Base Layer Tops

Reviewed by Jake W

The Fjallraven Bergtagen Woolmesh Sweater is a base layer top that utilizes wool in three different weaves to maximize heat retention in key areas (chest, back) and breathability in others (stomach, underarms). It’s a total home run of execution and since I received this top for testing I have worn nothing else. It’s exceptionally well tailored, durable, doesn’t stink on multi-day trips, and you’ll have no fear around a fire. The only possible negatives are more inherent to wool, than this product—it takes longer to dry.

PREAMBLE Fjallraven is right up there with Arc'teryx in the confusing naming scheme of their products. The Woolmesh Sweater is part of their Bergtagen line (Bergtagen is a Swedish word used to describe the feeling of being captivated and humbled by the mountains, awesome name), which includes the base layer (two top options and two bottom options, both men's and women's), mid-layer insulation (two different jackets for both men and women as well as an elephant style sleeping bag), outer shell (pants and jacket, both men's and women's), and a work layer (pants and jacket, both men's and women's).

Read more: Fjallraven Bergtagen Woolmesh Sweater review (1)

Featured review by David Link

A super-comfortable and versatile Merino blend hooded shirt, excels as a sun or wind shirt. This is the first time I’ve really tried a long-sleeved sun protective shirt, and I was pleasantly surprised how comfortable it is in warm conditions. Though it is marketed as a sun shirt, it is much more than that.

  Morning walk in the foothills Having read several super positive reviews about this hoodie, I wanted to give it a try, but was put-off a little bit by the price tag. But having recently moved to the Sierra foothills, where it is generally colder than the central valley, I went for it anyway, and was not disappointed.  Fit and Comfort: I would consider the fit to be on the "athletic" side. I wasn’t quite sure whether to order the XL or the XXL. While I usually fit XL in most shirts, occasionally they can be a little tight (Icebreaker shirts are a good example of this.

Read more: Voormi River Run Hoodie reviews (2)

Reviewed by BigRed

Black Diamond's Solution 150 Merino Base Crew is a lightweight, polyester-reinforced merino wool base layer. Cool enough to wear under light shell clothing for high intensity activity at around-freezing temperatures without overheating, but easily layered over for use in colder conditions or at lower intensity. Stretch fabric gives a comfortable fit even on a slim frame and dries a little faster than 100 percent merino.

(Preliminary review based on the first month of use) Black Diamond’s Solution 150 Base shirts and long underwear are lightweight, polyester-reinforced merino wool base layers. They are light enough to wear under light shell clothing for high intensity activity at around-freezing temperatures without overheating, but easily layered over for use in colder conditions or at lower intensity. BD has supplied me with both a crew neck top and ¾ length bottoms for testing. Much of what I have to say about the one will apply to the other and so may be duplicated in both reviews.

Read more: Black Diamond Solution 150 Merino Base Crew review (1)

Reviewed by OutdoorKelly

The Kari Traa Rose Longsleeve is a 100 percent merino base layer that is comfortable, warm, and durable. It's thin enough to layer without restricting movement, and incorporates a range of colors and sizes to appeal to a variety of adventurous ladies! Just be prepared to size up as this base layer runs SMALL!

Testing Conditions: I tested the Kari Traa Rose Longsleeve from December 2018 to December 2019 as a member of the Trailspace Review Corps. Testing conditions ranged from -25 to 20 degrees Fahrenheit in the following activities: hiking, fat biking, snowshoeing, backcountry skiing, alpine (resort) skiing, and nordic skiing.                                                                  Rose Longsleeve front view Fit & Comfort: For those who aren't familiar with Kari Traa, the Norwegian brand was developed by its namesake, a female Olympian freestyle skier. The Rose Longsleeve is a base layer made of 100 percent merino wool.

Read more: Kari Traa Rose Long Sleeve review (1)

Reviewed by Jake W

The Smartwool Merino 150 Pocket Tee is an active wear, base layer made up of 87% merino wool and 13% polyester. The high wool content maximizes one of nature's greatest insulator's ability to regulate temperature, ward off the multi-day stink, and manage moisture, while the polyester content adds durability and comfort. A lightweight wool tee allows for an endless amount of uses—from a thin sun shirt on hot summer days, to an excellent next to skin layer as part of a clothing system in winter. I've worn this from the trail, to the crag, to the pub, to the lake, to chasing the kids around the yard; it is really just that versatile. The fit is a little baggier than I would like, but that one constructive criticism is more than offset by the comfort, function, and versatility of this tee.

