Most Breathable Bivy?

Well whoever named it needs to watch out:

http://www.pertex.com/fabrics/endurance/

Can anyone confirm one way or the other?

You're right 10X10 DWR nylon

I guess cause its not a membrane its not copyright infringement?

We can all learn something here LOL

What does that mean as a description of the fabric's qualities?

DWR not WPB

err sorry

water resistant, not a waterproof membrane

Similar to Pertex, gotcha.

Pertex is a brand

Similar to Pertex Quantum (i guess.. this is nearing the extent of my fabric knowledge. maybe more similar to Pertex Microlight… dunno)

"Which fabrics are Water-Resistant/Breathable and which are Waterproof/Breathable. I know Pertex is the former and Goretex is the latter, any other examples worth knowing about? I'm fairly certain I want the former, since I'm using a tarp. I want the bathtub waterproof bottom (hopefully tough stuff) and a nice, light, water resistant top for wind spray and bugs. And good netted venting so I don't condense all over myself."

Keep in mind there are different types of "Breathable" and different levels of water resistance. For breathable fabrics you have vapor permeable and air permeable.

Vapor permeable fabrics have membranes that absorbs water like paper. The water once in the membrane works its way to the outside where it again turns to vapore and is carried off. Air however will not flow through it. Most WPB fabrics that use polyurethane membrane are only Vapor breathable and they typically don't breath much until interior humidity gets high. Breathability specs for polyurethane WPB fabrics are typically well below Event. Also you won't see a CFM rating for polyurethane WPB fabrics simply because air won't flow through the membrane. Pertex Shield is an example of this type of fabric. I don't think vapor permeable Membrane fabrics are a good choice for bivy's

Air permeable fabrics like event have very small holes that allow air and vapor through but don't allow or make it very hard for liquid water to get through. Event has a hydrostatic head of about 25,000mm and a CFM rating of 0.5 (If I remember correctly). If you increase the breathability (higher CFM)the hydrostatic head goes down. So when you get to ordinary fabric such as Momentum 50 your hydrostatic head goes to almost zero and the CFM ratting goes very high.

"I'm specifically buying this setup for conditions where my hammock is unusable due to high winds, intense rain, and the risk of falling branches. I am buying this for cold, wet, windy storms in the middle of clearings."

Momentum 50 and Momentum 90 DWR fabrics without membranes. bivys made from Momentum are designed for use under tarps to protect against water spray. But based on your concern of rain in windy conditions I think you are looking for something more than DWR fabric. A fabric with some hydrostatic head would be better. Event would meet your needs. There are some Event Bivys on the markets but most weigh more than your 16oz target.

Tyvek isn't waterproof but with a hydrostatic head of 850mm for 1443R makes it much more resistant to rain them Momentum and possibly good enough to meet your needs. There have been some post on the MYOG forum about tyvek bivys made from little more than Tyvek 1443R and Tyvek tape that weighed about 7oz.

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=46661 ).

I can barely sew, and I have no machine, so Tyvek is out. I feel like I'm right back where I started… Anyone have a recommendation for a Tyvek bivy or a first-hand experience with the MLD Superlight that contradicts the science?

Dude, despite your claims that you do your research, you must not read all the posts above. Tyvek/Polypropolene bivy from Miles Gear

http://www.milesgear.com/UberBivy.html

And my experiences with a MLD superlight is condensation nearly 50% of the time

http://40yearsofwalking.wordpress.com/2011/07/04/the-bivy-condensation-conundrum/

a quote from my own piece:
"I have scoured the internet and there is no miracle fabric, all bivies have condensation/frost from time to time but the ones with the least mentions of condensation are made of all eVENT like the Integral Designs All eVENT bag cover (now discontinued) and the OR Advanced Bivy, both with vapor and air permeable top fabrics. [8, 9, 10]

The ones with a breathable nylon top with a good DWR and minimal silnylon floors, but without high bathtub floors, are the next best. From reports there seems to be something about the waterproof bathtub floors that leads to more condensation. This is apparently why the ones made of all eVent (top and bottom) have fewer reports of problems with condensation.

The worst offenders are any of the polyurethane membrane/WPB materials that are only vapor permeable like full Gore-Tex, Montbell DryTec, Mountain Hardware Conduit, etc. I have used or been around many of these and they all have had bad condensation problems.

One of the things that seems to happen with the vapor and air permeable fabrics (eVent, Gore-Tex FLO2, Gore-Tex Respiration Positive, Exchangelite and the less waterproof Gore-Tex Dryloft now Windstopper [10]) is that the membranes are laminated onto fabrics, and many lined with Tricot, that seem to help wick or pass the moisture through the material. I feel that this is why my old OR bivy had so few condensation problems, it has an almost cottony feel to it. The problem with these fabrics is they are heavier and the lightest of these bivies on the market are 13 oz. and up, with most around 18 oz. and they are crazy expensive ($200 plus)."

I have a double bivy from Miles Gear – and while I've only used it a few nights, I've never had any condensation problems. On the other hand, I almost always had condensation with my Big Agnes Fly Creek UL2.

The upper material he uses is very breathable and waterproof; he describes it on the "Uber Bivy" page. The only downside is that it is a little bulky IMO, but this may be because he uses a Tyvek floor. The bivys come seam-sealed if you want and you have several options. He built in a mesh screen at the entrance for me.

" I am buying this for cold, wet, windy storms in the middle of clearings."

For these conditions I use a Duomid with a montbell breeze tec bivy (8oz) and completely waterproof.

