what are your thoughts on impulse sealers?

Hello all -

I ran across this document that breaks out the different types of tyvek. It lists material weights, Hydrostatic Head, Tensile Strength etc. This might be helpful when selecting which type you want to use for future projects.

http://www2.dupont.com/Tyvek/en_US/products/tyvek_styles/tyvek_styles.html

- Bryant

I got the chance to test out the Bivy in some really wet and rainy conditions this weekend and wanted to post an update.

Weather during the two nights I tested the bivy was very, very wet. I was camping above the ocean, in a very thick fog/mist, with drizzling rain all night and a period of heavy sustained rain for about 3 hours during the middle of the night. Since I was using a non-DWR nylon down bag, it was very important that the bivy keep my bag dry. It certainly lived up to the test and exceeded my expectations.

The bivy is for purposes of tarp-camping, much more water resistant than a DWR nylon bivy. Despite the fact that condensation and rain was pouring down even inside my shelter, the bivy kept my bag dry. (I was somewhat disappointed with my shelter in these conditions as when the rain was pouring down it felt like it was raining inside my shelter. Everything in my shelter, other than the clothes in a silnylon dry sack and my bag in the bivy was absolutely soaked. I imagine this was due to the condensation/mist being pummelled off the shelter by the hard rain.)

Furthermore, a puddle formed under me during the night and water did not soak up into the bag from below. Since I was using a 48" length pad and no ground cloth, the only thing separating the bag from the wet ground was the bivy, and I did not notice any water coming through.

The one thing necessary to make this bivy truly stormproof in these conditions is a zipper or other means of closing it up. Water was splashing in from above and around my shelter into the opening of the bivy, and I eventually just scooted my bag and pad down to hunker down under the bottom half of the bivy to keep dry.

The next day I dried out the bivy and my sil-nylon shelter in the sun and noticed that the bivy dried more quicky than the shelter. It did accumulate lots of dirt and debris which is not easy to get off, but again, I didn't use a ground cloth and that could be avoided easily by doing so. (I wanted to test the waterproofness of the bivy underneath to see if water would come in from below--hence no ground cloth.)

Here are some pictures of the softened bivy:



Thom has offered to make me a bivy sized smaller for the use with a smaller neo-air pad. I'm hoping he can make use of some mesh to create a bug proof bivy as well as a zipper to fully enclose the bivy for stormy conditions.

Edited by Rezniem on 05/07/2009 13:31:01 MDT.

Nathan,
Thanks for the testing update and pictures.

With the recent wet weather pattern here in the PNW I also have had an opportunity for personal testing and with similar results. Something you did not address is warmth. This material is warmer then other bivy materials I have used including both epic and event. The breathability and weather proofness has continued to impress me when testing.

Adding a zippered closure and bug protection is worth considering on future versions. With my limited sewing abilities such design additions would likely require sewing help.

Yes, as the first two tests, the bivy adds much more windproofness than simple nylon and is much, much warmer. You can really tell that the material is insulating as well as providing protection from water.

Thom, et al,

I was wondering if there has been any recent progress on this project, especially from Thom on the design. I am considering this project for Fall/Spring hiking in the Oregon Cascades and Coastal range. Lots of rain!

Has anyone used type 14 (soft structure) Tyvek for a DIY bivy?

I'm going to try making a custom pack cover for my Osprey Exos 46 with type 14 Tyvek. Seems like ideal material for this type of project; much quieter than type 10. I plan to post the results of that project on BPL.

Edited by kencharpie on 11/04/2009 04:38:59 MST.

Ken, PM Sent!

Better late then never.

I made one.
Have not tested it yet.

I did a design with a bathtub floor to fit a neoair, but made the diameter too small. It will work with the pad on the outside. I set it up with a hood supported by stadium balloons.

I tested the material for waterproofness.
Made a cone and filled it up with water and it held for days. I think it eventually evaporated out.
It weeps, then stops.
If you touch the outside it will start weeping again.

Fine for a bivy though.

The fabric or paper I should say, is soft on one side and harder on the other. The soft side can seperate pretty easily from the waterproof membrane.

I am going to build another though. This time simpler. Since it is basically a tube, I am going to cut to shape, start at the neck with one very long piece of tyvek and fold it at the feet, down to the head, fold again at the head with a hood flap.

The footbox and head will be made similar to a square bottom stuff sacke where you clip the corners. Something simple like that and glued.

So, I threw together two Tyvek bivies yesterday afternoon for a quick overnight trip with a buddy. A tent was not practical where we were going, so I thought why not try a bivy.

I had a partial roll of Tyvek "Stucco Wrap" around, so I used that. I just cut it to length, folded it over and glued it together. In other words, the seam was on the short side. The width of the bivy was equal to the width of the Tyvek material.

Well, there was a LOT of condensation last night. Standing mist in the valleys and the grass was drenched.

I expected (hoped) for the inside of the bivy to stay dry, but I got a lot of water in there, drenching my bag.

Can someone offer some insight on what happened? Was it just the conditions? Should I expect it to be dry inside?

