What is a Base Layer? Merino vs. Synthetic

Author / Justin Helvik, Avid Outdoorsman

hunter in field - merino vs. synthetic baselayers

There was a time when cotton long johns, a t-shirt, a pair of blue jeans, and a Carhart® jacket were the norm for western big game hunting. Now, however, many backcountry hunters push the limits and look for anything that gives them an edge. Today, traditional wool fabrics go up against synthetic fabrics for the title of best base layer. When one looks to push their hunt to the brink, every fiber counts. Here we examine the following factors many backcountry hunters consider to be important when it comes selecting the proper base layer.

  • Breathability / Moisture Management
  • Warmth/Temperature Regulation
  • Odor Control
  • Durability
  • Comfort

What is Base Layer Clothing?

When making a mad dash in desert heat to cut off wary prey or post holing in soggy snow while searching for sheds in the spring, you are going to want a fabric that breathes incredibly well. Despite merino base layers making leaps and bounds in recent years, synthetic fabrics have the edge when it comes to breathability and moisture management.

The Chinook Series, with Merino6™ technology, is incredibly breathable for wool fabric. However, few pieces rival the Avro Synthetic series, composed of 100 percent polyester, when it comes to high-exertion activities. It dries faster and is more breathable. Whether hitting the gym or a running ridges after bugling elk in early season, the Avro Synthetic will serve you well.

jeff with moose

What is the Warmest Base Layer?

A wool base layer has the uncanny ability to keep you warm even if you get soaked. All of the synthetic fiber technology in the world has a difficult time competing with mother nature. Wool can soak up moisture without feeling wet due to its unique fiber anatomy. This is one reason why it can still keep you warm even in the wettest conditions. Polyester, as mentioned earlier, may dry out faster compared to wool, but nature’s insulator is a clear winner when it comes to temperature regulation. The Chinook will keep you in the game no matter what the elements are.

washing baselayers

Can You Wear Underwear Under a Base Layer?

When on an extended trip, do your hunting buddy a favor and wear underwear under your base layer. The hollow fibers that make polysynthetic clothing so breathable are the same reason they allow for more microbial growth, creating stench. Synthetic fabrics in recent times, including the Avro Synthetic series, have incorporated Polygiene® (infusion of silver, an antimicrobial agent) into the textile to help combat microbe growth and stench. In my experience this does help, but eventually the odor catches up. This can vary from person to person. Wool, on the other hand, has the natural ability to keep the stench at bay for a much longer time period. If you’re on a week-long trip and sharing a camp, go with the Chinook. Your hunting buddies will thank you for it.

bear claws on tree


Wool, as a stand-alone historically does not hold up as well to the wear and tear of backcountry hunting. This is why companies use wool blends. By adding poly fibers into the wool weave, garments will typically hold up longer. However, by integrating synthetic fibers into a garment you begin to lose the properties that make wool so special. If you look closely at the makeup of many wool pieces, you will often find that they are not even composed primarily of wool. The Chinook series walks this fine line as well or better than any other wool product on the market. It is nearly 90 percent wool, yet it holds up incredibly well to the abuse of backcountry hunting.

The Avro Synthetic fabric is 100 percent polyester, resists pilling, and will outlast most any piece of clothing in your arsenal. As far as longevity and durability goes, the Avro Synthetic line is primo. 

helvik elk packout


For those with sensitive skin, wool may irritate your skin. This is another reason why apparel companies incorporate other fibers into their garments. This is also highly dependent upon the quality of merino in the fabric. Many avoid wool or wool-blend clothing due to the discomfort. The Chinook series debunks this paradigm.

Most anyone who tries on a Chinook base layer won’t realize they are wearing wool until told otherwise. The Avro Synthetic series is silky smooth and light on your skin. Both the Chinook and Avro Synthetic have seams strategically placed so they don’t irritate your skin. The anatomical fit of both are also conducive to active backpack hunting.

The Chinook and SG Synthetic feel different but are equally comfortable in their own regard. If you sweat profusely, you will feel more comfortable in the Avro Synthetic. However, if you encounter widely fluctuating temperatures, the Chinook will keep you cozy.

hunter in mountains


So, who’s got your back? The easy solution would be to buy both, but this might not be in the cards for the budget conscious consumer. It really boils down to what type of hunting you do, where you do your hunting, or what time of year you do your hunting.

If on a training hike, out on a day rip looking for sheds, or spending a day on the river, the Avro Synthetic series is clutch. If you’re going on any type of backcountry trip for an extended time, especially in unpredictable conditions, the Chinook series has extraordinary properties that make it a backcountry stalwart.

Product Use Scenario Matrix

Scenario Merino Draw Synthetic
Day Hikes/Scouting/Training X
High Exertion Activities X
Shed Hunting X
Fishing/Boating/Rafting X
Archery Trips 3 Days or Less X
Archery Extended Hunting Trips for 5+ Days X
Late Season Rifle Hunting Trips 3 Days or Less X
Late Season Rifle Hunting Trips 5+ Days X
Sun Protection/Hot Days X
Fire (campfire) Resistant X
Odor Control X
Temperature Regulation X
Breathability X
Packability X
Durability X
Renewable/Biodegradable X
Stain Resistant X
Overall Comfort X

About the Author: Justin Helvik is a high school principal, avid outdoorsman, mountaineer, and trail runner. Justin live in Bozeman, MT with his family.