I have been looking at some higher-end insulated jackets for the occasion where my heavy mid-layer fleece, heavy base-layer, and shell still would leave me cold. While I want to stay warm, I still generate a significant amount of body heat and sweat while skiing, so I need something that will move all that moisture out & I don’t get cold. While doing research, I came across materials such as Toray’s 3DeFX+ (Aka Fullrange), Primaloft Gold (AKA Primaloft One), Thinsulate™ Platinum Insulation Flex, and Polartec Alpha. I started reading about CFMs and breathability of some of these newer materials, going over stories of how the military would complain for accumulated moisture while using previous materials, and began to wonder, what is the breathability rating of the insulation inside of the shell material of the jacket I was considering? I was a little floored when I read that Polatec Alpha, on of the supposedly most breathable insulators had a breathability of 3,349 g H2O / 24 h which was almost twice as breathable as the leading competitor! This was a much lower rating than most shells out there. I wondered which insulation, if any, would be as breathable, when subjected to the steamy conditions aforementioned, as a 20k, much less 30 or 40k shell material (such as Dermizax NX). Perhaps I am interpreting the specs, but they seem pretty clear to me.
If the insulating material was not as breathable, why invest in a more breathable shell? Would a more breathable shell help the insulating material in impeding the moisture buildup, and if so, would that impact of moisture buildup be significant? Probably not. This also applies to my mid-layer, and I guess, to an extent, base layer. If they are not more breathable than 20, 30 or 40k, then why buy a shell that is that breathable? I always thought that fleeces, all synthetic insulation, and base-layers would be more breathable than a shell, but perhaps I am wrong. Please share your thoughts and educate me if you may have some insight on this subject; it would be greatly appreciated. If you know sources of where to get the breathability (CFM, or air permeability) ratings please let me know.