Polartec Alpha?

[Richard Nisley]

Woubeir,

You asked, “which typo was fixed ?” and the answer is:

The Pertex spec for Quantum GL is less than 10 CFM. vs the prior

The Pertex spec for Quantum GL is less than 10 CFM.

[Woubeir (from Europe)]

The Pertex spec for Quantum GL is less than 10 CFM. vs the prior

The Pertex spec for Quantum GL is less than 10 CFM.

Euh ?

[Christoph Blank]

@Richard I was referring to https://backpackinglight.com/forums/topic/44347/#post-1709043 “Pertex Microlight which I tested 15.59 CFM”

[Jeff McWilliams]

@Bob I never jumped on the PCU 3A. Turned out we needed a new washing machine instead.  :-/

 

[Edward John M]

So help me get this in perspective, the Clo value of the Alpha material itself is a fixed quantity depending on the weight chosen but the wearability and full insulation value depends on the permeability of the outer shell only?

Is there a quick breathability test for fabric other than trying to suck air through it?

When sucking air what is the scale relative to CFM as a generalisation?

I can suck though my Montane Featherlite only by going red in the face, breathing through my taslan parka is hard work but I can do it and the fabric the Australian Army uses for its windshirts is somewhere in between those two

[Woubeir (from Europe)]

When sucking air what is the scale relative to CFM as a generalisation?

There is a formula but as it involves walking speed, wind speed and air permeability, it is not simple.

[Andrew S]

Why is it that fleece or naked Polartek Alpha (like the Rab Flash jacket with no inner or outer shell) combined with a wind shirt benefits from a boundary layer effect, but a Polartec Direct jacket with its own outer shell fabric does not?  I can understand why you get extra insulation from a boundary layer between two fabrics that do not allow a lot of air movement (e.g. a hard shell over a down jacket).  But if you can also get the same benefit from a shell over a fabric that does allow a lot of air movement (e.g. fleece, or Polartec Alpha, which looks like it allows similar air movement to a very loose knit sweater), why does it matter whether the shell fabric is attached at a small portion of its surface (as with Alpha direct) or not at all (as with the Rab Flash)?

Indeed, wouldn’t an Alpha direct jacket get the full “good-fit” boundary layer benefit, since the shell fabric fits perfectly?

P.S.  I know it’s an old thread, but I searched and didn’t find a better one with the same topic, so perhaps it’s better to keep the Alpha discussion in one place?

[Sean P]

@Andrew S: my impression from reading this thread is that fleece bonded to a shell layer (such as a macpac sabre – ) loses the benefit of a boundary layer and this was what was being referred to.

What you are referring to is a loose shell layer over a polartec alpha layer with an air gap in between.  It should not matter whether these two garments are separate (i.e. a Macpac Nitro and Kor Preshell)  or stitched together in a few places to make them one garment (such as a Macpac Pisa).

I would be suspicious of anyone who claims otherwise without a reference to a scientific paper stating how this could be so.

[Andrew S]

Sean P, thanks!  This makes sense to me – that a polartec alpha layer with a shell fabric over it will have the same insulation value whether or not that shell fabric is attached (in a few places to make them one garment).  The remaining question is whether that insulation value includes the same boundary effect that one gets when a shell fabric is over a fabric that significantly restricts the movement of air (e.g. the outer fabric of a down jacket) – or on the contrary, you get a smaller boundry effect (or none?) when the sell fabric is over a fabric that permits a lot of air movement, like polartec alpha.

[Eric Blumensaadt]

So what’s the advantage over say, 200 weight Polartec?

Weight? Warmth? Both?

[Sean P]

Moisture transport, warmth per gram, breathability.

Not as warm as a 2oo wt fleece, at least my hoodie isn’t.  But I never take a 200 wt fleece hiking anyway – my midlayer is the alpha or a very lightweight gridfleece.

[Brett Peugh]

I mainly use my OR Ascendent Hoody for around town and as more of a midlayer.

