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Wool Baselayers vs Synthetic Baselayers: How to Choose

Wool vs Synthetic Baselayers. Which is Better?

Wool vs synthetic baselayers: which is better? Wool baselayer garments feel warmer than synthetic baselayers, but synthetic baselayers dry more quickly than wool. What are the pros and cons of each and which should you buy for winter hiking, snowshoeing, or skiing?

The Role of a Baselayer

When dressing for vigorous winter activities, it’s best to use a layered clothing system consisting of a wicking baselayer that moves perspiration away from your skin, an insulating mid-layer that absorbs the perspiration but still holds in your body heat, and a waterproof/windproof shell layer that keeps external moisture or wind from cooling you.

Read The Science of Clothing Layers for Winter Hiking for an in-depth explanation of evaporative cooling, wicking, and capillary action and how it can inform your choice of baselayers. 

The purpose of a baselayer top is to move perspiration generated while you’re active away from your skin so it won’t chill you. A good baselayer should have a close fit so it can effectively capture moisture, without any seams to chafe or irritate your skin. It takes extra energy to maintain your warmth if your skin is damp or wet, which is why you want a layering system that moves perspiration to your midlayer and out of contact with your skin. There the moisture can evaporate naturally without chilling you like a damp baselayer.

Synthetic Baselayers

If you sweat a lot when you’re active, go with a synthetic baselayer like Helly Hansen’s LIFA Striped Crew or REI’s Active Pursuits Long Sleeve Jersey which both have a fast-drying porous weave designed to rapidly transport perspiration from your skin up to your mid-layer.

This is critical. You don’t want wet or damp skin in winter, even if it’s buried under other layers of clothing because it will literally suck body heat out of you in an effort to dry itself. That’s how perspiration works. The body expels sweat and then tries to boil it off in order to cool itself. Instead, wicking baselayers move that sweat up to a midlayer garment that’s not in contact with your skin, so your skin stays dry while preventing you from being chilled.

While thin synthetic tops are not as insulating as wool, they’re quite durable and affordable, and you can wash and dry them a gazillion times without any special care. I have synthetic baselayers that have lasted 10+ years of constant use, while I’m lucky if I can get 2 years from ones made with wool, before they hole and disintegrate.

Wool Baselayers

If you run cold in winter and find yourself alternating between high activity and low activity levels (like downhill skiing), try might try a wool baselayer since it will feel warmer against your skin. Merino Wool baselayers are the softest, and we recommend the Minus33 Ticonderoga Lightweight Crew or the Smartwool Merino Classic Baselayer if you need a bit more warmth. However, we’d encourage you to stick with a thin wool baselayer rather than a midweight or heavy-weight one because it will wick better than a thicker baselayer garment, which just traps more moisture closer to your skin. If you still need more warmth, bulk up your midlayer insulation.

Synthetic Baselayer and Wool Midlayer

Can’t decide? Many people buy both wool and synthetic baselayers and switch between them depending on the activity and outside temperature. Others mix and match, going with a wicking synthetic baselayer and a wool mid-layer that doesn’t have to stay dry because its function is to stay warm when it absorbs perspiration passed to it from your baselayer. Personally, I prefer using a synthetic baselayer and a synthetic midlayer, since the latter can dry while I’m wearing it, as long as I take my shell jacket off and it’s exposed to the air.

Nuyarn wraps polyester around merino wool.
Nuyarn wraps polyester around merino wool to create a more durable fabric with the best properties of both.

Wool and Synthetic Blends

Still another option is to look at garments that blend wool and synthetic yarns. For instance, I had good luck with the Artilect Boulder 125 Crew which blends wool and synthetic materials to create a hybrid form of Merino wool, called Nuyarn, that is comfortable to wear and odor-resistant while being easier to care for and more durable than wool.

Which do you prefer? Wool or Synthetic?

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  1. Merino wool doesn’t stink. I’ve been on some hikes where I wished everyone was wearing it.

    • 20 years ago alot of the synthetic stuff was polypropylene. aka poly-PEW!.
      The newer stuff seems to do better but it can hold odor even after a wash especially if it was left to ferment in a laundry basket or backpack for a few days, then the odor comes back with a vengeance with a little heat and sweat.
      a little ammonia in the washing machine will remove the stink.

