MYOG Pertex Quantum – Cuben Fiber Bivy

[carlos fernandez rivas]

bill why you decided use cuben fiber in the hood? a place very sensitive to condensation due our breath ?

[Bill Fornshell]

Carlos,
I will use a balloon to hold the hood open and away from my face. Sort of like a little tent with a big door. I have learned how to blow up a balloon so I don’t need the balloon pump. I also learned how to tie a slip knot so I can untie the balloon easy and use it more than one time. The balloons weight less than 3 grams each ( I found some stronger balloons) and for a hike with a resupply schedule of 3 to 5 days I will only carry one balloon for the Bivy. I am using my home made balloon bed and the balloons are the same size so I will always have a couple of extra balloons if I break one.

The Pertex Quantum is also 3 times heavier than the Cuben fiber. I think we fuss way to much about condensation but If condensation becomes to big a problem on a given night I can push the hood back and out of the way.

Testing will see if this works. If it doesn’t work I can always cut the Cuben hood off and replace it with Pertex Quantum.

[carlos fernandez rivas]

Im really interested in this test ….

During the last 10 years I used vivy bags as my unique shelter in most of my activities (mountaineering climbing and backpacking), I tried a lot of bivy bags (gore tex, paclite, quantum, epic….) in every weather condition imaginable, and in some situations deal with condensation in the hood is the worst problem.

If the solution is a ballon (it’s a really brilliant idea) I will become the president of your fan club

And thank you for you excellent posts ..

carlos – Spain

[Eric Noble]

Bill, glad to hear you no longer need a pump to blow up the balloons. What made it work for you? Are you looking a little more like Marty Feldman? :)

[Bill Fornshell]

Carlos,

I have an old OR Advanced Bivy that uses 2 hoop poles. The system had worked very well for me but the poles were to heavy for this Bivy. I had a long piece of Ti wire like BMW sells but just longer. The Ti wire was border-line to light for the Pertex Quantum hood. That was another reason I went with the Cuben Hood. I had been playing with the small balloons for a different project and thought try the balloon for the hood. A balloon worked well and held the hood up really nice.

I am working out the details for version 2 of the Bivy. It will be designed for use in rain and maybe even snow and will not require a tarp. It may be heavier than this Bivy but lighter than a Bivy and a Tarp used together. It is looking more like a baby solo tent when set up. Using a really good and light WPB fabric, Cuben fabric and a couple of balloons or something that inflates I hope to stay well under 5 ounces.

If this new Bivy design works in snow then I can use the weight saved for more insulation in another Quilt/Sleeping something and maybe get a Sub 2 or 3-lb gear list that will work below 32 degrees or maybe lower.

Eric,

I have a friend, my balloon man, he sells balloons but his main job is dressing up like a clown and doing parties. I called him about getting some balloons and went to pick them up yesterday. He said not many people can blow up the small ones but most can learn how to blow up the bigger ones. So for about 30 minutes he shown me how to do it. I can blow up the 360’s and even though they are a little bigger they will work for the hood of the Bivy. They also are the same size as the CheerStics so they will replace the CheerStics in my Kilt/Air Pad Shell. When I blow up the 360’s for the Air Pad I will tie them off at about 24″ long. He also showed me how to tie a sort of slip knot that I can take out easy. With the stronger balloons and the slip knot I know I can use them more than once. His balloons are stronger but not heavier (3 grams each) than the ones I had been using from Hobby Lobby.

My eyes were back to normal this morning.

[Christopher Plesko]

Heh, what WPB fabric? A solo shelter under 5oz sounds pretty nice even if it’s very small. Finding good light WPB fabric seems the last piece of the puzzle not really available to MYOG/DIYers. If I could buy something along the lines of the stuff in my montbell ul bivy I would be very happy. It might not breathe like EVENT but it’s good enough for me and much lighter.

[mark henley]

Bill,

I realize that you had the Pertex Quantum already …. but do you know of any suppliers that still sell Pertex by the yard?

[David Olsen]

I got some 2 layer XCR like used in the montbell
bivys. Also some 2.5 layer paclite. They both weigh
2.1 oz per square yard (versus Epic at about
1.7 and eVent 3 layer at about 2.5). Price $16/yard.

