Zpacks

"Would you be interested in my Valandre Mirage"

Way too heavy. It's about the same weight as what I'm using now.

Besides, a quarter-zip isn't much of a zipper.

–B.G.–

Apparently zpacks is using a cuben fiber baffle material.
Baffle Material: .34 oz/sqyd Cuben Fiber

This explains why the bags are lighter and warmer and I'm thinking a
cuben sleeping bag might be a wonderful thing as long as you know
what the tradeoffs are.

1) temperature regulation, the question
is if you do need to wear a down jacket to bed will you come out all
clammy. Cuben does not breath. The solution is to have a bag that is rated at 20 degrees if you are camping at 30 degrees or rated at zero degrees if you are camping at 15 degrees.

2)durability. I know from experience with an epiphany cuben quilt you cannot stuff cuben into a tight stuff sack without damaging the cuben. Don't worry Tim Marshall I have been babying my Epiphany K quilt.

3) Moisture retention, will the bag dry easily on the trail if need be?

Anyone with a zpacks sleeping bag know the answers?

"Cuben does not breath."

Cuben does not _breathe_, but that would be an issue for a shell material. Baffles should be oriented away from the shell material and are used simply to keep the down from shifting very much. I would not think that there is much moisture trying to move "up" the bag or "down" the bag. Moisture should only be trying to get "out."

Besides, which way is "down" in a down bag?

–B.G.–

Since the cuben is just used for the baffles, it really doesn't affect the moisture/breathing side of things like it would if the shell was cuben.

Personally 0.33oz cuben makes me a little nervous in this application. It's a cool material and I've made a couple stuff sacks out of it with good results, but with something as expensive and hard to repair as a quilt, I feel a lot better with 0.51oz cuben. 0.51oz cuben has triple the spectra, so it's far stronger stuff and you'd be hard pressed to damage/tear it. 0.34oz cuben should be fine, but if things get a bit twisted when you stuff it, or if you get a bit aggressive then I could see some stitches pulling out. Keep in mind this is just speculation on my part and not based on actual testing with cuben baffles. I'm sure with reasonable care, they're going to be fine 99% of the time…..but you're only saving ~0.1oz opting for this over 0.51oz cuben. I'm sure Joe would make you a quilt with either variant of cuben if you asked.

Dan, I thought a little about that possible issue of stitches tearing the cuben. I think it matters if the baffle seam allowances were too tight. Assuming that they are proper, then the spectra threads shouldn't get torn out. Or, at least I am hoping that.

On the other hand, just suppose that a worst case twist happens and some baffle stitching tears for a couple of inches. It's not like the end of the world. Some down might shift.

I've unshifted down before.

–B.G.–

So since the bag has vertical baffles; it should breath just fine.

I was curious about the tear strength of the baffles so I emailed Joe about it.

here is what he said:

"I tried it out. In the attached picture I am pulling as hard as I can on a simulated .34 oz/sqyd baffle sewn to SevenD. You can see the pin holes on the cuben are stretching, but it isn't tearing.

I was eventually able to tear it off after repeated tugging in diffrerent directions. The cuben tore before the SevenD.

I repeated the same test with a screen baffle and the screen tore relatively easily.

So I am not worried about it. A normal baffle would never be subjected to that much stress. Unless maybe it got tangled up in a washing machine or something like that. (Hand wash!!)."