Sometimes old tech is better than new tech, especially if it’s improved via the use of new(er) materials. Brynje Super Thermo Mesh is a prime example of this.
To put it simply, and quite frankly, Brynje Super Thermo Mesh baselayers are far and away my best outdoor purchase this year, and probably within the last three years. Let me first say that I’m not sponsored by Brynje, a Brynje supplier, and even paid (almost) full RRP for these bad boys. But they’ve been worth every penny! Although you probably shouldn’t wear them to go to the pub…
It’s difficult to really explain how effective these are. Let’s first start with a little fuzzy science (by that I mean I’m not going to use any quantitative information, and rely more on anecdotal evidence backed up with some sound reasoning).
In a “traditional” layering system, you aim to keep yourself comfortable by insulating yourself sufficiently from outside influences (rain, wind, etc.), whilst preventing your body from overheating and sweating too much whilst working hard, and subsequently cooling down too much when stopped or at a reduced effort.
For now, we are going to exclude the shell (which is mostly responsible for acting as a barrier), and mid layers (responsible for increasing insulation when necessary) and focus on the base layer. We can consider the base layer as a mechanism primarily responsible for insulation (usually by trapping air next to or near the skin), and for moisture management (i.e. moving sweat or errant rain away from the skin). Modern base layers are generally pretty good at the first job, whilst often fairly poor at the second.
This is because even modern technical clothing, whilst capable of drying out much more rapidly than the bane of all outdoor enthusiasts – cotton – still retains moisture within the fabric until it is able to escape from the fabric to the outside world. Until this moisture can escape, it sits in the baselayer, cooling you down when you stop, and making you feel a little uncomfortable otherwise.
Unlike solid-weave clothing, Brynje mesh really excels in both respects.
Envisage it as fishnet clothing with smallish holes. The string which makes up the fishnet creates pockets of air next to your skin. These air pockets are responsible for insulation, as long as there is an extra layer on top of the Brynje (for instance a wind shirt); it’s the same idea as a knitted woolen jumper. Conversely, if you’re too warm it’s easy to vent heat quickly just by exposing some skin (probably a bad choice of words).
At the same time there is only string in contact with, at a rough guess, 30% of your skin, and the weave is made with polypropylene which is inherently hydrophobic, reducing the amount of water it will naturally absorb. This combination of relatively low contact area and low water absorption means that very little moisture is held against your skin, even after extended periods of hard effort. Instead, moisture is moved quickly away from your body, keeping you warmer and more comfortable.
A personal favourite is to combine Brynje with a super-breathable softshell, such as Vapour-rise, which really excels at moving moisture outwards. As an example, at the end of each day on my Spine recce, the outside of my jacket would be soaking (or at least visibly very damp) but the Thermo Mesh and my skin underneath would be almost dry!
Another example comes from my recent trip to Scotland. Walking up to our camping spot for the first night we experienced some of the worst weather I have ever had the pleasure of encountering – sideways driven wet sleet anybody? – and was thoroughly miserable by the time we made camp. After pitching my tent in a short window of reasonable weather, I dove inside to get rid of my very wet outer clothes to find that my baselayer and skin really weren’t far from dry, and when morning rolled round there really wasn’t any discomfort when I put my (slightly damp) baselayers back on. In fact, they warmed back up so quickly that it made putting all my other clothes back on pretty much a non-issue. The thicker threads of the Brynje separates damp outer clothing from your skin enough that you don’t feel particularly damp and clammy, and if clement weather (or even just no precipitation) rolls round, it gets a chance to dry off.
Honestly, I could go on for hours about how good the Brynje mesh is. Basically, if you feel you can deal with the fashion faux-pas that is string underwear, get some. You won’t be disappointed.