[Andrew S]

How it compares to 200 weight Polartec fleece depends on which Polartec Alpha.  I’ve come across 60, 95, and 120 gram versions (and others?).  Since it’s more than a little warmer per gram than the fleece, the 120g version might be warmer, or not.  I believe a post by Richard above may provide the numbers one would need to compare these two fabrics/insulations.

[Andrew S]

Might there be an additional advantage over traditional fleeces?  Promotional materials mention compressability.  Is it compressable?  And if so, how much?

(Even a very light fleece (I guess the one I’m wearing now is what is called a grid fleece) takes up a lot of space in a pack.  If alpa cuts down on that a lot, then even without any other advantages, I’d want to get some.)

[Sam Farrington]

A few years ago, the fleeces with a grid pattern inside were very popular and there were a number of threads on BPL.  I first saw these products on Patagonia, which listed weights in its product catalogs.

So I ordered and replaced my backpacking fleece tops with those made with the grids.  They were lighter as well a much more compressible, and as far as I could tell, provided the same warmth.

 

[Sean P]

The alpha scrunches up pretty small and is light and compressible enough to take purely as a sleep layer in cold conditions.  It doubles as a base or mid depending upon conditions.

 

It is like a wooly string sweater – seems to be largely air so it does compress nicely.  I can’t imagine taking a traditional fleece garment into the field now.  But, as an outer layer – where it snags on scrub,  it is not durable – so there is that.

[Michael E]

Might there be an additional advantage over traditional fleeces?

I think it depends a lot on your use cases. As this Outside Online article points out, Alpha was developed specifically for SOF because:

“They were asking for something that would have enough insulation that when they stop, they wouldn’t have to add layers, but that wouldn’t cause them to overheat immediately when they got moving again too,” says David Costello, who ran the program for Polartec that developed Alpha.”

Insulations like Alpha or Octaloft can provide that put it on keep it on ability versus a traditional fleece. That may or may not be important depending on your activities. The article mentions that they had originally tried an R2 type fleece jacket, but, “while traditional fleece proved good at providing insulation, even when wet, it just didn’t cut it once soldiers were on the move. “Feedback said they just weren’t wearing it.”

[Serge Giachetti]

I’ve been using alpha for a couple years now and I’d highly recommend it for its warmth/weight and breathability. I was using the rab alpha direct fleece (9oz, 90grams) and lately been using a senchi designs hoody (5oz, 60grams). Under treeline I usually wear them alone, and above treeline with a breathable windshirt or shell jacket in a storm. The senchi layer is really useful piece for the weight (similar to macpac nitro, but designed more like a melanzana). The 60 grams is a bit more fragile, but for 3 season use, its got the right amount of warmth and breathability to wear under a shell in a storm. Makes a world of difference in sustained rain or wind and provides a nice buffer/wicking layer to keep the baselayer dry. You can find senchi on instagram. They also sell alfa leggings.

[Andrew S]

Thanks everyone for sharing your experiences!

As for Senchi, sounded interesting. Shame they don’t have a website yet. All interest lost … .

[Edward Barton]

I have the alpha direct (90g) senchi hoody and the light 60g leggings, fantastic stuff. I love the hood which is less close fitting and with better coverage than most, and along with the lack of zipper I find it much more comfortable than say a Patagonia thermal hoody, a bit warmer too despite being lighter by a couple oz, and faster drying as well because of the open weave. And supporting a super small company is great too. I have a somewhat older version of the hoody and the pattern is not super refined but honestly I find that part of its charm. I don’t like the complicated patterns and associated extra seams in more mainstream outdoor clothing. These pieces are more comfortable I think in part because of how simple they are.

[Brett Peugh]

How much does the 90g Senchi Hoody cost?  And what might an XL weigh?  Thank you.

[Link .]

. POLARTEC ALPHA DIRECT HOODIE (CUSTOM) TIMMERMADE .

[Brett Peugh]

Nice for Custom.  I wonder if they can get the 120gsm material but probably not.  10week delay is a bit of time :)

 

[Link .]

I should have known better than to post something , I have learned my lesson

[Brett Peugh]

No, thank you, I did not know about them.

[Author]

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