Awhile back, i had made a double bivy out of all 1443R tyvek. I had used it a few times with my spouse, and was disappointed to find it frayed/delaminated some after those few times–mostly because my spouse wasn’t careful and would stretch the material sometimes while sitting up or when rolling around.
I also did some tear tests and wasn’t impressed. But i think this material still has promise when reinforced with a woven material. I’ve been toying with various different ideas of making a highly water resistant bivy–primarily for the use of cowboy camping with a flat tarp or small shaped tarp tent. The reasoning is, i like to cowboy camp, but if i happen to get caught in some unexpected rain in the middle of the night, then i have enough protection to keep my down quilt dry.
Initially, i wanted to treat some fabric with silicone for a truly durable DWR, but it’s hard to find non DWR treated, lightweight fabrics and Richard Nisley recently informed me that it’s probably harder to fully get rid of factory DWR’s than i initially anticipated. So, back to the drawing board.
Reading some past threads and testing about Argon Sil made me wonder if it could be considered a somewhat EPIC “like” fabric. With an average HH of only around 750, it must have some air, or at the very least, water vapor permeable areas. Oddly though, some areas tested with a rather high HH, which is presumably due to an inconsistent coating method/coating.
So, ze plan: I recently bought some Argon Sil (Dutch has some left, but you have to “custom order” it). I’m going to help create some more regular air permability, by running it folded under a sewing machine with no thread. I’m also going to prematurely “age” it a bit by washing it a couple times.
That will be the outermost layer of the bivy. The more fragile and UV sensitive polyethylene tyvek material will be in the middle, under the Argon Sil, sort of like a WPB “membrane”. The sides will be extra reinforced by folding over a few times with the Argon sil material, and then long stitched. Underneath the Tyvek, will be mostly nylon tulle for potential summer or warmer weather use.
1443R Tyvek weighs around 1.25 oz/yd2 (can vary a bit though), Argon Sil weighs about 1.1 oz/yd2 and nylon tulle about .3 oz/yd2.
I haven’t decided what i want to use for the bottom material. I have some membrane silpoly and some silpoly PU4000 material i could use. The latter would probably be better overall, both as durability and waterproofness goes, but will be a bit heavier.
I don’t count the nylon tulle as weight towards the water resistant fabrics, just as i wouldn’t count eVent and mesh together in a bivy that used both. So i’m looking at 2.4 oz/yd2 composite material for a very, very highly water resistant top, that “most likely” will have air permeability greater than the most air permeable eVent. Even if it’s just 1 CFM, that would be fine by me.
The 3 layer (well more like a 2.5 since the tulle adds almost no air resistance) system, should cut down on the condensation near the quilt/bag issue over say a straight, pure Tyvek bivy or a bivy with solely an EPIC type top. The larger “pores” in the Argon Sil should avoid some of the issues with EPIC like material in colder weather (water vapor freezing in the fiber interstices). Certainly if caught in heavy enough rain, water could get through those same pores, BUT how likely will they also get through the Tyevek material underneath, with little force or pressure to push it through? And even if it somehow makes it through the Tyvek layer also, how likely would it be to get through the DWR quilt material?
While it may not be technically “waterproof” (1500 mm HH), it would be effectively waterproof for the purpose of protection until a tarp or tent is set up. Best of all, no stupid non-D/WR finish to refresh.
I plan to apply this same combo of 3 layer material to a section of a poncho (upper chest to stomach area). The poncho i have, i originally put Maxima ESD fabric on that same above area, but i want something with more water resistance.