  First off, a disclaimer—I am an unabashed wool fan. It's amazing to me that man has made so many "revolutionary" fabrics designed to do, well...exactly what wool does. Mother Nature has shown us the exact fibre to be using for years. Our ancestors knew it, most experts that make a living outdoors know it, walk through the Scottish Highlands/Canadian North/Siberia, and see what their clothes are made off- natural materials.  Wool is, by nature, "scratchy" to some people. It has come a long way from the ragg wool of past, and high quality, low micron wool, like the kind used in this tee, are a lot softer.

Read more: Smartwool Merino 150 Pocket Tee review (1)

Featured review by Lester M

An all-time classic design. Form meets function.

Every competing manufacturer has tried to persuade the public that the original HH vest is outmoded. It has no zips, pockets, or gimmicks, it isn't made of a new wonder material or rediscovered 'smart' wool. The look is like something from an '80s magazine. So why do they still get made—and sold all over the world—in large quantities? Warmth and wicking. The Lifa polypropylene meets both criteria, when your body is working near maximum and the weather is uncooperative. I even have an old white, long sleeved vest, which is perfect under a hot Spanish or Californian sun.

Read more: Helly Hansen HH LIFA Stripe Crew reviews (2)

Featured review by Andrew F.

A relatively loose, very stretchy, and ridiculously breathable base layer. Due to the loose weave, wind runs almost literally right through it. This is a combination wool/synthetic layer that provides great warmth (under a shell or in still air) and wicks moisture well. Durability...well, be careful with it. Good for a wide range of temperatures and conditions.

THE BASICS A couple of years ago, Patagonia started selling a line of base layers it called "merino air." The fabric was a very stretchy combination of 51% merino wool and 49% synthetic Capilene, which is Patagonia's outstanding synthetic wicking base layer material. I picked up a pair of the Merino Air Bottoms and have enjoyed wearing them. Then, for no particular reason, Patagonia stopped selling it.   Last year, the knitted fabric returned, reincarnated as Capilene Air. Same knitted (Patagonia says "exploded") merino/capilene blend, same qualities as the last go-around.  As you will read as I run through how this performs, it is a unique kind of base layer, easily the most interesting and useful wool blend layer I have used.

Read more: Patagonia Capilene Air Crew reviews (2)

Reviewed by LoneStranger

The Smartwool Intraknit Merino 250 Thermal Quarter Zip brings 100% Merino wool in a comfortable and warm weave. This shirt works as a base, mid, outer and only layer depending on conditions, activity and the wearer's temperament. Versatile enough to handle a wide variety of cold weather activities.

Smartwool takes a technical leap forward with their newly designed Intraknit Merino 250 Thermal 1/4 Zip and I've had the pleasure of extensively testing it over the last four months. Along with their Intraknit Merino 250 Thermal Bottom, I've pretty much lived in this shirt over the Winter. Definitely enough testing to give you a comprehensive look at this versatile cold weather shirt along with my thoughts on the subject too. Before we dig into the review I thought it might be useful to go over a few basics about wool.

Read more: Smartwool Intraknit Merino 250 Thermal 1/4 Zip review (1)

Featured review by East_stingray

I urge all review-readers: as always, shop around. I saw this top for as much as $80, but with a few Google searches found it for $30 on clearance.Unlike the previous reviewer, I found the sizing chart to provide a good fit (I'm a small). I've been favorably impressed with this shirt. I did expect it to provide a bit more warmth, however. To give a better idea, I'm a hot person in general and frequently hike with this as my shirt in 60ish degree weather with a 28lb pack with no problems. I would roast alive if I tried that with a long-sleeved shirt with any kind of insulation.

Read more: Smartwool Lightweight Zip T reviews (4)

Reviewed by KiwiKlimber

The Outdoor Research Alpine Onset Crew is a comfortable baselayer that blends merino wool with nylon and spandex to form a highly flexible, non-restrictive baselayer. It's best used for active pursuits in moderately cold temps, like hiking in chilly weather.

Conditions and Temperatures:I tested the Alpine Onset Crew baselayer top along with its bottom counterpart, the OR Alpine Onset Bottoms. These items are a part of Outdoor Research's Alpine Onset collection, which includes an array of men's and women's layers. As soon as the OR Alpine Onset Crew top arrived on my doorstep in the dead of winter, I put the baselayer on and have worn it pretty consistently since. I wore it every week for about three months, multiple days per week at times, and then sporadically as the temperatures rose for an additional two months.   I’ve worn this crew top baselayer for three months through the fields and forests of central Pennsylvania while hiking, camping, hunting, mountain biking, and for general everyday...

Read more: Outdoor Research Alpine Onset Crew review (1)