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Old 27-05-2015, 11:26   #1
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Epoxy / Fiberglass Glass Marine Ply sheathing help

Hi
I am currently 3/4 finished building a 11M catamaran, and looking for a supplier of 200gsm woven cloth and epoxy to sheath the hulls, decks etc.
I am having a problem with the woven cloth peeling away from the epoxy as described in the article written on the Glen L marine website
It appears as thought the glass has the incorrect "sizing" chemical , when pulling on the glass cloth it is peeling from the plywood and leaving the glass fabric imprint behind on the epoxy covered plywood i.e. no adhesion between cloth and epoxy This seems to be a cloth problem. as 4 different epoxy test have revealed the same results
any information and comment, and the name of a respected supplier, would be greatly appreciated
I have now run out of suppliers here in my part of the world that can help me solve the problem
thanks in advance
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Old 27-05-2015, 11:37   #2
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Re: Epoxy / Fiberglass Glass Marine Ply sheathing help

Do some research on fiberglass sizing compatability with epoxy. I don't recall the details, it's been a while since I did this, but there are recommended sizings for use with epoxy. You will find this on the web.
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Old 27-05-2015, 11:47   #3
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Re: Epoxy / Fiberglass Glass Marine Ply sheathing help

Thank you very much for your reply, I have done this already, and have dicovered that the sizing agent is a product called "silan" and have asked the supplier for data sheets confirmig this. But it appears all "silan" coated cloth is not equal. I think I am being supplied with a product imported from china or some other manufacturing country.
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Old 27-05-2015, 15:37   #4
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Re: Epoxy / Fiberglass Glass Marine Ply sheathing help

I get my cloth here:
Shipping / COMBINED SHIPPING
and I use West System epoxy. Cheaper epoxies seem to do a cheaper job. I have never had your problem. I used to have a marine building/repair business. Now I only do my own decks. I usually start with 2.0 rsm so I have a thicker base and then add other weaves as needed. I never use polyester resin.
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Old 28-05-2015, 09:15   #5
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Re: Epoxy / Fiberglass Glass Marine Ply sheathing help

You might try mechanically fastening the glass to the ply every three inches or so with Monel staples to keep the material from creeping.There is a very good book " Covering wood hulls with fiberglass" by the guy who covered down east lobster boats with the first good results.I can't remember what his name was. Many of us remember the early attempts with fiberglass sheathing pulling off, taking chunks of wood with it. This guy solved the problem. Maybe his name was Mate'.
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Old 28-05-2015, 09:18   #6
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Re: Epoxy / Fiberglass Glass Marine Ply sheathing help

I've used Fiberglass Coatings products for about 20 years. I started using them because they're local so I can go down there & talk to people in person. Good prices & I've had good results.
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Old 28-05-2015, 09:49   #7
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Re: Epoxy / Fiberglass Glass Marine Ply sheathing help

Contact a manufacturer - you get lots of good advice and be pointed in the right direction for a local supplier!
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Old 28-05-2015, 10:22   #8
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Re: Epoxy / Fiberglass Glass Marine Ply sheathing help

The book you mentioned I think is " The Fiberglass Boat Repair Manual" By Allan Vaitses.. Great book by an Old Man of the Sea !!! He also wrote a boat on Sheathing wood boats with fiberglass.
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Old 28-05-2015, 10:29   #9
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Re: Epoxy / Fiberglass Glass Marine Ply sheathing help

I've used System Three since it saved over West. Good results. Are you sure you aren't having an application problem?
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Old 28-05-2015, 10:33   #10
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Re: Epoxy / Fiberglass Glass Marine Ply sheathing help

I get my glass from Jamestown Distributors. It's designed for epoxy. Sounds like you're using fabric designed for polyester resin. Poly has a wetting agent on the cloth, epoxy generally doesn't. With a full wet out, and a cure of 24 hours, you shouldn't be able to pull off the fabric by hand. After 5 days, it should be fully bonded.
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Old 28-05-2015, 10:43   #11
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Re: Epoxy / Fiberglass Glass Marine Ply sheathing help

Delcrest - is your cloth wet? or even damp? even excess moisture can cause wet-out issues which sounds like what you have. You do not say where you are located but you need to keep your cloth dry. You should notice a color change as you "wet-out" the cloth with epoxy. If it stays a bright white color, then you have a problem. I have seen this with "old" cloth/mat. I assume you are rolling out any air. when you peel off the cloth, is it still flexible or almost rigid?
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Old 28-05-2015, 10:55   #12
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Re: Epoxy / Fiberglass Glass Marine Ply sheathing help