      • Patagonia Capilene Air (synthetic/merino knit blend) + Patagonia Nano Air mid layer + GoreTex shell works quite well for me.

    • I can make merino wool stink in just a few hours. You’re just not sweating enough.

      • I switched to merino wool quite a while ago. It keeps me warmer in cold weather, and doesn’t overheat me in warm. When I wore heavy weight werino Ulfrotte baselayers on a 20 degree morning it was toasty warm. The weather warmed to 50 and I was the only one who didn’t have to strip down and take off layers. Truly amazing stuff. I really prefer Merino to synthetic base layers and socks.

  2. I sweat alot. winter or summer when I hike, I sweat so everything i own is synthetic except for stuff I use when I’m not moving like my sleeping bag and puffy jacket (both down). my hiking pace is such that if I’m not sweating a little I speed up. In the winter I wear a synthetic base layer from Burgeon and a thin syn mid layer and I set my pace so that I stay warm like that.

  3. I like Polartec’s PowerWool wool-synthetic blend. I’ve got a quarter-zip baselayer that has become my go-to for winter hiking, cold weather biking, and international plane travel. Self-regulates great, even when walking off a cold plane onto a hot tarmac, and will take days of travel without smelling.

  4. When you run cold, only wool is warm enough! I wear -33 (brand) merino wool base layers, top and bottom. From early November to mid-April I wear a wool sweater as a mid layer. For deep snow I prefer insulated snowshoe pants; otherwise, I wear Johnson (Vt.) woolen pants over my base. I heat up the most when breaking trail, but hardly ever sweat to the point of wetness. Trails are too muddy to hike in the spring, so my synthetics don’t see the light of day until it’s hot and buggy.

  5. My go-to winter layering is synthetic base and wool midlayer on top and I will do either synthetic or wool base on the bottom. My collarbone and underarms tend to be a bit sensitive to wool so while I’m okay being a tad itchy while sitting in my office, I worry that this would cause a lot of discomfort were I out for hours exercising in a wool baselayer. My legs don’t tend to have this problem so I can do wool long underwear.

    That said, I’ve been told and have also noticed that if I’m wearing wool and it’s itchy, that’s because it’s too warm for that wool and once I am in a situation where the wool is necessary it isn’t itchy anymore, so it’s possible that a wool base would work for me on very cold days but I’m not willing to risk it. I don’t like being itchy. :-) It’s one thing if I have a hat I can take off when I get warm, but I am not likely to want to strip off an itchy shirt.

    • I am a wool grower, a professional sheep shearer, and a hand spinner. Wool causes skin irritation for those with allergies. For most of us, the itch results from the “prickle factor” and varies among breeds of sheep and also among individuals. Merino is a breed of sheep, and select merino wool can be worn by infants next to their skin. Commercial woolen wear comes through global industrial processes, so the term, “Merino,” on the label at the store cannot guarantee the quality of fiber from a well bred, healthy merino sheep. It might not even be merino. I love a wool mid layer, but I select the wool and make my socks and sweaters.

  6. Consider me lazy and I don’t want to deal with the extra needs of Wool (special washing/drying) for what might be marginal benefits over synthetics in some situations.

    Winter I wear a long sleeve REI Active Pursuits with a lightweight mid-layer. In most situations down to 15-20 degrees that’s enough to keep me warm so long as I’m moving. If I stop it’s time to throw on the puffy or a wind layer. On the bottom stick with just the soft-shell pants – though I do pack a pair of synthetic base layer as an emergency item.

    For myself heat management is mostly done at the head and hands.

  7. From a cost, convenience and odor perspective I’ve mostly moved to synthetic/merino blends for my base layer. I should add that the climate I recreate in is not overly cold but often wet (west coast of Canada). The outer shell is determined by time of year. As for mid layers, whatever the conditions demand and I don’t discriminate against any of them as they all can be the best choice for that particular day. I will add that one of the measures I used in the past was to run clothing through the washing machine spin cycle and then put it on. If it wasn’t comfortable to wear in the comfort of my home wet it wasn’t likely I’d enjoy it on the trail.

