Alpha Direct (no shell) vs traditional/regulator fleece?

Hans,

Alpha Direct insulation averages a specified .38 clo/oz. The closest fleece option is Polartec Thermal Pro High Loft at .210 clo/oz. Classic fleece (100,200, & 300) have a clo oz of .143 clo/oz. Base layers such as the Patagonia R1 or Capilene Thermal Weight have lower clo/oz than other fleeces because they are engineered primarily to be liquid moisture movers versus pure insulation pieces.

I tested the US Special Forces L3A (Polartec Alpha) jacket as having the exact same insulation value as their L3 fleece (Polartec Thermal Pro High Loft). Although the Alpha insulation had a higher clo/oz, the addition of two layers of fabric to protect it yielded the same insulation value clo/oz. The naked Alpha variant under a shell shouldn’t experience the fabric weight penalty.

It is important to note that fleece or Polartec Alpha are excellent “Active” insulations and are not competitive with the clo/oz of “Static” insulations like 800 FP down, Primaloft Gold, etc. for clo/oz.

It is also important to note that a backpacker will generate 4 times the heat when “Active” versus doing camp chores (Static). Most UL backpackers find the lightest weight fleece insulation layer (Polartec 100) adequate under a shell down to below freezing.

The US Special Forces are provided “Active” insulation guidelines to only wear their L1 and L2 base layers alone or in combination, under a shell, to 0F and then add their L3 Polartec Thermal Pro insulation for temps to -20F.

I wouldn’t mind trying this in combination with an Arcteryx Squamish hooded windshell for winter activities like cross country skiing, ice climbing, etc.

Thank you very much for the detailed information Richard – that’s precisely what I needed.

Of course, stating that Polartec Alpha is probably an overkill for active use as I might end up too warm (i.e. a simple R1 would be sufficient). And for static use, there are better options such as down.

I will experiment a bit and see where the line between static and active will end up for me.

In find the clo/oz values interesting.

Maybe my memory is fuzzy, but when Alpha was first released in garments where it was sewn with an outer shell fabric, naysayers on here said it was no different than regular fleece coupled with a wind shirt, and was therefore marketing fluff.

Comparing the clo/oz values for Alpha, Thermal Pro Hi-Loft, and Classic Fleece that Richard quotes above would suggest otherwise.

Maybe you are purely looking for a layering option, though you said you would wear this with a wind or rain shell…

Anyway, the Rab piece seems odd. It weighs 10 oz. That is only 1 oz less than the very functional Patagonia Nano Air Light hoody which does have face fabrics and is super comfy, quite warm, and still breathable. You can wear it with our without a shell. The Alpha Direct stuff is like wearing a mesh shirt that has some dandelion fluff stuck to it; absolutely zero wind resistance. I tried a Norrona Alpha Raw hoody and thought the bare Alpha was pretty weird stuff. Maybe I needed to give it more of a chance, but I just couldn’t get past the crazy loose weave. It was like Angora crochet done by a beginner with fat fingers. But as Richard points out it has the highest clo/oz, so if it is going under a shell, maybe that’s the best option. It just seems like a functionally limiting option.

Philip, that’s the whole point of this thread – comparing the naked fabrics and their CLO – not apples and oranges.

I’m not interested in softshell jackets if I can achieve the same thing with a more versatile 2 piece combination. That’s the opposite of functionally limiting if you ask me :)

I imagine another benefit of alpha direct would be faster drying times due to the open weave and option to wear without a shell. Can anyone confirm this in comparison to a piece like the Nano Air Light? Also wonder if it would be warmer when wet than a nano air light because of the ability to keep water off the skin without the inner fabric.

Polartec Alpha was designed for the military so that it could get wet and be faster drying than traditional fleece.

It would be interesting to see a side by side comparison of  a couple different Alpha pieces vs Patagonia’s Nano Air Light.  One would think that a piece like the Rab Alpha Flash would dry extremely quickly compared to the Nano Air Light, which has both a shell fabric and a liner fabric.  Outdoor Research’s Ascendant Hoody, one would assume, would fall somewhere in between.

I actually had a “last season closeout” Ascendant on my “To Buy” list for this winter, but now I think I’d rather get the Rab item.  More versatility.  Combine with the Squamish to have the functional equivalent of the Ascendant, wear it alone for more breathability and faster drying.

Am I missing anything?  I believe BLN’s review of the Nano Air Light felt that it was somewhat greater than the sum of its parts, particularly when it comes to fit and the softer feel of the fabrics that Patagonia used, with the downside being shell durability.

I suspect the Nano Air would dry faster since it’s a less dense insulation. The inner and outer fabrics are lightweight poly which dries quickly too.

I had both to compare them, the Rab Alpha Flash and Nano Air/Light Hoodies. There are a couple of threads related to this topic, e.g.: https://backpackinglight.com/forums/topic/polartec-alpha/

Note, there, Richard doesn’t recommend Alpha Active Insulation to backpackers, but if I remember correctly there were not too many options without a shell available at that point.

Another issue is the warmth, it’s probably way too warm for normal backpacking – although I’m not sure if there are different weights available (again naked) by now.

From my point of view it doesn’t make any sense to directly compare these options. The nano air is like a naked alpha jacket with a fixed windshirt on it.

I use the Alpha Flash mainly for winter ski touring in the Alps at night. Although it is very warm, due to the very loose fabric there is a lot of air circulation. If I’m static I just add a windshirt and it’s very warm.
I also sometimes use it if I’m less active and expect wet weather (snow/cold rain) instead of down or a different fleece.

Comparing it to the Nano Air variants is pretty straight forward: The Nano Airs are convenient. You don’t have to bring a wind shirt, it looks much better, etc. But since the shell is fixed, it won’t dry as fast and you don’t have the versatility of a separate windshirt (or rain shell, or whatever).
It’s a typical softshell. I liked to wear it in everyday scenarios, biking, etc – it feels and looks nice, great climate – if the conditions are right.
I consider the combination of a naked alpha jacket + shell more technical. The durability is much much lower as the fabric is not protected and quite “fuzzy”, but you can’t beat the versatility with these (endless) possibilities to combine layers.

Richard, a followup question – is there any table where you have collected these values? This is quite interesting – I didn’t have the exact numbers before.

I often find myself forgetting where each fleece ends up and have to search through the forum reminding me how alpha compares to regulator, capilene, primaloft etc.

I know there are various tables such as:
https://backpackinglight.com/forums/topic/polartec-alpha/#post-3439423
https://dpcr19kltm61a.cloudfront.net/backpackinglight/user_uploads/1235191188_10421.jpg

But they seem to be missing some of the information you posted earlier…
A combined resource online would be very convenient – I notice the same questions about these numbers popping up frequently in the forum as well.