Podcast Episode May 31, 2024

Episode 102 | Polartec Alpha Direct

Episode Sponsor

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Today’s episode of the Backpacking Light Podcast is sponsored by Garage Grown Gear, your hub for all things ultralight. Garage Grown Gear is dedicated to supporting the growth of small, startup, and cottage brands. Today, we are featuring innovative products from those brands made with Polartec Alpha Direct, the lightest, most breathable, and most air-permeable fleece insulation available.

Polartec Alpha at Garage Grown Gear

Discover the comprehensive selection of Polartec Alpha Direct hoodies, shirts, pants, socks, hats, and more from small, startup, and cottage brands.

See it at Garage Grown Gear



In today’s episode of the Backpacking Light podcast you’re going to learn about the origin, evolution, and use of Polartec Alpha Direct in modern ultralight layering systems.

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In this Episode:

Featured Brands and Products

Farpointe Alpha Cruiser at Garage Grown Gear

An Alpha Direct hoody is an ultralight way to carry fleece that's more comfortable and breathable than a traditional fleece.

WEIGHT: 4.0 to 4.9 oz (113 to 139 g)
  • available in both 60g and 90g weights
  • very high air permeability for fleece
  • when worn under a shell, very high warmth-to-weight ratio
  • not as durable as grid fleece or pile
See it at Garage Grown Gear See it at Farpointe Outdoor Gear
Arcteryx Squamish Hoody Mens
WEIGHT: 5 oz (140 g)
MVTR: 3420 g/m2/hr
APR: 29 CFM/ft2
  • Rare combination of adjustable ventilation, high MVTR, high APR.
  • Expensive.
  • High APR may not be the best option for low-exertion activity in high winds.
See it at Arc'teryx See it at REI

Note: Alpha Direct is commonly available in 60 gsm (grams per square meter), 90 gsm, and 120 gsm weights. Lighter weights are suitable for 3-season active insulating layers for hiking in cool conditions, or as pajama layers. Heavier weights are best used for inactive insulation (e.g., in camp) or during the winter. Alpha Direct is used in torso and pant layers, caps, and socks. Because of durability limitations, Alpha Direct socks should be relegated for sleeping and in-camp use only.

Polartec Alpha at Garage Grown Gear

Discover the comprehensive selection of Polartec Alpha Direct hoodies, shirts, pants, socks, hats, and more from small, startup, and cottage brands.

See it at Garage Grown Gear

Main Topic: Polartec Alpha Direct

  • US Military’s PCU (protective combat uniform) and how it relates to outdoor clothing layering systems – lightweight undergarments, midweight undergarment, fleece, wind jacket, soft shell jacket and pants, wet weather jacket and pants, extreme cold weather parka and pants
  • Comparing Polartec Alpha fabric (required to be stitched to unbreathable shell fabrics) with Polartec Alpha Direct (does not require to be stitched to unbreathable shell fabrics)
  • The Polartec Alpha Direct as a multifunctional layering piece – as a warm insulated outer layer, as a base layer, as a warm insulated layer within a storm system, insulated layer within a breathable windshirt system

Links, Mentions, and Related Content

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Home Forums Episode 102 | Polartec Alpha Direct

Viewing 22 posts - 1 through 22 (of 22 total)
  • Author
  • #3812622
    Backpacking Light


    Locale: Rocky Mountains

    Companion forum thread to: Episode 102 | Polartec Alpha Direct

    In episode 102 of the Backpacking Light podcast you’re going to learn about the origin, evolution, and use of Polartec Alpha Direct in modern ultralight layering systems.

    Ryan Jordan


    Locale: Central Rockies

    I didn’t get to mention this in the podcast, but this winter I did experiment with a Mark Twight-style layering system with Alpha Direct in windy, cold weather:

    • Brynje long sleeve fishnet mesh base layer
    • Wind shirt (usually an Arc’teryx Squamish)
    • Polartec Alpha Direct fleece hoodie
    • WPB Rain Jacket

    I liked it, it was comfortable and nimble. I just started to try this towards the end of winter, but was curious to know if others had any experience with this type of system (fleece between the wind shirt and rain shell layer) using AD.

    Mole J
    BPL Member


    Locale: UK

    I wear my windshirt under my fleece layer on some occasions.
    It adds another dimension to layering (cooler than Windshirt over fleece) And also enables the fleece layer to slide over the windshirt and give more freedom of movement. The latter is definitely welcome when wearing a waterproof layer as well as it can feel less restrictive when scrambling in more technical terrain.

