The ultimate fiberglass substitute?

[imported_Conrad]

Like most guys here, I really dislike sanding/grinding fiberglass, whether set in epoxy or polyester, but some surfaces require sheathing to stand up to the weather or abuse. And while a number of folks speak highly of Defender's Xynole and polypropylene, they cost more than glass cloth in bulk. So after walking past the fabric sold by Home Depot for the Snowroof system, I finally decided to take some home amd try it. Although I can't confirm the weight, my best guess is it's about 6-7oz./square yard, label says it's polyester, clearly a loose spun weave. The label also claims it increases the strength of the rubber roof sealant it's designed to be saturated with by 1,000 psi; all I know is that my 200lbs can't break a 4" wide piece, its got to be close to the strength of glass, or at least strong enough!

When I put some test strips on a bit of 1/4" fir ply, using epoxy, it bulked up to about the same thickness as 10oz. cloth, maybe a bit more. When cured I sanded it smooth, then cut through the ply and measured the coating thickness at just a hair over 1/16". A couple of test bits were left with corners sticking up so I could grab them for a peel test- it was a mix of torn wood fibers and cloth/epoxy. I use FGCI 1:1 epoxy, which is noticably more flexible than most other brands, and this polyester fabric seemed more flexible than glass cloth, but it's a bit of a WAG. Finally, it saturated very well with the epoxy, very even and quick, but didn't go completely clear like light weight glass well, so it won't work where you want a natural finish.

And the best part? A 50' roll, 50" wide, sells for just under $60 or about $2.40 a square yard, half the cost of the alternatives, and you don't have to mail order it, just go pick it up. I have no idea what the abrassion resistance is, but when you want to build and reinforce film thickness in an epoxy covering/coating this seems like an alternative worth considering. And it doesn't itch at all.

Check out www.snowroof.com (http://www.snowroof.com) product #CMPE-250

[ 09-21-2002, 04:55 AM: Message edited by: conrads ]

[Dave Hadfield]

Worth checking out. Thanks.

I wonder what it's like to drape over the curved surfaces of a round-bilged hull? Still, even if it doesn't conform, it would work for hard-chined hulls.

[rkrough]

I'll be damned. I used the fabric 3 weeks ago for a roof repair, never occured to me that it could possibly be used in place of Fiberglass cloth.

[Tom Lathrop]

I have an article on sheathing fabrics in the current issue of Boatbuilder magazine but did not know about the roofing reinforcement material you mentioned when I did the tests several years ago. There has been a piece of this material laying about in my shop for a while and I did do some testing a couple months ago. My results were similar to yours although I did a rough abrasion test also. I did not repeat the accurate abrasion method that was used on the other materials (because of set up time) but I think that the roofing fabric is better than glass but inferior to Xynole or Polypropylene in abrasion resistance.

Now that you have brought it up, I think I will re-create the test set up that I used before and run some objective tests on it. It does take about the same amount of resin to cover as Xynole. It does not conform to compound surfaces as well as Xynole but is better than glass in this respect.

[On Vacation]

Did the cloth satuate or just coat? There are some cheap fiberglass around that is sold that does just this leaving you with a false sense of security if relying on it as part of your structure. Did the cloth keep the color of it after saturation or turn the same color as fiberglass wetted out?

[NormMessinger]

Oyster Mike makes a most valid point. If the material is being used simply to assure an even coating of goop and perhaps to provide abrasion resistance, that's one thing. But if it is being used to reinforce joints where adhesion with the goop is part of the structural equasion, that is quite another. Not even all fiberglass is acceptible for the latter.

--Norm

[islandboy]

Five years ago I used that product on my plywood deck but rather than epoxy, I used the black goop(Elastoseal) recomended for that cloth.'Sno Roof' also makes a top coat called 'Kote-a deck' for porches and decks with nonskid mixed in.Very easy to apply,no mixing and it cost$100. for 5gal bucket.Black goop is $12/gal.and goes a long way.I used 2 gal.on 46ft.deck.I haven't had the first leak in five years and it just now needs to be topcoated again.I highly recomend these products as an alternitive to f/glassing.For me it has proven itself over the years of hard sailing and abuse.

[imported_Conrad]

In regard to saturation, the material has about the same density and feel in your hand as glass, but has a fuzzier look, not as distincly woven. When the epoxy goes on, all of the individual fibers disappear and the color of what ever you're covering comes through, but a bit of cloudyness remains. I'd guess it's doing a good job of coating the individual polyester fibers, but the fibers themselves, unlike glass, aren't clear. You could make some joints up and break them to test strength- since the stuff also comes in four inch wide rolls, it would be nice if it added enough strength for chines, etc. My first thought though was that it does a great job of ensuring a sufficient thickness and reinforcing epoxy coatings on fir ply, etc.