Pertex Quantum is not sold by the yard retail.

[Bill Fornshell]

Mark,
I have had the Pertex Quantum for 2 years. I don’t know anyone that is selling any as David said, it isn’t sold retail.

Thru-Hiker.com has something called Momentum 90 (about 1oz a sq yard) – $11.95 a yard. I have about 5 yards of it. I would say it is as good or better than Pertex Quantum (about 0.91 oz a sq yard).

Chris,
I am trying to work out the square yardage needed and then will see what is available. I know David has the different fabric he listed above and eVent would be a good one. I may try all Cuben as I am designing this to have a good vent system.

David, What color is the 2.5 eVent?

[David Olsen]

I don’t have the eVent for sale anymore. The lightest I tested was a blue 3 layer. Price is close
to $20 per yard plus freight from Japan, a 5 month
wait and a 700 yard minimum last time I checked.
Ouch.

I do have the gore products and the 2 layer XCR
should be very breathable, I have seen no data
on this one, only for 3 layer XCR or 2 layer standard
Goretex, so I don’t know the vapor transmission rate.

In gaiters and pants and overmitts, I have not been
able to tell any real world difference between 2 layer Goretex and 3 layer eVent. I haven’t
tried an eVent jacket, which would be the real test.

[D G]

David,

Do you have any info on the new EPIC fabric? It’s of course only water resistant and not water proof but I read on the Nunatak website that they have tested the newest version of EPIC and it’s supposed to be as breathable as before but more importantly much more water resitant.

Cheers
Dan

[Christopher Plesko]

David,

Might try out the 2layer stuff once I get the yardage nailed down. I’m assembling a “want” list of fabric and materials to order. Too bad we don’t have anything lighter than 2.1 oz/yard for WP/B. Maybe epic is good enough too although I haven’t tried it. I really need the breathable stuff in the footbox and the hood when using it as my only shelter so I can hunker down during a storm.

That being said my DWR pertex windshirt really does just fine in most of the rain conditions I encounter and based on the reviews of the superlight (6oz) real rain jackets I can’t see a reason to “upgrade”. If I seam seal it then it would survive a pretty substantial summer storm at only a little over 3oz.

[Bill Fornshell]

I decided to start a mock-up of the size I want the new Bivy to be to get a better idea of how much fabric will be necessary. Some rough math seems to indicate that the top part will take about 3.34 sq yards and the bottom will require about 2.07 sq yards. I would add a bit for seams and mistakes.

These number do not reflect a small front vestibule, removable bug net at the front or the material for the vent system. If I can come up with a really good vent system I might try Cuben for all of it.

The Cuben would put the total weight at under 2.5 ounces.

[Aaron Sorensen]

Hey Bill,
I have another idea I use for my balloon bed.
Just inflate the balloons once with the pump. It stretches it out enough that you can orally inflate it the next time.

As far as the 1.3oz ground-sheet goes, my cut to torso length pad from gossamer only weighs 1.3oz. You would probably only needed to be worried about ripping the bottom where your torso is any way. The good thing about the 1/4″ pads is they add a decent amount of warmth for the weight and they fold up in your pack very nicely.
Besides, aren’t you already using your cheer-stix pad with this? That would seem to be adequate.

[Eric Parsons]

I’m a bit new to alot of this and trying to learn as much about the available fabrics that I can. I’m looking to construct 2 things: a winter bivy / over bag with a thin layer of primaloft. And a single person tarp for winter conditions. I live in Alaska and Christopher I’ve done the Ultrasport race to Mcgrath, so feel free to ask any questions.

I’m curious as which fabrics handle condensation the best. Rain is not an issue but frost which then melts on the top of my sleeping bag is. I was thinking of just going with SiNylon for the tarp but if I could find something as light with a bit of breathability that would be cool.
Thanks

[E. A.]

z

[Bill Fornshell]

Hi Eric,

I was in Georgia hiking when you posted this and I didn’t see it till now.