  8. On NuYarn Merino,: Kuiu uses NuYarn but markets it under the ULTRA Merino name. Pricey, but what isn’t these days :(

  9. Norwegian company Brynje and their Super Thermo mesh netting base layers (polypropylene) has been with me for all types of hikes and skiing adventures. It is ideal close to the skin wether it is in cold or wet conditions. When in high activity the mesh unique construction has few contact points on the skin, thus increasing air circulation whilst steam and excess heat is transmitted away. During low activity the mesh keeps the warm air as an isolation layer close to the skin. The items I bought (some 10 years ago) have been extremely durable, with almost no smell and is ideal for someone like me who cannot use regular wool due to itching. They are as new even today. I am in not affiliated with Brynje, this is only my subjective observation.

  10. I use Terramar’s thermawool quarter zip top, which is a very comfy polyester against the skin, with a wool/poly blend on the outer layer. It’s super light and has been perfect for ski tours in the Dacks.

  11. I tend to be on the hot side (one of my wife’s nicknames for me is HHBL – hunka hunka burning love), but I hate being wet. Unfortunately, wool tends to make me itchy against my skin – despite much effort to get used to it. I typically do a synthetic base layer (mostly EMS techwick, but I’d use capiline if I could afford it), and a merino mid layer. For me, pitzips are probably the most important part of ventilation. I let my 15 year old wear my shell during a recent rainy November trip up Flume Slide to Mt. Liberty and used his brother’s functional but non-ventilated shell and it was too toasty.

  12. In the past I have tended to use synthetics; largely as cheaper and last along time. Now I use wool most often; largely as it is usually far less harmful to the environment, in both production and use. Washing many synthetics is bad for receiving waters, although some expensive ones less so, and you can also wash them in special bags that restrict the amount of micro fibers that wash away . Some companies like Patagonia thankfully are moving away from cheaper synthetics and are using recycled synthetics which helps a lot. Still use some synthetics, but much less. Frankly, wool T shirts shirts feel so better to me but a heavy synthetic fleece can be warm and far less expensive. Still try to prioritize wool when I can.

  13. I have polyester fleece lined thermal underwear that I wear every day: to the store, to bed, shoveling snow, and on the trail. I have Marino Wool thermals and one wool blend that itches but I found that if I wear it as a mid layer it doesn’t itch. lately I found a fleece 3/4 zip top with a pocket zip parallel to it on walmart’s website. it’s a knockoff of Eddie Bauer’s same 3X the price! I loved the first one in a rose color so I bought a second one in a teal color. I wear them as a mid layer. The sleeves are nice and long. But my favorite is my Iguana Marino Wool thermals that fit like a glove, don’t smell, and are a pretty aqua color.They feel like silk. I don’t sweat much unless I’m shoveling snow and it’s deep. Then I wear the thermals and bib ski pants which are extremely insulated. I also bought a Sherpa lined “track suit” on Amazon (there’s a story that goes with that but I’ll save it for another time.) I’ve worn it twice in the house but it makes me too warm and walking in it makes me feel like Gumby. So to answer your question, I have no preference. I love them all
    My only gripe is that it takes me another half hour to put on all this stuff before I can get out the door! P.S. As for washing, I don’t do anything special for the Marino Wool. They go in the cold wash like everything else and get divided by color: darks, whites, pinks, and greens. I use All Sensitive Skin or any Sensitive Skin detergent AND Borax. I’ve never had an odor problem after washing any of my clothes. Sometimes I’ll skip the Borox if I run out and pour some vinegar in the rinse cycle instead.

  14. I have polyesters, wool blends, Marino Wools, and I love them all. I wash them together but separate them by color. I use Sensitive Skin detergents and Borax and if I run out of Borax I use vinegar in the rinse water. I’ve never had a problem with odor after washing but if that’s a problem, it could be mold growing in the washer and a wash with Lysol without any clothes could do the trick.

  15. I wear Merino socks every day and have for years. I won’t go back to cotton or synthetics now. I always wore synthetic base and mid layers due to cost and durability. I recently decided to try Merino on a whim (found some on clearance). I love it. It works well for me. If I was a millionaire, I would wear it from head to toe, but for now I will wear it this year and hope it lasts a while. Life is short and I am old.

  16. I have a question about using Alpaca LS shirt and Alpaca Fleece Hoodie as layers. I have never tried this fiber before. Specifically Appalachian Gear Company is who I was exploring. Does anyone have any experiences with these they want to share? Positive? Negative? I am starting AT in 3 weeks and was interested if these were good options.

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