In reply to Martin1978:
> By adding a windproof layer beneath the garment you are going to effect the breathability of your layering system
Of course you are, although I've always found things like Pertex and Marmot driclime breath plenty for me and I'm a hot, sweaty type on uphills
> and defeating the object of neoshell.
I guess only if your windproof layer isn't breathable at all.
> Also, adding an insulated shell layer underneath (or any extra layer), to combat this negative side affect of air permeable membranes, will cause you to run hotter.
Of course - adding any layers under a shell makes me sweatier if I'm going up hill.
> As I mentioned in the other thread, it's more than just feeling the wind coming through Neoshell that's the problem. It's the wind coming through a damp layer which acts like an air-conditioning unit, and is freezing cold (even when windchill alone is above freezing). The neoshell layer will always be damp as there's a constant exchange of moisture going on.
Physics suggests this is true although that doesn't take into account the warmth gains that
increased breathability should also offer. If you are wearing a less breathable jacket and sweat builds up wetting your under layers, then you will be losing heat by conduction too. Does one offset the other? Is one process more important than the other? Under what atmospheric conditions? Mr Fuller is probably the person best placed to discuss this; I suspect insulation/heat loss mechanisms on an exercising human will be very very complex with atmospheric conditions and individual physiology making things alter wildly.
> I always thought weather protection for a hardshell was wind and rain? Having used windproof layers that aren't waterproof over soaked base and mid layers I know that windproofing is vitally important to survival in the mountains.
But breathability is also important for hardshells, because if they lack this and you wet out your own base and midlayers, that also means you will lose heat rapidly. If gortex is wind protection 2, rain protection 3 and breathability 1, and neoshell is wp 1, rp 2 but breathability 3 (and of course those are completely made up values to illustrate a point) then you could say they are different approaches to offering the same level of protection?
From my experience of two different NeoShell jackets now I don't want to over-stress the air perm issue. Yes; I think it is MORE noticeable than Polartec claim, particularly under the conditions I point out. But it is not as if the material has no windproofing qualities at all. It is actually rather windproof; just not as much as Goretex*.
*Matt Fuller, IIRC, also pointed out that windproofness is a factor of they physical rigidity of the material as well. A soft light thin material (gore paclite for example) will deflect in wind and 'pump' air around inside your clothing possible causing convective heat loss. Probably lots of us have noticed that a heavyish 3 ply goretex mountain jacket with tough facing material is 'warmer' than a very light flexi paclite jacket for example.