reflective coating in sleeping bags

Yeah, super old thread, but there are breathable aluminized fabrics with useful applications, for example the SOL Escape Bivvy. (very thorough review)

The SOL looks rather heavy and expensive for a VLB? Though the (modest) breathability would be nice, the warmth-for-weight looks a bit questionable.

My interest would be to boost a lightweight down bag for the odd colder passage during a long thru-hike. A Mylar bag in the bounce box would allow for a convenient if slightly uncomfortable margin of safety if the weather looked like turning chilly.

But how to use it without soaking your base layer? I’m guessing there’s probably a reason why this isn’t a widely used strategy?

UL base layers dry very quickly when you get out. When I use one I flash dry in seconds

I guess I should just try a practical experiment. Quite easy to set up cheaply…

Experiment using a big plastic bin liner. Something I keep in my rucksack at all times is a couple of the thin and light ones. My old VB shirt is now a little tight on me but using that in really cold weather allowed me to wear my down parka inside my bag with much less moisture getting into the down bag. My legs don’t sweat any where as much as my torso and head.
I have been thinking about buying the reflective HotSac VB liner from but shipping from the US is crazy at the moment and the exchange rate isn’t favourable