Brynje Super Thermo Shirt w/ Shoulder Inlay Review

Overview

The Brynje Super Thermo Shirt is a fishnet-style base layer built from Schoeller Polycolon mesh, designed for cold-weather activity where you’re alternating between hard efforts and standing around freezing your butt off. It’s been a staple of Norwegian outdoor gear and polar expedition kit for decades, and this particular version adds solid-knit shoulder inlays so a pack’s hip belt and shoulder straps aren’t riding directly on open mesh. It’s aimed at backpackers, ski tourers, and hunters who run hot on the move but need to hold heat the second they stop.

Key Specs

Spec	Detail
Weight	143 g (size M)
Material	100% Schoeller® Polycolon® synthetic yarn
Construction	3/8” open-weave mesh (fishnet)
Fit	Unisex, slim fit, long cut
Neckline	Crew neck
Sleeves	Long raglan sleeves
Seams	Flatlock
Special feature	Solid-knit shoulder inlays for pack comfort

Performance

The whole point of a mesh base layer is that it inverts how you think about layering. Instead of a snug-to-skin fabric wicking moisture away, the open weave means almost none of the fabric actually touches your skin — sweat gets passed straight through to whatever mid-layer you’ve got on top, while a layer of trapped air sits against your body doing the insulating. Reviewers consistently describe this as a “thermostat” effect: at low activity the netting holds warm air against the skin, and it counteracts cold bridging by forming a continuous air layer, so the double effect keeps body temperature under control.

In practice, that translates to genuinely less fiddling with zippers and layers. One long-time user on Backpacking Light put it simply: using a Brynje t-shirt for winter hiking, they were never too hot or too cold, and it made layering less fiddly since they didn’t need to adjust as much to avoid excessive sweat or getting too cold. Another BPL poster running similar gear while snowshoeing in the 20s Fahrenheit found the base layers performed very well, so much so they had to unzip their shell and puffy for ventilation when grunting uphill.

The moisture handling is the real party trick. Because there’s so little fabric surface area, sweat doesn’t pool and wick the way it does in a traditional base layer — it gets shuttled straight to your mid-layer. SectionHiker’s review describes this directly: the mesh traps warm air when worn under a mid-layer just like other base layers, but doesn’t hold onto perspiration because there’s less fabric to absorb it — instead it passes along to the mid-layer, keeping skin warm and dry while making the mid-layer noticeably damp, which is a very noticeable effect. That’s a real mental shift if you’re used to snug merino or synthetic base layers — you’ll feel dry against your skin even as your fleece or softshell gets visibly damp. It takes some getting used to, but once you trust it, it works.

Where it doesn’t shine is in stagnant, humid, low-airflow conditions. GearJunkie’s extended, multi-season test nailed this trade-off: they found the Brynje layers incredibly versatile across temperature ranges when there was a breeze, but they stumbled in more stagnant, hot, and humid conditions like treadmill training or fully-zipped downpour hikes — still, from single-digit hikes to 70-degree bike rides, they were among the most flexible base layers tested. So this isn’t a layer for muggy, low-wind slogs — it wants either cold air or movement (ideally both) to do its job.

On durability and odor, the synthetic polycolon version holds up well and doesn’t get as ripe as you’d expect from something worn directly against skin for days. One Trek-Lite forum user summed up years of use bluntly: the Brynje base layer did a much better job than merino, Polartec, and other technical tops they owned, and they felt warm while running and not nearly as cold as usual when stopped.

The shoulder inlay is a smart, practical addition if you’re wearing this under a loaded pack — solid knit panels mean the hip belt and shoulder straps aren’t grinding against open netting all day, which matters more than you’d think on a multi-day carry. Sizing runs true for most people, though it’s worth noting Brynje’s cuts vary between styles — one SectionHiker commenter found the zip-neck version fit true to size on a lean 6’1”, 150 lb frame, so check Brynje’s specific size chart for this shirt rather than assuming.

Pros & Cons

Pros:

• Genuinely reduces layer-fiddling on cold, active days — you sweat less into the base layer itself
• Dries fast and doesn’t hold odor like solid merino or synthetic layers
• Shoulder inlays are a thoughtful, functional upgrade for pack-wearers
• Long raglan-sleeve, slim cut layers cleanly under a shell or mid-layer
• Decades of use in Nordic and polar expedition contexts back up the core concept

Cons:

• Underperforms in humid, low-airflow, or fully-sealed-shell conditions
• Looks like fishnet underwear — fine once it’s hidden under a mid-layer, less fine if anyone sees you putting it on
• Best benefits show up specifically in cold/cool, active-then-static use — less of a slam dunk for warm-weather or continuous steady-state hiking
• Premium pricing for what is, materially, an open-weave synthetic shirt

Who Should Buy This

This is for people who run hot climbing and get cold fast the moment they stop — ski tourers, winter backpackers, hunters sitting in a stand, or anyone doing start-stop cold-weather activity where traditional base layers leave you either soaked or chilled. If most of your hiking happens in mild, humid, or low-wind conditions, the core advantage of this shirt is largely wasted on you.

Verdict

The Brynje Super Thermo Shirt earns its cult following in cold-weather, high-output activities — it’s one of the few base layers that actually changes how much you need to fuss with your layering system on the move. The shoulder inlay is a genuine practical improvement for pack-wearers, not just a marketing bullet point. I’d rate it an 8.3/10: excellent at what it’s designed for, but skip it if your trips run warm, humid, or low on airflow.