I always do a dry layup, i.e. put the fiberglass cloth on the plywood, then pour the mixed epoxy resin + hardener on the center and use a plastic spreader to work the resin further out towards the sides. The fiberglass should turn transparant very quickly while doing this. Here are some pictures:

the moment we pour the mixed epoxy in the center:


finished spreading it out:


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Old 28-05-2015, 11:19   #13
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Re: Epoxy / Fiberglass Glass Marine Ply sheathing help

Hey Delcrest,
I also ran into a few hiccups when building a woods ply cat. I can't see the glass being the problem though. One issue I had was that the epoxy did not kick off well as I was building in winter and the ambient temp was a little low. The result was that surface of the set epoxy was left with a kind of film on it, which I had to remove so that the next layer of glass would bond properly. Not sure what sort of conditions you are building in, but the temp is rather critical when working with epoxy. The reaction between the two parts is exothermic i.e. it generates heat to set it off. You can try leaving the mixture in the pot for a little longer.- you'll feel the pot start to warm up. If you apply it too soon it does not kick off well as it will be a thin layer spread out and cooling.
Do a little at a time to test your timing because you can end up with a pot of syrup if you leave it too long.
Don't apply the glass directly to the ply with your first coat. First saturate the ply with a layer of epoxy. Once it has cured give the surface a light rub with some coarse sandpaper to give it a mechanical edge for the next layer "grip" onto.
I used a woven roving glass which was not woven too tight, so it was easy to "wet out". The glass needs to be thoroughly wetted out and then you can use a squeegee to scrape over it, so that all the air is pressed out, leaving your lay up tight like a tiger.
Keep us updated as to how you're getting along.
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Old 28-05-2015, 11:46   #14
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Re: Epoxy / Fiberglass Glass Marine Ply sheathing help

Quote:
Originally Posted by Craig Cape Town View Post
Hey Delcrest,
I also ran into a few hiccups when building a woods ply cat. I can't see the glass being the problem though. One issue I had was that the epoxy did not kick off well as I was building in winter and the ambient temp was a little low. The result was that surface of the set epoxy was left with a kind of film on it, which I had to remove so that the next layer of glass would bond properly. Not sure what sort of conditions you are building in, but the temp is rather critical when working with epoxy. The reaction between the two parts is exothermic i.e. it generates heat to set it off. You can try leaving the mixture in the pot for a little longer.- you'll feel the pot start to warm up. If you apply it too soon it does not kick off well as it will be a thin layer spread out and cooling.
Do a little at a time to test your timing because you can end up with a pot of syrup if you leave it too long.
Don't apply the glass directly to the ply with your first coat. First saturate the ply with a layer of epoxy. Once it has cured give the surface a light rub with some coarse sandpaper to give it a mechanical edge for the next layer "grip" onto.
I used a woven roving glass which was not woven too tight, so it was easy to "wet out". The glass needs to be thoroughly wetted out and then you can use a squeegee to scrape over it, so that all the air is pressed out, leaving your lay up tight like a tiger.
Keep us updated as to how you're getting along.
I agree with sanding for tooth if the coat has set.But your best bet with epoxy is to get the glass on quickly to get the chemical bond, still a tad tacky. Actually the same with polyester. Sometimes you need to sand if a large area. Ambient temp as previously said is very important as is dry glass be it CSM, roving or cloth. Laying a piece of glass out in the hot sun works if it is questionable. JMHO
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Old 28-05-2015, 13:55   #15
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Unhappy Re: Epoxy / Fiberglass Glass Marine Ply sheathing help

Thank you for all your replays, the main suppliers , the designer are all baffled I have now sent the 10 different test pieces that have all failed using three different manufactures cloth with 4 different epoxy 3 0f the epoxy from the same supplier to indendent n testing laboratory
I have the data specification of all the glass and the sizeing is correct,
I am using the wet on wet system, applying Peelply
A squeegee to firmly smooth out the peel ply making sure there is no dry areas and the excess epoxy removed to the scrap container
The complete test pieces left for a week,at atemperature of between 20 to 38 degrees centigrade
The laminate looks perfect...but by carefully lifting the overhanging cloth from the edge of the plywood the glass starts to lift and pices of glass can be removed easily you thumb and forefinger for up two hundred millimeters leaving a perfect imprint of the glass weave on the epoxy covered ply wood
As described in the Glen indendent sent all epoxy and clothnand plwood to composite testing laboratory and await the results...
This "delamination" was only discoverd by accident When a friend tried pulling the glass from the test pieces
Now trying a differen epoxy supplier completely and will post my findings once more test are done
Makes you wonder how many boats are out there with bad adhesion between glass and epoxy...epoxy to plywood / bulkheads is perfect
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