Polartec Alpha: The Best Kept Secret In The Outdoors
We explain how Polartec's super versatile Alpha insulation technology keeps you cool at the same time as it keeps you warm.
It's taken almost two years for the penny to drop with us, but it finally has: Polartec's Alpha technology, launched with the line 'New Territory for Puffy Insulation' isn't actually 'puffy insulation' at all.
Sure, it might look like puffy insulation. We guess it might smell like puffy insulation, though we haven't actually tried. It might even taste like puffy insulation. And no, we haven't tried that either. But as soon as we started to use Rab's brilliant new Alpha Direct Jacket we knew it was something else entirely.
Why does that matter? Okay, here's the thing, when you think of puffy insulation, you automatically associate it with stuff you throw on purely to stay warm and comfortable when you're stopped. As soon as you move, you take it off because, well, it's no longer comfortable. It's too warm and too sweaty.
Alpha is the opposite of that, it's stuff you throw on to keep you warm while you're moving. But what's even better, is that within reason, it still keeps you comfortable and warm when you stop. It's kind of like traditional insulation but backwards.
Polartec Alpha - What It Does And How It Works
What makes Polartec Alpha different is that not only is it warm, trapping air heated by your body in cold conditions and holding it there so you lose minimal heat, it's designed specifically to keep you warm and dry rather than warm and damp.
'Because Alpha dries faster and handles moisture better, you and your baselayers stay drier. Which means that both on the move and when you stop, you simply feel drier, warmer and more comfortable. Less of that clammy chill that we're all familiar with.'
That matters for several reasons. One is that dry air is a better insulator than moist air. Damp air and damp fabrics simply lose heat to the outside world faster than dry air and dry fabrics.
Bonus fact: it's the reason, if you're interested, that damp, cold Scottish winters often feel significantly cooler than higher, drier mountains that are notionally at a lower temperature.
The other is that as you move, your body churns out a moist, sweaty fug. With conventional insulation, two layers of windproof fabric trap that damp air and hold it near to your body. The result is that you chill down fast as soon as you stop moving and your body generates less heat.
Alpha, in our experience, doesn't do that. Because it dries faster and handles moisture better, you and your baselayers stay drier. Which means that both on the move and when you stop, you simply feel drier, warmer and more comfortable. Less of that clammy chilly, shivery feeling that sadly we're all familiar with.
How Polartec Alpha Works
Haha, that's a military secret and we can't tell you. If we did we'd have to kill you. Er, just joking, though in fact Alpha was developed in conjunction with US special forces, who wanted - as you've probably worked out by now - an insulation that was comfortable on the move and when they stopped and then when they started moving again.
Check out the video below for some more, slightly American, insights:
How Does Alpha Work?
In the beginning, Alpha came as a sandwich with an inner and outer fabric, but the new Alpha Direct version does away with the inner fabric and, at the same time, makes the whole technology easier to understand.
In a lot of ways, it's very similar to the old pile and Pertex combination beloved of various ancient, gnarly old climbers in the 1980s. The principles are pretty similar: an insulating inner layer that traps air and disperses moisture and a wind-resistant outer layer that wards off wind and light rain.
The Trouble With Pile / Pertex...
The trouble with pile / Pertex combos were that they were simply too warm for most people and most conditions. And the outer totally windproof layer wasn't very breathable, so they retained rather too much of that heat as well. Oh, and they tended to be both bulky and pig ugly too.
Alpha solves both those problems. First, the fluffy inner layer is thinner than pile, so it's not as ridiculously warm or bulky. It's also technically more advanced and lighter. Second, the outer layer, in the case of the Rab Alpha Direct, is a more breathable form of Pertex called Microlight, which allows moist air to escape more easily.
The result is a system that warm, but not too warm when you're on the move, so there's no build up of moist, damp fug inside. And, because it's drier, it still keeps you warm when you do stop for a break to eat. Or to construct an elaborate belay. Or just so you can sit for ten minutes and gawp at the view, like this...
Polartec Alpha In The Real World
So what does that mean in the real outdoors? We found it works a bit like this: you set off in the morning wearing your Alpha Direct over a high-wicking baselayer. The fluffy liner feels, warm, furry and slightly luxurious. Great in the pre-dawn chill.
As you start to warm up, you still feel comfortable. And then you hit the first hard climb, gravity kicks in, your winter pack feels heavy, you work harder, you sweat a little. Your brow is moist. But Alpha works well enough that you never get that horrible, hot, damp, build-up of steam inside your jacket.
And then, as you crest the lip of a hanging cam - or coire or corrie, you decide - your feckless mate comes to a steaming, panting halt. He or she, if it's a bitch, needs a five-minute breather, a bowl of water and some doggy treats.
It's breezy and cool, but Alpha's wind-resistant outer shell keeps you comfortable, the hood protects your sensitive ears and you're dry enough that you don't need any additional layers to keep you comfortable.
'When you start off again, you just flip the hood off and motor on up. A bit later it starts to drizzle a little. No problem again. The Alpha copes nicely, you just carry on.'
When you start off again, you just flip the hood off and motor on up. A bit later it starts to drizzle a little. No problem again. The Alpha copes nicely, you just carry on.
When the rain does get worse though, much worse, you sling on a lightweight waterproof shell and because Alpha is so breathable, it works very like a fleece as a mid layer.
Snow? You just rely on Alpha, it loves the stuff. Wind? Not a problem. You get the idea. It's not quite magic, it can't defy the laws of physics, so if you stop for longer, you'll still need an additional warm insulation layer to throw over the top. And if it really rains, you'll need that waterproof.
But later, as you sit in the car driving home with a contented doggy snoring coming from the back seat, chances are that you'll still be wearing your Alpha Direct and you'll still feel dry and comfortable.
So There You Go...
Hmmm, so it maybe is a little like magic. Not too warm when you're on the move, not too cool and damp and clammy when you're stopped. The stuff has been our most-used 'mid come shell' layer so far this winter and we don't see that stopping any time soon.
Is it insulation? Is it soft shell? Is it insulated soft shell? Or mutant fleece? Or a platypus-like crossover combination of all of them? You know what, we don't know and we don't really care. All that really matters is that it works. And it works brilliantly.
Who's Using Polartec Alpha This Winter?
Here in the UK, the main brands using Alpha are Rab, Montane and Mountain Equipment, all with slightly different takes on the technology.
Rab Alpha Direct Jacket - £180
Rab's Alpha Direct uses a stripped-down version of Polartec Alpha with the original inner liner fabric removed, so the core Alpha fibre layer is exposed. As a bonus, it has a luxurious, soft, fluffy feel to it, though the exterior Pertex Microlight fabric adds plenty of wind and water resistance and a handy hood adds versatility.
Montane Alpha Guide Jacket - £140
Another technical mountain jacket, the Montane Alpha Guide is a more conventional take on Alpha. It has weather-resistant Pertex Microlight Stretch on the outside along with own brand DryActive Stretch on the inside. The stretch fabrics give improved mobility for climbing and there's also an under-helmet hood.
Another jacket using Alpha in its naked, unlined form, the Kineses teams it with ME's own super-lightweight windproof Helium 30 fabric and adds a lined, fully-adjustable, helmet-compatible Mountain HC hood for technical mountaineering use. Wear as a shell or mid-layer and when you don't need it, pack it down into its own hand-pocket and clip it to your harness using the loop provided.
More Geek Fodder
If you want to know more about Polartec Alpha technology see: polartec.com/product/polartec-alpha