ground sheet

[victoria maki]

looking for a light weight ground sheet. it is blue with threads running through it. can be cut to size without ruining it. i saw someone using one, but can't remember where he said he got it. i thought it was gossemar gear, but the one i ordered was a sheet of light wt. plastic. anyone out there know what i am talking about???

[Carter Hunt]

Maybe someone else can confirm this, but I believe you are thinking of the Gossamer Gear Spin Sheet. It comes in white or blue and is $25.

[Scott Bentz]

What you got from Gossamer Gear is a Polycro groundsheet. I like those and they hold up quite well. I have not used a spinn sheet.

[Michael Davis]

Scott,

How would you compare Polycro for puncture resistance to 1.1 oz silnylon or Tyvek homewrap or any other material that you have compared?

[Vick Hines]

Mad777,
Polycro is waterproof. Tyvek is not. However, Tyvek is water resistant, more puncture resistant than Polycro, durable and lies flat easier than the (pardon) gossomer-thin Polycro. 1.1 (1.35) oz sylnylon is not waterproof, either, but it has a higher head than Tyvek. I'm not sure about comparative puncture resistance. I have used Polycro and find it tedious to use compared to either Tyvek of sylnylon.

BTW, my favorite silnylon is the double coated type which has a head comparable to polyurethane. It is supposed to weigh more than the simple silicone impregnated nylon, but my scales don't show as much difference as the manufacturers report – 1.4 oz v. 1.6 oz.

Victoria,
Are you sure you are not talking about fiber-reinforced vynil? The Krinkly stuff available in blue at any hardware store?

[victoria maki]

vick, the guy who had it said he got it from a web site and i did not look like something from a hardware store. i am starting to think that it is the gossemar gear spinsheet. it did not say they had it in blue, so was alittle confussed..thanks to everyone who posted….vicky

[Rod Lawlor]

Vick,

Do you know of an on-line supplier for the double coated sil-nylon? That sounds like what I'm looking for, for a Megamid floor.

Thanks, Rod

[Jim Colten]

Do you know of an on-line supplier for the double coated sil-nylon?

If you don't find a commercial source, this MYOG article might get you what you want.

[Roleigh Martin]

Vicky, go to this page

http://www.gossamergear.com/cgi-bin/gossamergear/spinn_sheet_ground_cloth.html

You can use the drop down to choose blue.
Spinnsheet™ Ground Cloths

They used to sell a single width size but no longer, only double. You said you tried Gossamer Gear, did you try this sheet of their or their lighter, but more fragile, PolyMicro sheet?

[Vick Hines]

Rod,
Double coated silnylon:
http://www.americanhomeandhabitat.com/products/Silk-iene%20Silicone%20Coated%20Nylon%20Ripstop.htm

You can occasionally find if from Outdoor Wilderness Fabrics and Trhu-hiker. Be sure to bug them about it.

[Michael Davis]

I might be wrong in my assumption here but, the "double" coated silnylon from American Home & Habitat, sounds like typical silnylon. I say this because I have always been under the impression that plain ole silnylon was coated on both sides anyway. But maybe, my assumption is incorrect. Can anyone confirm what the coating process is for "normal" silnylon?

[Jason Brinkman]

I would like to know this too. Some of the silnylon I have worked with seems to have a shiny side, but not all. Not sure if that's from the weave, the coating, both, or neither.

[Roger Caffin]

Very brief lesson follows.

PU-coated fabric has a film of poyurethane spread out on one surface. It is important to note that the film does NOT penetrate the fabric. The coating sits on top of the fabric and can be delaminated.

"Silnylon" is light parachute nylon fabric which has been coated on both sides with a fairly liquid silicone polymer. The liquid polymer does wet the fabric, and the result is that the silicone goes right through the fabric. It is called 'coated' because that is the process used, but you would do much better thinking of silnylon as a 'fabric reinforced silicone polymer sheet'.

As far as I can see, the silnylon sold by AHH has the same source as that sold by OWFINC and several other DIY distributors. And it is quite different from the various 'spinn' fabrics around.

This is different from the fabric used by some gear makers which has a PU coating on one side and a silicone coating on the other side. As far as I can see, the ONLY reason for having a PU coating on one side is so the gear manufacturers can tape-seal the seams on the PU side.

Cheers

[Michael Davis]

Thanks Roger, always good to know what we are dealing with.

[Seth Ayotte]

Thanks for the link Jim. This looks like a reasonable solution to the main drawbacks of conventional silnylon floors. I may give it a try.

Seth

[Rod Lawlor]

Roger,

What about a higher hydrostatic head? I would have thought that this would be a decent reason to use PU coated silnylon on a tent floor. The silnylon limits water absorbence (is that a word?) of the fabric, the PU prevents water absorbance (it should be) of my pants or more importantly, my kids pants, when they sit down in the tent.

Rod

[Roger Caffin]

Hi Rod

> What about a higher hydrostatic head?
I have two different sorts of silnylon: the old wet-look and the new dry-look.
The wet-look has a very high hydrostatic head but went out of production because of manufacturing problems. The silicone formulation was changed to the dry-look version. Unfortunately, the modern dry-look version has a lower hydrostatic head.

I was using the dry-look version for the floors of my tents. After several years of use in Australia and then several months continuous use in France the floor started to leak slightly when the tent was kinda floating. It bucketed down that night!

So I grabbed a couple of tubes of bathroom silicone sealant from a hardware store in Courmeyer, spread the tent out upside down, and smeared silicone sealant across the underside of the floor as thin as I could make it. I added a couple of ounces weight to the tent of course, but the floor is now waterproof again!

What this tells me is that you could get almost any hydrostatic head you want with silnylon just by adding a little extra silicone sealant to one surface of the fabric. There are regular references to this on the Forum. If you google around you will find "A Treatment for Silnylon Floors" By Jim Wood – an excellent reference.

Anyhow, I haven't been able to find a source for the silicone/PU fabric yet … help!

Cheers

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