There have been a few threads on OM recently about synthetic mid layer and belay jackets, and they got me thinking about how good the most often mentioned type of insulation, Primaloft, really is. It's claimed to be the next best thing to down, but in my experience it isn't even in the same league. I've got a Primaloft jacket (although it's not one of the heavier belay-type ones) and vest, and while they're pretty warm, I wouldn't describe either as toasty. In fact they seem very thin and, when a strong wind "plasters" them against my body, they don't feel as if they've got any loft at all.
By contrast, an old jacket I have with a fill of Polarguard or something like that does give that impression of almost instant warmth. I'm not saying it's as warm as down ? and it weighs a fair bit and packs down to the size of a Triumph Herald ? but it does feel like a winter garment.
So, am I expecting too much from Primaloft insulation? Does it perhaps perform better in the laboratory than on the hill? Have I been unlucky with the garments I've bought? Or does it just lack the psychologically warming "fortress" factor?