absorbs less moisture and dries faster, and can be milled in lighter weights, which makes it cooler and a better moisture manager than the lightest wool fabrics. Also, in dry environments I find that polyester is much less offensive smelling, especially with a backcountry wash every two or three days
https://andrewskurka.com/backpacking-clothing-go-suit-short-long-sleeve-shirt/
and
Short or long sleeved baselayer shirts are a good example. In this application merino wool has, in the last decade, become the fabric of reference due to its superior moisture managing properties. Merino is not inherently warmer than various synthetics when wet, despite frequent claims to the contrary, but it does manage evaporative cooling by absorbing sweat into the wool fibers and releasing them in a moderated fashion. Merino also does an excellent job of resisting odor, though given enough use between washings it is not immune to bacterial growth. The only reason, aside from cost, merino has not taken over completely is the difficulty of balancing performance and longevity. Thicker merinos (>150 grams/meter) have too much fiber and hold too much moisture too long. I’ve written them off for anything aside from casual, town use, and know exactly no one including cold-blooded light sweaters who having used sub 150 gram wool have any desire to go back. The problem with thinner merino is poor abrasion resistance, something to which Skurka aludes both in writing and in pictures. The latest and best solution is to blend polyester with the wool, two examples being Rab Meco 120 and Patagonia Merino 1, both of which are 65% merino and 35% polyester, and 120 grams per square meter (3.5 ounces per square yard). These shirts are identical in function and appearance, and blend the characteristics of modern merino and polyester fairly well. They dry fast, but not as quick as the lightest pure poly fabrics, while still having a modicum of moisture buffering. They resist stink well, but not as well as pure wool. They’re tougher than the pure wools of comparable weights, but not as durable as pure polyester.
https://bedrockandparadox.com/2015/03/21/skurkas-core-13/
So, the three types of wool
For backpackers, straight merino wool was very common 5-10 years ago. The problem with it is that it doesn’t wear as well.
That fact has been well known since the tests with adding nylon to wool socks. At 10-15% added nylon to wool, socks last longer. Since acrylic socks became prevalent, and 100% nylon socks took over dress socks, that fact was forgotten.
Then came the merino wool revolution and backpackers. It wasn’t long before wool + spandex/nylon became popular because it lasts so much better. It also has other performance advantages. As long as the wool is at 85% or more of a garment, I refer to it as a wool garment.
Then there are wool blends. Most are somewhere between 65% to 35% wool. Some of the best socks available (e.g. Darn Tough socks) are “62% Merino Wool 36% Nylon 2% Lycra Spandex”.
The Kirkland socks I’ve taken to wearing every day and hiking in are “57% Merino Wool, 40% Nylon, 3% Spandex”. (I like them enough that I use them even though I have Darn Tough socks with the life time guarantee). I like the amount of cushion they have.
Finally, there are “wool themed” items. I have some long sleeved t-shirts I wear for casual wear, that are “11% Merino Wool, 84% Polyester, 5% Spandex.” Comfortable, wash well, perform well. Not for hiking, but not bad around the house.
The bottom line is that when buying be aware that a fair amount of clothing sold as “Merino Wool” is actually just “wool themed” — which is fine when you are paying bargain prices as Costco, not so fine when it costs more than something from Woolx, Smartwool or Icebreaker.
When shopping for Merino, I advise people to get blends with 10-15% nylon and/or spandex in them so that they will wear better. Wearing holes in a t-shirt early in a hike isn’t my goal. I’ve already done that.
Wool Alternatives
Most sun hoodies are made from wool alternatives. E.g. the Crater Lake Sun Hoodie by Mountain Hardware that I now hike in is ” 88% Polyester, 12% Elastane.” The Black Diamond Alpenglo that my wife likes is “87% Polyester 13% Elastine.”
Polyethylene and polypropylene had moments. They are both very hydrophobic (so they do not absorb water but wick it well) and can be warm, but they tend to accumulate stench unless manufactured with a good deal of care.
They were very popular for warm layers and then rapidly lost favor. They are making combacks in the market as a search on Amazon will reflect.
Polyester is more breathable than nylon and costs less to manufacture. Nylon is also more hydrophiliac (water absorbing) than polyester. Polyester also resists UV light much better.
There are proprietary blends of polyester, such as Capiline (disclaimer, my baselayer pants that I’m currently hiking with are capilene) and Polartec Silkweight which is used by the military for base layers (disclaimer, I own a set of Polartec silkweight as well, if I wasn’t carrying a baselayer as a hedge against cold weather, I’d be hiking with it instead).
Keep in mind that in World War I everyone wore wool pants. You won’t see a backpacker in them. Wool is obviously not the best for everything. Instead most hikers are in “convertible pants.” Also note that those pants are most likely going to be Nylon/Spandex. Watch out for blends that include cotton as you don’t want that as a wool alternative.
Bottom Line
Not too long ago, I replaced all my casual wear with heavy weight premium cotton.
Of course I started backpacking right after I made that change. Now I wear a blend of Merino wool and synthetics when hiking and when backpacking.
Much of the downside to synthetics, especially polyester, have been mitigated by improved technology. Still, for many uses, blended merino wool remains the best choice.
Which brand of merino wool do I recommend? Whatever is currently on sale. The best price/performance seems to vary week to week. Sometimes it is on Amazon, sometimes at the manufacturer’s website. Eventually 32 Degrees will be selling Merino and then they will be the best and least expensive.
32 Degrees just isn’t selling merino wool yet. Be aware that sometimes the high end products don’t fit as well or have other defects (currently looking at you Patagonia Capiline Sun Hoody without thumb loops and with a hood that flops about and wind blows right off my hat). Off brands are usually off brands for a reason, but sometimes you can find quality.
I remain unapologetically a bargain hunter. Brand name shopping isn’t always a panacea. Nothing beats looking at gear yourself and comparing when you can, especially as industry products change and evolve.
Finally, be wary of “best” and “recommended” lists. Often what they really are is attempts to get you to click on and buy from an affiliated marketing link. In merino wool products, “Best” changes too often and your body shape is probably not the same as the reviewer’s body shape.
