Sil-nylon fabric

[cracked]

sil- tarps are spray-resistant!

 

Just borrow a sewing machine and do it right. It will be stronger, prettier, lighter, and best of all, the hems won't fray.

[ketch]

Marylou, Ya it was an evolutionary thing to reinforce the corners. First I had just a sheet for a footprint, loved that. Next I wanted lighter for summer so I reinforced the corners so that I could go just poles and fly and leave the tent at home, worked good but doesn't keep the bugs out . My next idea is to try taping up a bathtub footprint but I havn't quite got up the energy for that trial. Still like the Tyvek, if you run it through the washer once it way helps the rattle and doesn't seem to affect the watertightness.

[marylou]

Good, looking forward to getting my piece o' House Wrap in the mail. Apparently there is a lighter kind of Tyvek out there, used for kites, you can buy it here if you are interested.

[ski_photomatt]

I've used a simlar setup on ski trips - megamid w/ sil-tarp as a ground sheet. Sleeping on the tarp is annoying. I never took the time to make certain the dug out snow platform was exactly level before throwing the tarp and sleeping bag down and had to readjust several times during the night as I would wake up and notice I had slipped off the tarp. But it is light, and is water proof, and isn't too bad for a night (I've only used it on overnights, dunno how I'd feel about it for a multi-day setup).

[fern]

 

does seamseal waterproofing goop stick to this SilNylon stuff?

 

Is there a tricky way of sewing a seam that will make it as watertight as possible?

[JoshK]

does seamseal waterproofing goop stick to this SilNylon stuff?

 

Is there a tricky way of sewing a seam that will make it as watertight as possible?

 

There is something called sil-net which is specifically for silnylon. You'll want to use that, not regular seam grip. There is some sort of tri-fold seam that is suppose to be the way to go for equipment, but I still sealed all my seems anyway. With the amount of rain a pissed off cascades storm can dump I figured I wouldn't want to find out the seams leak in the middle of the deluge.

[rbw1966]

You might want to spread some babypowder on that seam sealer too so it doesn't stick where you dont want it to.

[marylou]

Regular Seam Grip does NOT work on Silnylon.

[arlen]

It's easier to sew if you fold masking tape over the seam first. The needle gets gummed up pretty fast, but I got fewer skipped stitches that way.

 

Instead of a grommet, you can always double over the corner and use the rock-and-loop-of-string method. A little duct tape keeps it from sliding off.

 

I used a silnylon tarp for a couple backpacking trips and decided it stretches too much, even with catenary-cut seams. Tyvek is better all around--except for weight.

[JoshK]

How did you have a problem with it stretching? The silnylon gear I have doesn't really seem to stretch much at all.

[arlen]

A combo of rain and wind made it sag and flap too much. For whatever reason, tyvek hasn't had that problem as much.

[marylou]

I have found, using a few different shelters, and both sil/sil and sil/PU....and also stuff with and without caternary cut, that sil stuff does stretch a lot more than good old PU. Especially sil/sil. It's mildly annoying, but a lot of it is remedied by retensioning the shelter an hour or two after pitching. Not always an option, but when it is, I've been able to get the sag out and not have it come back much.

 

Caternary versus non, not much difference in stretch, surprisingly.

[JoshK]

That is one nice feature of the mid...just adjust the pole from the inside for more tension.

[Beck]

sil tarps aren't so slippery you can't use them as a ground sheet... try bracing yourself with gear or parka or whatnot, or a hiphole in the snow...imagine if youre on a thermarest that'd make it slipperier, but on a foam pad and a dirty piece of silnylon it isn't bad, no worse than a piece of plastic... but slipperier than tyvek of course.

 

To sew a seam that's more water resistant, use cotton thread. It swells up when wet and plugs the hole in the fabric. A topstitched french seam is probably the most water resistant...

[cracked]

Cotton thread is weak and rots. Just use seam sealer. And high quality polyester thread.

[Beck]

...the "secret" to sewing weather resistant seams is using cotton thread, and is used by some manufacturers. I still like big globs of seamsealer myself, cracked. just trying to anwser ferns query.

[JoshK]

Well, my mom and I got this thing made. I should really say her because about all I helped with was cutting the fabric and a little bit of sewing. We ended up using this double sided fabric tape that washes away for holding the sheets together for sewing. Making something this large out of sil-nylon without it would be next to impossible I think.

 

The end result is a perfect copy of the "real" megamid floor, except about half the weight. Now I need to find out some way to add just a bit of grip to the bottom of it.

 

I wouldn't recommend this project unless you are expert seamstress. Maybe it's easier than I think, but it sure seemed like what she was doing was hard. She has been sewing for longer than I've been alive so it wasn't too much of a project for her!

[cracked]

Pics?

[cj001f]

The end result is a perfect copy of the "real" megamid floor, except about half the weight. Now I need to find out some way to add just a bit of grip to the bottom of it.

I'm not sure if the Mega floor has the same problem the Betamid does - that it's a bit too much of a "bathtub", unless your extra careful about keeping the sides up taught (a pain). Velcro on the edges maybe?

[marylou]

Every one of those floors I've seen has been really "bathtubby." Nothing wrong with just using a plain old groundsheet though.

 

Josh, thanks for the update. Be sure to check back in here on your progress in making the thing non-stick enough to not be totally annoying. My experience with sil floors has been that if the ground is perfectly level (yeah, right!) it's fine, but if not, then it's slip and slide city. So let us know how it all comes out.