Bivies by themselves will not keep you dry.

The Duomid is great in the wind and rain. The Montbell bivy handles any spray that comes in or flows under if the clearing becomes a lake.

The Montbell Breeze Tec breathes well and is lighter than event and costs less.
It doesn't have a full hood but you don't need it with the Duomid.

In the winter, for wind and snow I used the Integral designs Wedge Bivy which I picked up on ebay for 1/2 price.

Also Locus Gear in Japan has a new Pneuma Bivy eVent which is 10oz but $331 for the large. http://locusgear.com/products/bivys/pneuma-bivy-event

I actually put the Montbell breeze tec bivy in the bathtub with 2 inches of water for several hours and the paper towels I had inside came out dry. The seams are taped.

Are you looking for the most breathable and still waterproof or are you looking for the most breathable? Most breathable is no bivy at all (Ha). Most breathable and waterproof is eVent, and I would also argue more breathable than any fabric below freezing. At least this has been my experience.

–"I have scoured the internet and there is no miracle fabric, all bivies have condensation/frost from time to time but the ones with the least mentions of condensation are made of all eVENT like the Integral Designs All eVENT bag cover (now discontinued) and the OR Advanced Bivy, both with vapor and air permeable top fabrics. [8, 9, 10]

You say the OR Bivy is eVent but their site says GoreTex Respiration 3-layer fabric. Something I don't know?

I actually like the OR Bivy.

These days I don't take any bivy, I use my duomid, an epiphany quilt which can handle the spray on it's own and a large gossamer gear 2 oz plastic sheet and a lighter tyvek for making kites. Most trips the plastic stays in my pack but if it looks like it will rain heavy I use the plastic and raise up the perimeter.

I just bought a cuben pyramid shelter from Locus Gear in Japan.
Looking at their other products I saw they have an all eVent bivy and also a tyvek bivy.

Event:
http://locusgear.com/products/bivys/pneuma-bivy-event

Tyvek:
http://locusgear.com/products/bivys/pneuma-bivy-tyvek

No relation or affiliation, just happy with a really well made product and buying experience, pretty short waiting time and general advice I got.

The site is in Japanese but if you send the owner an e-mail he will answer any of your questions in English. You can probably also order that way.

I personally got a Bristlecone bivy from Katabatic gear (silnylon bathtub/pertex upper with mesh) and it is made incredibly well too.

Can highly recommend any of these three options.

…

So this article answers most of these questions about standard Gore-Tex (a PU-PTFE) and eVent and eVent like PTFE only membranes (Exchangelite, Gore-Tex Respiration Positive, (used in some of the OR bivys), Gore-Tex FLO2 and Gore-Tex Windstopper

http://www.backpackinglight.com/cgi-bin/backpackinglight/00316.html#.UTYoajCG3fw

And some more details in this article

http://www.backpackinglight.com/cgi-bin/backpackinglight/orwm_2011_wrapup_waterproof-breathable_technologies.html#.UTYrAjCG3fw

The best way to handle condensation with a bivy is to not use one. The history of bivvy use is for high altitude mountaineering which involves below freezing temps. Condensation freezes and the ice can be shaken off.

With sub 1 pound shelters and highly water resistant sleeping bag shells, as well as highly water resistant down, bivy use really has become obsolete for backpacking. There are no benefits apart from draft protection for use with a quilt. But even then, with the additional weight of a bivy, just use a sleeping bag instead.

…

What Dave U said and read the articles I reference above about the PTFE's and the PU-PTFE's

"This would explain why the USGI bivy seems to have the best anecdotal reputation for low-condensation."

This was my experience over the years with the waterproof USGI bivy as well. Once I learned not to breathe into my bivy, my condensation issues were almost none. Too bad it’s 2.5 lbs. I've always used synthetic bags with my USGI bivy so maybe a down bag would have a different experience.

I am trying to nail down exactly what you are looking for here…I think you are too.

You mention:
1)you are going to use the T.S. tarp when the weather is too nasty for the hammock or no trees.
2)you want something to protect your insulation from spray and wind chill
3)minimal condensation
a) not sure weather you need wbp or wrb
4)full coverage with a net window
a)no (minimal?) other netting
b)100% bug protection

I think bc of 1) you shouldn't need 4b (bc bugs typically arent around around in this weather) but I understand trips can span different bug/weather scenarios – maybe compromise with an open face bivy and a mosquito headnet?

I think if 2) is the main purpose: wrb material is the way to go. Id want a long zipper and the ability to suspend above your insulation. If it has integrated head netting I want to be able to unzip from above my head. I don't think anyone makes this so i'd see if borahgear or similar would make one to my specs.
But if you are willing to get past the bivy term i'd look at this inner made for the T.S's "normal" pitch:
http://www.oookworks.com/OookStar.html — maybe you could get them to extend the nylon walls up much highter

If you are thinkingthe weather might ever be too much for the T.S. maybe consider the milesbivy or the locusgear event one(if it fits you).

I also have no sewing skills to speak of. My first Tyvek bivy was made with no hood, no sewing, and held together by 3m super 77 and sealed with Tyvek tape. The only part I had help with is having someone sew the zipper on. Super easy, and the best part was I got to make it as wide/narrow as I wanted.

Then I got lucky and had my Mom sew me a Tyvek bivy with a trapezoidal foot box and hood (hurray for moms).

But, if you are thinking of an eVent bivy….the Pneuma eVent bivy by Jotaro at Locus Gear is dead sexy.