I have only used tyvek "house wrap" material in the projects I've completed. I have yet to have any issues with condensation in any form regardless of weather conditions. I have done multiple material tests with no leaking and or weeping issues.

Is it an issue that the end of my bivy was wide open?

Being the actual width of the Tyvek material, was the whole thing just too wide?

I basically had a large envelope with one end open that I slid into. I thought it would keep my bag dry from the ground and condensation.

Does anyone know if "stucco wrap" is different from "house wrap" besides the ridges?

Is it an issue that the end of my bivy was wide open?

Being the actual width of the Tyvek material, was the whole thing just too wide?

I basically had a large envelope with one end open that I slid into. I thought it would keep my bag dry from the ground and condensation.

Does anyone know if "stucco wrap" is different from "house wrap" besides the ridges?

Thom, it's been awhile since you've posted on this thread. It seems like the lightweight design of your Tyvek bivy would be perfect for my backpacking needs under my siltarp. I am planning Sierra Nevada trip for summer.

Has anyone thought of using soft tyvek for the top of a bivy and housewrap for the bottom? Soft tyvek is somewhat more breathable and highly water-resistent, but not waterproof (I tested it in the shower). This would help to avoid some condensation issues.

I just made a very simple bivy using soft 1446B tyvek (hydrostatic head in the high 40s I believe). It's UV coated as well, which helps with waterproofness.

I bonded the seams with 3m super 77. They appear to be strong EXCEPT at an angel where the stress is perpendicular to the seam (think pealing a banana). I managed to get the bivy together with only two points (either side of the hood opening) where this is at all an issue, so I might put a couple stiches in there, but besides that, so no problem.

Stood in the shower for a couple of minutes, dry as a bone.

Am going to add some loops so I can pull it off my face, and give it a test run this weekend. It weighs 165g (5.8 ounces), which is a pretty attractive number.

I'll post some photos, final weight and trial results after going out with it this weekend.

I am a complete novice at MYoG (I've made a penny-stove, super-cat stove and firebucket in the last month and that's it), I can't sew, and am really bad at putting things together. But, I was able to make advice. So to all considering a tyvek bivy: just do it! Took me 4 hours or so the first time in my Tokyo apartment.

Got the Tyvek from http://www.locusgear.com who also runs http://magicwand.jp here in Japan.

I finished my tyvek bivy yesterday. I waited until after I rechecked ad re-sealed the seam edges before I softened the tyvek in my washing machine. It helped to soften the Super 77 spray adhesive (thanks for the tip on the adhesive Thom it works very well and is, in fact stronger than the actual tyvek. My design, how ever is significantly different than any I've seem in this thread. I used one piece of tyvek drainwrap (it's slightly heavier than home wrap -2.1 oz/sq yard vs 1.85 oz/sq yard but it's the only kind that contractors use up here in my PNW neighborhood to scavenge). I cut the Drainwrap so when I folded both edges in to form a flat seam along the top, it would taper. I modeled my bivy after simple stuff sack designs that don't have a round bottom stitched in. It's hard to describe (I'll post pictures if people are interested). Anyways it weighs in at 236.5 g so it's pretty light but not crazy light. It's not storm-proof either (with head cover) since I plan on using it with a tarp tent. I'm eager to try it out! I reinforced the "banana peal" seams by over-lapping the intersecting seams and covering the ends with round-corner triangles.
Oh to prevent over spray I used a cardboard box with a 1" x 2' slit cut out, the side walls of The box also contained the wafting/ drifting spray away from my kitchen linoleum and my carpet as well.

It is fun to read that others are still working with the ground cover bivy (GCB)concept. My focus has been on other projects but I still find time to play with the GCB. I'm hoping to work with a local scout group this spring to help with the members each making their own. I will provide the required materials and make my own along with the troop members, should be fun.

I'm hoping to have the opportunity to talk about ultra light hiking and tenkara fishing. I will post project pictures and a report if it all comes together.

Thom
TrailLite Designs

Edited by thomdarrah on 03/19/2011 07:52:53 MDT.

I have been thinking about this project for a while. I bought one of the "bag sealers" from harbor frieght i am goin to pick up some tyvek to mess with see what I can come up with has anyone made a tarp or tent out of tyvek?

Thom,

Several (maybe 10) years ago I made a tyvek overbag out of what appears to be the same material you are using. I tried it inside my double wall tent with the aim of keeping me warmer. I aborted the mission in the middle of the first night because I was getting a lot of moisture build-up inside the overbag. It was starting to wet my sleeping bag.

Temps were around 30F with high humdity. After exiting the tyvek bag I had no condesnsation problems within the tent. The inner tent fabric was more breathable than the tyvek.

I've always sewn tyvek when experimenintg with it. There is a tape specifically made for it, however.

Daryl

I'm planning on making my own Tyvek bivy this weekend (pending my ability to find the stuff at a good price or for free) and was looking for a couple of suggestions:

1. Should I use Tyvek tape or the spray-on adhesive (Super 77 seems to be what most people use)? Any thing else I should consider for bonding?
2. Should I wash the Tyvek before or after I make the bivy?
3. I was thinking about adding a mesh panel at the foot of the bivy for ventilation. Is this necessary?