I've seen tyvek used for everything- tents, tarps, groundsheets, bivys, backpacks, etc... I personally find it a fascinating material. It's roughly the same weight as silnylon, but it's considerably more bulky (judging from my groundsheet).

I also understand that it's a waterproof but breathable material- which leads me to a couple of questions. How does its waterproofness compare to run of the mill silnylon (or silnylon 2nds, since I'm cheap)? Has anyone does HH testing of Tyvek? And as a breathable material- how does it compare to normal myog wpb fabrics like Momentum 90 or eVent or whatever?

Thanks,
BM

Just to clarify M90 isn't wpb. It simply has a DWR coating.

For tyvek, it's pretty decent if you're looking to be frugal and don't mind having to adapt to the fabric. I'm in AZ so don't mind using it for everything since sustained rain is not much of an issue.

>Just to clarify M90 isn't wpb. It simply has a DWR coating.

What exactly is the difference?

Thanks,
BM

WPB is a fabric that is bonded to a membrane that passes vapor, but not water. Think GoreTex for the classic WPB fabric.

DWR is a breathable fabric that has been impregnated with a water repellent. It can wet out, and pass water, but is VERY resistant to water. It is also much more breathable than a WPB fabric.

I have some m90 that my buddy used for a bivy and it is very breathable. And lighter than tradition WPB fabrics, I think.

WP/B has an air-tight membrane bonded to the fabric which allows some water vapour *molecules* but not liquid water to pass through it.
DWR is a coating on the fibres in a fabric which repel water by surface tension for some time. You can blow air through the fabric.

Cheers

Thanks- that clears up a lot of confusion. So, stuff like m90 should be occasionally re-treated with a dwr coating, like, uh- shoot drawing a blank on the name...nikwax (got it!)...?

So then I would imagine tyvek is a lot less breathable than m90?

Thanks,
BM

I have found Tyvek to be less breathable, but I have been using the stiff housewrap.

It is CHEAP though, and darn near indestructible. While my friend was making his bivy from sil and m90, I made mine from housewrap. Even with the carrying bag it comes in at 8 ozs. Not super light, but pretty bomber for that weight.

It is a pain to sew, and you might want to seal the seams with tyvek tape, if you want it to be tougher/more waterproof.

The big downside is that you look like a big grub in the white tyvek bivy, and it seems to be a dirt magnet when it gets worn. Lots of folks love and swear by it for groundcloths.

Don't forget the noise. Unless you're a really sound sleeper who lays completely stiff, the crackling of the Tyvek will keep you up. You can wash the thing multiple times to soften it, but then it gets fuzzy. I love my M90/sil bivy.

Edited by jasonhardt on 02/10/2012 16:55:07 MST.

What do you plan on using it for? I'm considering one of these.

There are also different types of tyvek. I think most of the ground sheets are made from the "home wrap" versions. However tyvek 1443R is softer and much more cloth like. Regardless it's fairly weak material. Good for limited use or prototyping on the cheap, but I wouldn't want to depend on tyvek on more committed trips.

Well, the first thing I'm going to use it for, I think will be for the floor of a inner net / bug tent for my myog two person 'mid shelter that is currently under construction.

I know a lot of people use silnyon for tent floors, but I hear all over that it seeps water, eventually gets holes in it and just wears out. Tyvek is commonly used as a ground cloth, so it just got me thinking. I could just make the floor out of something cheap, and when it wears out, it wouldn't be much of a deal to rip it out and sew in a new one.... And beyond that, I just started getting curious about how it's properties compare to other common materials. If I recall, I think the Tarptent folks even offered a shelter made from tyvek at one time...

And that is a pretty attractive pack. Seems like tyvek would be a great prototyping material.

BM