Did'nt want to hijack the current sil thread, but it has raised a question in my mind about the what appears to me to be sil bought at walmart.
I was working in a large city and found mine in 2 out 5 stores visited.

My material looks and feels close to what I saw at REI, mostly stuff sacks. Nothing I saw at REI said silnylon, rather silicone coated nylon.
My stuff is very thin and kinda shiney ripstop weave. Its not crinkley or noisey.
I can't really blow thru it like I can thru the regular ripstop nylon that was also in the bargin bin.
Now I wonder if I have DWR and not silnylon.

Is it possible to blow air thru DWR?

You can blow air through DWR, just not really.

Here is the easiest way I have found to tell.

untreated ripstop: has the square pattern, frays on the edges, you can blow air though, if you look really close you can see pores and a rough surface.
DWR: has a square pattern, frays on the edges, has that plastically tarp or sleeping bag feeling.
sil: has square pattern, does not fray what so ever, it has the same plastically feel as a tarp.

It's hard when you don't see a lot of fabric to know the difference. The people working at walmart are usually no help.

You can blow air through DWR, just not really.

Here is the easiest way I have found to tell.

untreated ripstop: has the square pattern, frays on the edges, you can blow air though, if you look really close you can see pores and a rough surface.
DWR: has a square pattern, frays on the edges, has that plastically tarp or sleeping bag feeling.
sil: has square pattern, does not fray what so ever, it has the same plastically feel as a tarp.

It's hard when you don't see a lot of fabric to know the difference. The people working at walmart are usually no help.

Thanks, if thats the case then I probly have DWR.
The cut edge was frayed when I bought it, I'm cutting it with a sharp wood burning tool now, no fraying.
I still like it, oughta make a good light tarp. 22yards only weighed 30 onces.

If you pull at the edges and it frays it is DWR. It probibly is from the sound of it.

It will make an ok tarp. But water will pass through it. On DWR it is a coating ment to keep out some mosture. On sil the silicone is completely soaked through the fabric. Making it waterproof. The DWR is ment to breath. It would make a great sleeping bag.

Either way, good luck with it.

It definatly held up well to the hi pressure hose test. Pressed the nozzle right up to the fabric. No water came thru. Think I'll go ahead and make a tarp of it and see how it does....Thanks H.E.

Sounds cool. Let me know how it turns out. I hear people making tarps out of DWR but never seem to hear how they worked out.

Also if it helps here is a link to directions I used when I made my hex cat cut tarp for hammocking. Not the best design for a ground tarp, but it has good directions on construction. A rectangular one shouldn't be that bad, the next tarp on my DIY list.

http://www.jhatkhat.com/Khat/camping/bcdir/

It definatly held up well to the hi pressure hose test. Pressed the nozzle right up to the fabric. No water came thru. Think I'll go ahead and make a tarp of it and see how it does....Thanks H.E.

Take a 2 gal bucket and drape the end of that fabric down into the bucket, in effect lining the bucket, fill the bucket about half full.

1) If the fabric "soaks" or darkens and leaks like a sieve, it is ordinary fabric

2) If it appears to hold water at first and then starts to bead up, like it is sweating profusely it is likely DWR. DWR will leak through the weave of the fabric but the fabric won't "soak" or darken because the individual fibers are coated.

3) No leaks, likely sil

TAK, Just tested and it performed exactly as you described in #2.
Fabric does not appear soaked, but it lets water pass thru.

Gave my store bought tent fly the same test, no leaks.
Oh well, I'll find a use for this stuff anyway...Thanks.

DWR is downproof. Makes a great quilt or sleeping bag. Or hammocks or windshirts.

TAK, Just tested and it performed exactly as you described in #2.
Fabric does not appear soaked, but it lets water pass thru.

Gave my store bought tent fly the same test, no leaks.
Oh well, I'll find a use for this stuff anyway...Thanks.

One guy over at Hammockforums copied his rainshell in DWR and made a sweet windshirt. You can make a hammock, a hammock sock. You could probably make your own custom fit pack cover and do your own sil treatment on it with a brush. I'm sure there are other uses

Oh, and DWR is the perfect thing to make a down or climashield quilt from.

DWR is not a fabric. It's a temporary coating.

The square pattern in the nylon is known as rip-stop. It has nothing to do with how waterproof or breathable the fabric is. It merely stops or slows rips, as the name states.

DWR fabrics are not necessarily downproof. Downproof fabrics are usually a very tightly knit, fine thread weave, sometimes run between hot rollers and compressed or calendared (sp?) to flatten the threads making the spaces between them smaller. It usually is shiny and crinkly. Downproof fabrics can be ripstop or non ripstop weaves.