Quest WPB Material

A standard coated nylon works good for the bottom. I used Momentum fabric for the top.

–B.G.–

I thought Momentum was just water resistant – less resistant than silnylon even.

This is going to be a standalone shelter to use without a tarp and MLD uses silnylon bottoms on even their event bivies right? So I was thinking silnylon would be fine there.

Momentum is supposed to have a durable water resistant coating. So, it is partially water proof. Is it enough? That is a judgment call.

Back in the old days, maybe thirty years ago, I sewed my first two bivy sacks. They had a coated nylon bottom and a Goretex top. Goretex is a little bit "old school," but it works, especially in wet and cold weather. The problem is that it is a little bit heavy. (This is BPL, right?)

Go to the other extreme and use an uncoated taffeta, and it would be very light and breathable, but maybe not waterproof enough at all.

I determined that Momentum had enough waterproofness balanced with light weight and breathability for me. YMMV.

–B.G.–

I want breathable and highly waterproof (hence the driducks material). We get a lot of rain here in South East Texas but a lot of times it doesn't last very long at a time so I figured a bivy might make sense.

I'm not sure how I'll like using a bivy without a tarp but given my new found addiction to making gear I thought I'd give it a try.

Larry,

Two of the three Quest under 3 oz. offerings are not identified. Suggest you call them to see if they will disclose types, if not brands.

Look at the super article by Alan Dixon on this site first:

http://backpackinglight.com/cgi-bin/backpackinglight/00316.html

It covers one of Quest's three – Xalt, and probably the others if you can find out what they are.

Quest will often provide swatches also, for testing. Some prefer a garden hose. I prefer to stretch the fabrics over embroidery loops and leave them covering bait buckets on my deck before a good rain. Don't have to wait long here in NE.

Agree with you 100% that you need a WPB on top to keep out heavy rain, and also to transmit water vapor so you don't get wet anyway.

Hope this is helpful.
Sam F.

Thanks for the info and the link. I'll send them an e-mail and review the article more carefully once I get some sleep. It should be helpful.

Momentum is water resistant, but quite distinctly not nearly waterproof as primary shelter rain protection. You would get wet using that as a bivy material without shelter.

I've had good luck with many quest products and customer service. I did not have good luck with the lightest wpb material I got from them. The coating came off simply by dragging a finger across the surface. That didn't inspire any confidence in its ultimate waterproofness! If you were using it in a jacket that would have a free-hanging mesh liner it would probably be adequate. Or perhaps as a down jacket shell, caressed by down on the backside. I dunno; you might ask for a sample piece to check out for yourself first. Or a 3-ply material would be ok…

No 2-layer laminate is going to have adequate abrasion protection for bivy use. I can easily scrape the ePTFE layer off of 2-layer eVent with my fingernail, although it's not massively easy.

2-layer WPB's are meant to be used with some kind of backing, or between layers of fabric, and honestly, if you're making a jacket, I'd definitely trust the 3-layer stuff over 2-layer with a liner, and it'll probably be lighter.

Must dissent.
Many 2 layer WPB's are quite sturdy. My Patagonia Specter, original edition, has had pack straps rubbing against it for many a day and shows no sign of wear on the inner surface.
But yes, that is why we need to order samples first – to see what quality the stuff is, especially if the make is not identified.
Sam

While you can scrape off some teflon from 2 layer gore/eVent
type laminates, in some applications it may still last
long enough to be a worthwhile weight trade-off.

Even after you scratch off a good amount of the laminate, you
will find it is still much more waterproof than any of
the uncoated hot calendared fabrics such as Quantum or
Momentum.

Jardin notes using two layer Goretex successfuly for
through hikes for pants.

I have had the same experience with
some 12 year old two layer home made Goretex pants. Except
for the obnoxious bright green color and the noise they
make, I really like them. Am currently looking for some
2 layer fabric but in a more subdued color and with a napped
finish that isn't so noisy.

While I would not use a two layer wp/b fabric in the
shoulders of a stand alone rain parka,
in a bivy there would be little scratching going on unless
you stored your stove or crampons inside.

Interesting point that I'll have to concede. Obviously I'm having a hard time with this one in breaking free of the "bomber" mentality.

I guess if it's just going to have a quilt rubbing against it regardless, the abrasion shouldn't be notable.