West Sys Epoxy over old polyester fiberglass = problem?

[portsample]

Hey all- I'm doing some work on the cabin roof of my boat. The previous owner had laid a layer of fine mesh fiberglass cloth in polyester resin (30yrs ago) on top of the cabin replacing the old painted canvas. One corner of this has let go of the wood, however the bond looks good for the remainder of the surface.

Question: Can I apply West System Epoxy in contact with this old fiberglass without having problems?

TIA for the usual wisdom.

[holzbt]

Yes. Epoxy will adhere to polyester.

[AstoriaDave]

Likely the rest is ready to go; polyester resin is not an adhesive. When you scrape that corner down, see what happens when you stick the scraper under the edge of the resin/cloth -- does it lift it? If so, the prudent thing to do is to remove all of it and replace it with epoxy/glass.

[ccx2]

And you will have to paint the epoxy to protect it from UV Degrade .

[JimConlin]

Sand it vigorously.

[SchoonerRat]

Epoxy will stick to the polyester better than polyester will. The problem is, the epoxy will not improve the poly's original bond to your deck. If the glass is coming loose, epoxy will not help.

[paul oman]

from personal experience and from comments from customers, polyester/fiberglass bonds to wood surfaces tend to dis-bond in 7-10 years. You might consider something a bit for flexible than the epoxy you're suggesting to allow for expansion/contraction of the misc products under it.

[Scott Rosen]

I had a similar situation. It takes some guts, but grab a loose corner of the polyester and glass and peel back hard. You'll probably take a fair amount of it off in a sheet.

Bite the bullet. Peel off the old. Sand it to bare wood. Fair it well. Seal it with epoxy. Cover it with dynel or xynole fabric set in epoxy. Paint with a two-part LPU.