I have three different fabrics that I could use for something like a winter bivy. I will be making one soon. I have some Pertex Quantum that I have had for some time and I don’t think I can get any more. I have two really nice WPB fabrics that are sold by Thru-Hiker.com. One is Epic Malibu at 1.7 oz a sq yard ($12.95 a yard) and the other one is Momentum 90 at 1 oz per sq yard ($11.95 a yard). I will be using the Momentum 90 on one of my next Bivy’s. The Momentum 90 is a really nice material and if I didn’t have a little Pertex Quantum I would use it for about everything that takes a good/light WPB material.

I would also think about using Climashield XP vs primaloft. You can read about it also on the Thru-Hiker.com site.

As for the question “which fabrics handle condensation the best” I am not sure there is a good answer for that. I have no idea and don’t worry much about condensation. For my tarp I use a very light weight material called Cuben Fiber at about 0.35 oz a sq yard and just live with any condensation I might get. My Bivy shell is WPB so it has never been a big problem.

[Bill Fornshell]

Way back in September Carlos asked about my use of the Cuben Fiber for the hood of the Bivy and about condensation.

I have had a chance to use the bivy for 6 nights on my Georgia Hike. Most nights were a little windy and I kept my head inside the hood area. When I thought about it I tried to keep the hood open a little. It never got bad enough to try the balloon idea. I did get a few condensation drops one night when I was real close to a river but never enough to worry about. I think the breeze blowing through my tarp set-up most nights may have helped. The weather which was cool and dry might also have helped. I slept on the ground with just a ground cloth two nights – no pads just the soft leaves – stuff – etc.

[Eric Eaton]

Hi Bill,
I’ve been admiring your work on your many posts and wonderful pictures.
This bivy project was of interest to me, as I had a last minute invite for a weekender (high winds, rain/snow, 40’s-20’s in Mass), but no bivy to match my poncho/tarp. Took me about two hours to design and sew one. I purchased some Pertex Quantum from Scottland (last year or so?), and used the silnylon from an unmade Ray-Way tarp. It came out better than I hoped. Even though the trip was cancelled, I went out for an overnighter (30’s, 50+ MPH gusts, poured hard rain and snow) and am pleased to annouce I stayed snug-as-a-bug-in-a-rug for about 8 ounces. Thanx for the inspiration!
I sized the hood area to hold all my gear, so I could sleep with my feet on my empty pack. The hood opening runs across at about nose/mouth level, and closes down with an Aircore cinch line held with a tiny spring-loaded-thingie off to one side (so it wouldn’t tickle my nose). On each corner is a small grossgrain loop for stake-down points. To make the corners, I just sewed everything else first, then tucked the corners inside while playing with the angles and stake loops, pinned the whole works together and BINGO!
Also, I did try including a loop over the face area of the hood, but placed it too far back. In the field, I found a pebble on the inside with a loop of Aircore on the outside tied up to my poncho/tarp guy worked great. I’m thinking that might be easier and lighter than a balloon.
Also, also, a new friend makes sails for racing yatchs. He saw me making my bivy, and offered me “scraps” of cuben fibre for my next set of projects. I have no way of knowing how large or thick a “scrap” would be, or how many he’s talking about, but if anyone is interested then please email me at [email protected] and I’d be happy to share for free.
Thanx again Bill.
–Eric

[Joe Federici]

Bill I didn’t see a sorce listed for the Pertex Quantum you used. I’d like to use some for another project as I’ve heard great things about it.

JFF

[Bill Fornshell]

POSTED BY
Joe,

I have no current source for Pertex Quantum. What I have I got over 2 years ago and that source is gone.

When my Pertex Quantum is gone I will switch over to Momentum90 which is sold by Thru-Hiker.com.

[hugo pilon]

how ,where to buy quantum,cubin-fiber?

[Johnathan White]

I just found out from a sales guy at Pertex.com that they do sell it at 5.50 a Sq yard. So what is the catch? You can only buy it from them at this time AND it is available in 500 yds per color minimums.

[Johnathan White]

Maybe we can all go in together on a roll eh?

[Bill Fornshell]

Johnathan,

Did you get any other details such as colors available, shipping costs, etc?

SUBJECT Re: Source for Pertex Quantum ON 11/10/2006 08:31:22 MST
Maybe we can all go in together on a roll eh?

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