Arms of Andes 160g Alpaca Base Layer Review

Why This Thin Shirt Surprised Me in Real Cold Weather

Most base layers need movement to feel warm. You hike, your body heats up, and the fabric starts to do its job. The Arms of Andes 160g lightweight alpaca base layer was different. The first time I pulled it on in my house, before I ever stepped outside, I felt warmth almost immediately. That alone made me stop and pay attention.

I have worn a lot of base layers over the years. Merino wool. Synthetics. Mesh systems. I know what “warm for the weight” usually feels like. This alpaca shirt did not feel bulky or plush, yet it delivered warmth faster than I expected, and that theme continued through real hunts and long hours standing still in cold Pennsylvania wind.

Quick Verdict

The Arms of Andes 160g alpaca base layer is a thin but extremely effective cold-weather base layer that delivers instant warmth, excellent odor control, and strong thermal regulation during long static sits. It wears noticeably thinner than same-weight merino but feels warmer in real use, especially when layered with other alpaca pieces.

Moisture management is good, not mesh-level, but it continues to insulate even when damp, which is where alpaca separates itself from most base layers. If your hunting involves cold temperatures, limited movement, and long periods of sitting, this is a high-value alternative to merino that punches well above its weight.

How I Tested It and Why This Matters

This review is based on real use, not a single wear or a controlled indoor test. I wore the 160g alpaca base layer during three cold-weather hunts this season, as well as a long outdoor ceremony where standing still was unavoidable.

Temperatures ranged from the low 20s into the mid-30s. Conditions included wind in the 10 to 15 mph range, open terrain, and long static periods where poor base layers usually reveal their weaknesses quickly. I also layered it with the Arms of Andes 300g alpaca midweight and tested it alongside insulated pieces like the First Lite Core and Thermic, which gave me a clear sense of how it fit into a full cold-weather system.

Fit, Cut, and How It Layers

I wore a size Large. I am 5 foot 8″ and 190 pounds, with an athletic build. The fit was athletic without being restrictive. It sat close to the body the way a base layer should, but never felt tight or compressive.

Sleeve length was excellent, which matters more than people think once you start layering. The torso length was also solid. The shirt never rode up while hiking, sitting, or reaching. The collar was comfortable and not tight around the neck.

One thing worth noting is that the shirt does not include thumb loops or sleeve cutouts. Some hunters prefer those features, especially when layering under fleece or insulation. In my use, the sleeves stayed in place and layered cleanly, so I did not find this to be a problem.

The Itch Question and First Wear Comfort

I did notice slight itchiness when I first put the shirt on. That needs to be said honestly. It was noticeable, but mild. What surprised me was how quickly that sensation faded once my body started warming up. When layered under the 300g alpaca, it was essentially a non-issue.

What stood out more than the itch was how fast the warmth came on. That initial warmth made the minor itch easy to ignore, and once I was outside and moving, it was no longer something I thought about. Toward the end of the day, right before taking it off, I noticed it again briefly, but it never reached a point where I wanted to remove the shirt or change layers.

For most hunters, especially those layering properly, this will be manageable. If you have extremely sensitive skin and cannot tolerate any itch at all, it is something to consider. For me, the performance outweighed that minor drawback.

Standing Still in Real Cold and Wind

One of the best tests for any base layer is standing still. Movement can hide problems. Static cold exposes them fast.

I wore the 160g alpaca base layer to a Wreaths Across America ceremony at Fort Indiantown Gap National Cemetery in Pennsylvania. The temperature was around 27 degrees, and the wind was cutting across open ground at roughly 10 to 15 mph. I layered the 160g alpaca under the 300g alpaca, with a Kuiu flannel shirt jacket on top. That was my entire upper-body system.

I stood through a 30-minute ceremony and then spent several hours afterward during wreath laying. Many people around me were clearly cold and shivering. I was not. My feet were cold by the end of the day, but my upper body remained comfortable the entire time.

That experience alone told me this layering system, and this base layer in particular, was doing something right.

Hunting Performance and Thermal Regulation

On hunts, the 160g alpaca showed a trait that is hard to find in base layers: excellent thermal regulation. It warmed quickly when I started moving, but it did not continue to trap heat once I settled into a sit. That balance is difficult to achieve.

During active periods, it felt warmer than my 120g merino base layers and noticeably warmer than mesh. When I stopped moving, especially when layered with the 300g alpaca, it maintained warmth without creating that damp, chilled feeling that can creep in with some synthetics.

This is where alpaca shines. Even when I sweated on one hunt and the fabric stayed damp longer than mesh or lighter merino, it continued to keep me warm. That ability to insulate while wet is real, and I noticed it clearly in the field.

Moisture Handling Compared to Other Systems

This is not a mesh base layer. It does not dump moisture as aggressively. If I know I am going to be highly active for long periods, mesh still wins.

That said, the 160g alpaca moved moisture off my skin and into my mid layer effectively. It took longer to dry than mesh and slightly longer than lightweight merino, but the difference was that it never made me feel cold while damp.

For cold weather hunting, especially when activity levels vary, that matters more than raw dry time.

Alpaca vs. Merino Wool

When compared directly to merino wool base layers of similar weight, the 160g alpaca behaves differently in a way that matters for cold-weather hunters. Merino tends to feel softer next to skin and dries a bit faster after heavy exertion, but it also relies more on loft and fabric thickness to generate warmth.

The alpaca base layer wears noticeably thinner at the same weight, yet feels warmer in static conditions and continues to insulate even when damp. In real use, the alpaca regulated temperature better during long sits and wind exposure, while merino shines more during higher activity and frequent temperature swings.

If merino is the better all-around, do-everything option, alpaca is the more efficient choice for cold, slow hunts where warmth retention and odor control matter more than fast dry times.

Odor Control Over Multiple Wears

Odor control was excellent. After multiple hunts and long hours of wear, I did not notice lingering smell when putting the shirt back on. That alone puts it in the same class as merino wool and far above most synthetics.

I had heard alpaca was good in this area. In my experience so far, it lived up to that reputation. Whether it is better than merino would require more side-by-side testing, but it is at least equal, which is impressive.

Thickness Versus Warmth

Both the 160g and 300g alpaca layers are thinner than you expect if you are used to merino of the same weight. That can be misleading at first. You pick it up and think it will not be warm enough.

In use, that assumption disappears quickly. Alpaca fibers are simply more efficient. Same weight, less bulk, more warmth.

Layering alpaca with alpaca amplifies that effect. The thermal regulation when stacking these pieces is excellent, especially for static cold weather hunting.

Where This Base Layer Fits Best

This is not an early season, high-output base layer. It excels in cold weather, static sits, and mixed movement hunts where you need warmth without overheating.

I would choose it over merino in colder conditions, especially when layering heavier mid layers. I would still use mesh next to skin for very active hunts, but I would happily wear the 160g alpaca over mesh in extreme cold. That combination would be outstanding.

Final Verdict

The most surprising thing about the Arms of Andes 160g alpaca base layer was how warm it felt the instant I put it on for the first time. That first impression carried through real hunts, long static sits, wind exposure, and cold conditions where base layers usually show their limits.

It is thin, effective, odor resistant, and regulates heat better than most base layers I have tested. When layered correctly, it punches far above what its weight and thickness suggest.

This is a legitimate cold-weather base layer that earned a place in my system.