primaloft gold is one of several water-resisting down insulation versions currently out there, and is probably the most stable.
most WP down has been nano-treated to reduce being compromised by moisture but the jury is still out on how well that will last. already early versions have been withdrawn or not remade as a question mark hangs over durability and cost. remember Patagonia’s show-stopping WP down effort..?
Primaloft, in an effort to both keep their relevance as a synthetic insulation provider and to resolve a potential problem, has gone with combining their existing synthetic insulation with down, sometimes WP as well, and theyve done it intelligently. Primaloft synthetic always has been a decent water-repelling fiber, so placing it on the outside of the down is already a good start, with different grades (gold, silver & black) having different weights. just as smart is the way that Primaloft synthetic comes in a sheet, so it forms a total layer, bridging the sewn-thru areas and forming a good resolution for the cold spots normal sewn-thru down garments have. another element to this is that sewn-thru is cheaper than full-baffles, so helps off-set some cost whilst giving a decent solution.
usage -wise the synthetic layer helps act as a windproofing, and perhaps most vitally it gives the down a bonding surface to sit against which reduces it shifting about inside the baffle, both features adding up to make Primaloft Gold reliable for belay jacket applications.
the synthetic element, aside from being a protective layer (which means a more breathable shell fabric can be used too) and plugging much of the heat loss thru the stitching, give the down a degree of integrity that lets it dry faster when it does wet out. over the long term too – the how and when of the WP nano-treatment on the down – the synthetic element means regardless of what happens to the down you still end up with a jacket that copes with moisture much better than normal down alone, meaning a $450 jacket doesnt potentially become a $300 jacket due to some hazy process.
by the way; anyone else ever wondered why down isnt naturally waterproof? it seems to be for geese, ducks, swans etc…..