Epoxy over Fiberglass

I've got a 20' fiberglass boat that had wooden decks with fiberglass over them. I have since ripped out most of the flooring since water got under the fiberglass matting and waterlogged the wood. Question. I'd like to first saturate the new decking with epoxy resin then install fiberglass over the epoxy once it is dry. Can I do that? Will the epoxy and fiberglass be compatible together? Thanks.

Re: Epoxy over Fiberglass

hi......welcome to i boats........boat university.

yes if you use a cloth product....not a chopped strand product.

have you done a core sample on the foam and stringers to determine their condition?

Re: Epoxy over Fiberglass

Question. I'd like to first saturate the new decking with epoxy resin then install fiberglass over the epoxy once it is dry. Can I do that? Will the epoxy and fiberglass be compatible together?

Click to expand...

Ayuh,.... You're confusing the Terms,...

Fiberglass is Glass fibers used with various Resins....

Epoxy is but 1 of those various Resins....

Vinylester,+ Polyester are the Others......

So,.... What's your Question,..??

Re: Epoxy over Fiberglass

Having built some boats in my "youth". This is how I was taught to do it by a guy who knows what he's talking about.

I used thinned epoxy resin and coated all the wood with 2 thinned coats (really thin so it soaks into the wood) and then a standard mix with fiberglass cloth.

Make certain you pay very close attention to the edges as that's where water usually gets in... also round off the edges so that the glass with get proper adhesion. Glass will not lay down properly on square corners and you'll get voids.

After that you can fair it and gel coat it or just hit it with some 220 grit paper and paint it.

Polyester resin will also work and most boat makers use it as it's far less expensive.

I always chose epoxy as it penetrates better and provides a stronger bond.

But those little boats were built for my use, not for re-sale.

Re: Epoxy over Fiberglass

Thanks for the replies. For the secod reply, I think I was talking about polyester resin over the top of epoxy resin, but it sounds like I can just go epoxy all the way. I was just a little concerned when I went to make lap joints to join it up to the existing fiberglass (polyester) surfaces. I haven't done any tests on the stringers as I was just considering them to be ok. Something else to think about.

Re: Epoxy over Fiberglass

I'm sure someone will correct me if I'm wrong but I believe there's an issue with trying to use poly over epoxy... not the other way around IF you remove the "wax" that will form on the top of poly if you used thixotropic resin instead of laminating resin.

Most big box stores only sell the kind with the wax in it as it's usually a one coat deal.

Re: Epoxy over Fiberglass

Although Epoxy will stick to polyester, the reverse is NOT true. I would suggest you stick to epoxy for this application as you will get a much stronger bond to the wood. Many epoxies produce an amine blush on the surface as a byproduct of curing. this amine which is water soluble, must be cleaned off prior to a second coat. Working with this stuff is not rocket science but a little knowledge goes a long way. Check out the "West System" web site for all the information you need.

Dirt People Scare Me

Re: Epoxy over Fiberglass

homeradam said:

Thanks for the replies. For the secod reply, I think I was talking about polyester resin over the top of epoxy resin, but it sounds like I can just go epoxy all the way. I was just a little concerned when I went to make lap joints to join it up to the existing fiberglass (polyester) surfaces. I haven't done any tests on the stringers as I was just considering them to be ok. Something else to think about.

Click to expand...

you seem to be getting more confused by the minit....

slow down here or your gonna make a mistake.

there are different kinds of resin as bondo said in post #2.

i would highly suggest you do some reading here before you do anything else....if you but down a new deck over bad stringers and foam....youve just waisted your time.

this is a big read....but when you are done....you will know what you need to know about glassing and boat building. i suggest you read every post till the boat is moved to a different shop.........then after that....a little farther on there is detailed info on how to glass and install a deck.

http://forums.iboats.com/showthread.php?t=234392

you aboilutly MUST investigate the stringers and the foam before you put the deck down or you will be waisting your time.

Re: Epoxy over Fiberglass

this is a big read....but when you are done....you will know what you need to know about glassing and boat building.

Click to expand...

Ayuh,... I'd say you'll know Way More than any 2 people need to know....

Homeradam,...
Before you spend a Penny on supplies,+ materials,....
Spend a Day searching these archives,...
The Day spent, will pay for itself a Million times over....

Especially if you're doing an Heirloom Quality restoration for yourself, that you intend to Keep,+ put Many, Many hours on...
But,..
If you're just trying to get 1 more lap out of a Junker that's headed for the landfill in a year or less,...
You're already Over-engineering it,+ Wasting good Gas Money...

Listen to Professor Oops,.... He'll steer ya in the Right direction.......

Re: Epoxy over Fiberglass

Epoxy bonds better mechanically to properly prepaired polyester than polyester and its wood sealing properties are far better than polyester but you can not apply polyester resin over it or gel coat over it. West System claims you can if a certain one of their hardners is used but I've tried it with out any luck and most other liturature says that you can not. If you have a good dividing point, like you do (below the sole and above the sole), and you want to use epoxy for its sealing qualities, use it on the bottom of the sole and all the below sole repairs including adhearing the sole to the stringers. Then use polyester on top of and above the sole and to tie the sole into the sides and gel coat it. If you use epoxy on top of the sole you will have to paint it (you have to coat it because epoxy is not UV stable) and gel coat is much more durable than paint.