quick poly resin over ply question

silveraire

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I am making a new seat box for a craigslist find lounger seat that had no base. I have the box made with 3/4 reg ply. Can I just sand and then brush on few coats of poly on it to waterproof, then cover in vinyl? No cloth involved. I was given some poly, thats why I've asked. I have heard of bonding issues with ply and poly. I Don't see the need for epoxy for a seat box, as long as poly will bond well.

ty,
chad
 

Woodonglass

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Re: quick poly resin over ply question

Poly without mat is like a Lake with No Water. Just won't work. It will Crack and Fail. Epoxy has BINDERS in the Resin Poly does not. It needs the mat to hold everything together.;)
 

silveraire

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Re: quick poly resin over ply question

so much for my free poly. lol. Whats best to waterproof ply that will be covered with vinyl? Should I just go out and buy some epoxy?

chad
 

Woodonglass

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Re: quick poly resin over ply question

I would use 5 min epoxy to seal the edges and then give it several coats of Exerior Grade Polyurethane. Or if available Epoxy.
 

silveraire

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Re: quick poly resin over ply question

ty wood. will do. As always, ty for the help.

chad
 

ezmobee

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Re: quick poly resin over ply question

Chad, I don't think CSM (chopped strand mat) is that expensive and adding that to the equation will turn your now worthless poly into the ideal waterproofing scenario.
 

Cadwelder

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Re: quick poly resin over ply question

Chad, I don't think CSM (chopped strand mat) is that expensive and adding that to the equation will turn your now worthless poly into the ideal waterproofing scenario.

This is correct, if I read correctly you have some free polyester resin?? As long as it's fresh resin then by all means just pick up some CSM, you'll get a better job that way. EZ is correct on the price...CSM is about the cheapest glass there is....
 

Mur386

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Re: quick poly resin over ply question

Yes adding fiberglass will help somewhat, however the polyester resin will not adhere very well to the wood, for that you need epoxy, I reccomend West System epoxy for what your working on. It adheres to wood, otherwise your just making a poorly attached shell with the glass cloth around your project using the polyester resin.
 

Woodonglass

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Re: quick poly resin over ply question

Yes adding fiberglass will help somewhat, however the polyester resin will not adhere very well to the wood, for that you need epoxy, I reccomend West System epoxy for what your working on. It adheres to wood, otherwise your just making a poorly attached shell with the glass cloth around your project using the polyester resin.

Not quite sure where you got your information but Polyester resin adheres quite well to wood especially with fiberglass mat. Epoxy IS inherently stronger than poly and DOES waterproof better but saying that Poly does not adhere to wood well is NOT a correct statement.
 

Cadwelder

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Re: quick poly resin over ply question

Yes adding fiberglass will help somewhat, however the polyester resin will not adhere very well to the wood, for that you need epoxy, I reccomend West System epoxy for what your working on. It adheres to wood, otherwise your just making a poorly attached shell with the glass cloth around your project using the polyester resin.

This simply isn't correct....polyester resin has been adhering to plywood for years...95% of boats are made that way. (or were, I know many are using all composites now)

Sorry, Woody I know you already said this, but I just couldn't leave it alone.
 
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