    It’s funny though because I’ll sometimes get companions saying “what are you doing? That’s pointless, you’re wearing it the wrong way around!”. You can lead a horse to water …


    I use a Polartec Alpha 90 hoody for all my backpacking for the last few years. It’s open and often windy in the UK. Just the Alpha fleece and a windshirt is quite a comfortable combination in a lot of instances.

    Also, another instance of versatile layering, is wearing my baselayer (Rab Pulse Tee usually) over my Alpha hoody rather than under it.

    It pays to experiment and be flexible.

    Terran Terran
    BPL Member


    I wear a base layer over the alpha. (Brynje) I’ll sometimes wear a very breathable R3 over that. While it doesn’t totally block wind, I believe by combining the different fabrics, there is no direct path. The wind doesn’t bounce off my skin, taking my heat. IDK. I do find it very comfortable under certain conditions. If it’s too windy, I might wear a tech face R1 instead. It all sheds water to some degree. Next or instead, I may wear a very light Pertex Shield shell (Luke’s), or perhaps a DAS (pertex shield) hoody.
    As Mole said, “it pays to experiment and be flexible”. What I actually carry depends on the weather reports.

    BPL Member


    Locale: The West is (still) the Best

    I use a Polartec Alpha 90 hoody for all my backpacking .. Just the Alpha fleece and a windshirt is quite a comfortable combination in a lot of instances.

    Alpha-direct works at about half the weight for cold-sunny to cold-rainy conditions for a small trade off (90gsm) in durability.   Also for brief camp stops.

    Still I layer a windshell over the alpha garment as the latter is more susceptible to get snagged, etc..

    BPL Member


    Locale: Northern California

    Yeah I’m the horse  who  doesn’t drink that water. Or maybe the mule…a windshirt over fleece or an R1 or  whatever layers you have blocks wind–hence,  the name–and provides protection from moisture. Meanwhile, the inner layer(s) is maintaining warmth and expelling moisture that the windshirt ideally allows to wick away. wind carries off warmth. cold  wind carries off even more warmth. I wear a layer to retain warmth. Synthetics are pervious to wind. A windshirt blocks wind. How is this backwards?

    BPL Member


    Locale: Northern California

    …I find fleece to allow wind and make me cold.  A rain shell or a Houdini–a windshirt–blocks wind.

    [edited – MK]

    Matthew / BPL


    Acknowledging I did a little editing above to keep things on track.

    Also, I’m a little bit confused about layering a windshirt under fleece too. Generally speaking, my understanding of AD is that it is a very breathable fleece which gives the user the ability to enjoy that breathability or to limit it with another garment over the top.

    RJ suggests, essentially, that one could layer under and over an AD layer. I suppose that makes sense to me. It’s almost like making a jacket with a breathable but wind resistant inner, AD insulation in the middle, and a WPB exterior. Now that I have typed that out, I don’t have trouble accepting that this would be warmer than the fishnet baselayer + AD + WPB shell.

    I can accept that if one was going to wear all four layers that the layering order can matter: fishnet + windshirt + AD + WPB sounds warmer than fishnet + AD + windshirt + WPB. In the latter version the outermost two layers seem redundant.

    Monte Masterson
    BPL Member


    Locale: Southern Indiana

    One of the main attractions of Alpha Direct over the original Alpha is the fact it can go “directly” against the skin (or thin base layer) without the need for an inner shell. Might as well just buy the much cheaper Alpha if you’re going to place a breathable nylon/poly layer underneath. Simplicity is a big appeal to Alpha Direct and making things complex with 4 layers seems to negate any small (possible) thermal gains. Kind of like an overengineered machine with way more unnecessary components than are needed. https://discoveryfabrics.com/products/polartec-alpha-insulation?variant=39934359994453

    Matthew / BPL


    Yes agreed it seems to work well directly against skin.

    I don’t think this is Ryan’s intention but it is certainly plausible that I would have all four of these layers present and that I would get cold and start putting everything on at once. Before I read this I would have probably gone base layer then AD then windshirt then rain shell. I don’t think the windshirt does much directly under the shell. Somehow I can see Ryan’s layering doing something more than that.

    Bill Budney
    BPL Member


    Locale: Central NYS

    My recollection of Mark Twight’s original suggestion is a little fuzzy. Wasn’t he talking about fleece in general (rather than Alpha Direct)? I also seem to recall that he was discussing a quick-change use case.

