I find these things as hard to write as read.
Might have confused things a bit, I havent used silk in a project but see it mentioned (for s/bags) recently here (?). Anyhow:
I was just 'considering' bonding, i though I saw where someone had successfully bonded baffles. Though, yes, washing was my concern too.
I didn't plan on any quilting, just the sewn (and or bonded) side seams.
In essence, what i'm banging on about is a summer weight sleeping bag with a waterproof base.
The daydream i'm having is a high cuben floor and mometum top for the shell, silk for the inner. I'm considering Climashield for the top insulation, down to mat level. No insulation in the floor/base, just a pad sleeve formed between the Cuben and silk.
It wouldn't act as a Vapor Barrier.
I could make a quilt but like an enclosed bag, the idea seems to offer a highly breathable bag with a waterproof base and water resistant top. I'd likely put a short zip somewhere (down the middle?) on top to open it up, perhaps a 'hatch' in the top at the foot section.
Thanks, i'll read back through your other thoughts, good stuff!