/ The enigma that is Polartec Alpha
The only advantage to primaloft one I can see is that it allows manufacturers to use more 'breathable' fabrics on the jacket.
Many alpha jackets have a mesh back which I can see would increase breathability by a long way over conventional fabrics.
Alpha is less warm than primaloft one, so the only reason to buy alpha would be its claimed increase in breathability.
I thing that the 'controlling resistance' to breathability of a synthetic fabrics must be the outer and inner fabrics. The breathability difference between primaloft and alpha (only the actual insulation) is very small compared to the outer fabric.
Therefore the only advantage of alpha over primaloft is the ability to use more breathable outer/inner fabrics. Marmot have used pertex quantum in their isotherm jacket, therefore it has virtually the same breathability as a primaloft garment with the same outer fabrics.
My second point is about the 'air permeable' nature of synthetic insulation outer fabrics. Synthetic insulation works by trapping a warm layer of air close to your body. With alpha's supposed intended use of more air permeable fabrics, surely the wind will rob you of warm air you have trapped, therefore rendering your insulation somewhat useless!
I can see the point that polartec is trying to make, however I don't think the science behind it backs their claims up.
IMHO, the only thing an alpha jacket does a slightly better job compared to a primaloft one, is as a midlayer due to it's increased breathability beacuse of the mesh inner fabric.
N.B. I have no affiliation with Primaloft or any grudges against Polartec. I'm just a consumer who has done a little bit of research into the area and would like to get the highest performance synthetic jacket for his money!
Please prove me wrong :)
Two layers of Pertex is presumably less breathable than one, though.
That is exactly the point I'm getting at. The only advantage of alpha I can see is the ability of a jacket manufacturer to use one outer pertex layer and a mesh layer instead of an inner pertex and outer pertex layer in a primaloft jacket.
I basically agree with you. These fabrics are not yet used quite right. They've been around for ages (google 3d-spacer fabric) but never took off because the design of the jackets were always a bit mad. Polartec have 'done an Apple' and reinvented them. Google Spinktex for one early example.
To make best use of them I think they should be lined with mesh and the outer fabric should be something like Pertex. However, the outer fabric should have loads of zips/openings, allowing you to vent at will. A Buffalo design in spacer fabric would be awesome.
This may well be true but do you know it for certain?
Alpha is knitted into sheets so that it doesn't need to be held in channels like down. I think Primaloft also has to be held in place somehow too - hence jacket design needs to be a bit more complex/heavy.
My review of Alpha and the Marmot Isotherm in particular: http://lightfromthenorth.blogspot.fi/2014/02/marmot-isotherm-hoodypolartec-alpha.html
Do you think it would be better to think of it as a warmer, lighter and more compressible replacement to fleece?
I've used several of the obvious primaloft jackets over the last few years, and since December also the rab strata with the alpha fabric. The main thing I've noticed is that is far less sweaty than primaloft. I suspect this is partly because it's less insulating so I'm not actually getting as hot, but I still think there is some element of increased breathability.
It's definitely a good fleece replacement if it's really cold. If it's really cold and dry, I've also used it as a soft shell just over a base layer.
I think you have to ask yourself what you are hoping to use it for. If it's as a useful all year layer, then an alpha might fit the bill. If you need weather resistance and warmth for belaying, maybe primaloft.
Agreed. Most of the folks I know who have Alpha jackets think they are better for moving in. But if you are not moving, then I think primaloft insulates better. So Alpha for a winter piece you'll be wearing on the go and primaloft for a summer alpine belay jacket.
I reckon that is still far more a function of the fabrics the jacket is lined and faced with than the insulation itself.
Even with its different structural design to normal Primaloft and all those holes to help it breath better?
Surely they or someone have done tests to show it breathes better rather than it just being a case of different shell materials making the difference?
Totally anecdotely it feels very different to me, I wear mine as a mid-layer or light outer softshell and it feels much better than even a light primaloft top.
I think there is a bit of confusion surrounding Alpha and Primaloft.
Blackreaver got it right, tops using Alpha are more of a fleece replacement and they do seem to breath/wick better than Primaloft. It would appear that this is because of the inner mesh type lining and the structure of Alpha. Primaloft tends to consist of interwoven strands, which trap heat better but possibly slows down the movement of moisture. Alpha only has strands running from inner fabric to outer fabric (simplified and possibly not entirely accurate description;). This helps move liquid away from skin quicker and does not trap as much moist warm air. Of course it is not as warm as Primaloft...but it's not supposed to be. It's an active insulation as opposed to static insulation.
Every one I've spoken to, thinks it's bloody fantastic. Used in Iceland doing Sprengisandur route (not myself) and wide variety of U.K. winter conditions.
I think Alpha clothing is ideal cold weather active insulation, much better than light Primaloft clothing. The weather resistance so far, newish Strata hoody,is awesome. Functions well as an outer or inner layer.
Really curious to see what the brands do with it. I think it's potentially game changer if used in well designed garments. I should mention I work in the retail side of the Outdoor industry, no affiliation to any manufacturer.
But that's a function of whatever fabric Rab have made the jacket shell from, not the Alpha. You could make a Neoshell jacket lined with Alpha (I think some brand actually is IIRC) and that would be very weather resistant.
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