    Something like base+windshirt (which is my most-used combo), then add fleece if cold, then add hard shell if still cold. In that case, it makes sense — there is no reason to de-layer while working; just add layers to the system. It’s quicker (and warmer) than taking off the windshirt to add fleece, then putting the windshirt back on. Also, it allows the fleece to dump a little heat, which can be useful in some conditions. That works especially well with grid fleece which has less air permeability than Alpha Direct.

    I specifically did not get the idea that he was recommending it as a normal way to use fleece. It was more of a special-case thing for rapid change with minimal interruption, IIRC.

    Did I get any of that right? ;)

    As Monte points out, I use AD next to skin or, in very cold weather, over Airmesh (optionally over Brynje). I wouldn’t bother to wear AD over a windshirt, and my AD fits snugger than my windshirt anyway. Grid fleece is a different matter — that could easily go over a windshirt, or even replace a windshirt, while active in cooler temperatures.

    Terran Terran
    BPL Member


    Or AD, windshirt, mesh, WPB.


    Roger Caffin
    BPL Member


    Locale: Wollemi & Kosciusko NPs, Europe

    Our solution (Sue and me) is a light fleece, a windshirt to block the wind and walk fast. Works fine even in the snow. But when we stop, THEN the down jacket goes on. Quite fast sometimes.


    Terran Terran
    BPL Member


    Often my wind protection is my WPB. Then the idea of stripping down to my base layer to rearrange my clothing when I could simply put on a jacket isn’t that appealing. While the afore mentioned system may be more versatile in a variety of conditions, it seems rather unnecessary for singular conditions.

    Monte Masterson
    BPL Member


    Locale: Southern Indiana

    “Like” for Terran Terran’s above post. The simple solution is the best. Comes a point where making things overly complex and time consuming is more mental gymnastics than gaining any real comfort or performance.

    Chris K
    BPL Member


    To Monte’s last point, and maybe more so Roger’s, what about carrying/wearing less overall layers and accepting a fractional amount of discomfort on either end of a shift in conditions? So long as you have the safety angle covered with protection from rain and cold (per Roger), there is value, and maybe skill, in knowing you’ll be OK with these more subtle changes in temperature. The body is pretty adaptable in this way.

    I get this is an annoying position. I think about these layers every trip also.

    David D
    BPL Member


    Here’s frost build up inside my breathable-back but wind block front nordic skiing top shell after a long -25C day hike

    Frosty shell

    I’ve also tried a newer Houdini @-30C as a top shell.

    Showing this to illustrate that for me, a WPB shell just doesn’t breathe well enough for me at any temperature, it traps too much humidity from sweat.

    Now, a Dooy is perfect.   But at stops, I still need to throw on a fleece and if the wind is whipping, over layer the Houdini.

    I’m allergic to down but still don’t use my synth puffy even at stops.  I find fleece+Dooy+Houdini far more flexible and still the same or less weight.  No puffy shell fabric is as breathable as a Dooy

    Roger Caffin
    BPL Member


    Locale: Wollemi & Kosciusko NPs, Europe

    So long as you have the safety angle covered with protection from rain and cold
    This is where experience comes in, when you know your limits.

    There have been a few times when we have both been shaking with the cold but not too fussed because we knew that we could be inside the tent very soon, out of the wind, and getting changed. Yes, that was pushing the envelop a bit, but we knew we could manage.

    Although there was one time when Sue couldn’t get her wet clothing off: it was too sticky and she hadn’t the strength! That was soon fixed when I got into the tent.

    Hum – maybe going solo means you have to be a bit more conservative? Could be wise.


    Mark Ferwerda
    BPL Member


    Locale: Maryland

    BTW, the audio quality on this podcast is great. I’ve had trouble hearing past podcast using my iPhone (I have a hearing loss) but the audio on this one was loud and clear enough to easily hear what was being said while I’m doing other things. Good job Chase!

    Chris K
    BPL Member


    Good point, Roger.

    Matthew / BPL


    Yeah excellent point about being a little more conservative when going solo.

    Steve S
    BPL Member


    Jack Stephenson argued that a vapor barrier raises the skin humidity and lessens insensible perspiration. In my experience something akin to that does occur. If so, that first windshell barrier near the skin may work to lessen insensible perspiration, thereby lessening moisture buildup in outer layers in colder weather. Think puffy clothing, ready to go limp when warmed; wool, ready to be wet; and me surprised when I thought I was buying a cup of coffee at a ski area on day 4 of a winter trip above 6000′ in Montana intending to drive to a different trailhead to continue. I was not wearing a near-skin wind shirt on that trip.

Viewing 22 posts - 1 through 22 (of 22 total)
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