Fiberglassing and epoxy

[Salty Bear II]

We are currently refitting our older trawler. We are building new deck beams in a built up "glue-lam" configuration and will be putting fiberglass cloth and polyester resin over top the new deck head. Does anybody know where I can get any information on compatability of polyester resin and "System Three G2" epoxy?

[Delfin]

WEST probably has information on this, but they are perfectly compatible, in my experience. * Epoxy will stick to pretty much anything without reaction.

[C lectric]

System 3 mfgr. should be consulted for a definitve answer.
My understanding is epoxies will stick to polyester resin and do it well.
That is NOT the case in reverse though.

[Sailor of Fortune]

Get a copy of "Gougeon Brothers on Boat Construction", they are the creators of the West system and have a very comprehensive book. Almost all of the suppliers of epoxy have a free manual online also. System 3 and* Raka cruising are 2 that come to mind.


-- Edited by Sailor of Fortune on Wednesday 15th of February 2012 05:52:16 AM

[psneeld]

Salty Bear II wrote:
We are currently refitting our older trawler. We are building new deck beams in a built up "glue-lam" configuration and will be putting fiberglass cloth and polyester resin over top the new deck head. Does anybody know where I can get any information on compatability of polyester resin and "System Three G2" epoxy?

*Best to go straight to the manufacturers of the resins you are using.* The biggest deal is curing.* Unless done curing...most resins aren't compatable (going to bond well)*and painting has issues with them too when they are still in the process of curing and they still need prep before anything is put on them.

When warmer weather hits NJ...I'll be layng a new decks (already have the teak off the fly bridge) and I'll be putting* several coats and at least one layer of glass on my entire bottom before the Interprotect barrier coating system.* I'll be using all epoxy to hold everything together but may use a polyester resin just for covering the plywood on the decks.

I not worried about the poly sticking to too much as I probably will go back and filet the edges of the poly glassed ply to the vertical structures of the boat to seal/keep'em down.

As long as it all cures OK...I'm not worried about the 2 different resins or whose they are.



-- Edited by psneeld on Wednesday 15th of February 2012 06:27:01 AM


-- Edited by psneeld on Wednesday 15th of February 2012 06:28:10 AM

[skipperdude]

Just remember what C lectric said. Polyester or vinylester*will not stick to epoxy.

SD

[psneeld]

skipperdude wrote:
Just remember what C lectric said. Polyester or vinylester*will not stick to epoxy.

SD

*West system says that gel coat will and if it will...then polyester will.* I think the trick is to get the epoxy "absolutely cured", cleaned, preped and a good mechanical bond and it will work for light duty/cosmetic work...

[Datenight]

Salty Bear II wrote:
We are currently refitting our older trawler. We are building new deck beams in a built up "glue-lam" configuration and will be putting fiberglass cloth and polyester resin over top the new deck head. Does anybody know where I can get any information on compatability of polyester resin and "System Three G2" epoxy?

*Salty,

I know you asked about System Three. I can't answer that but can tell you from my experience in the same project that WEST will work.

Rob

37' Sedan

[pull]

Back in the '80's I owned the second largest contract FRP molding company in Florida.

We made hundreds of hulls and decks for dozens of boat builders - from liferaft containers to 55 ft sailboats. In the good times, when we were smoking along I was buying 10 55 gal. drums of polyester resin a week.

Good times! I sold the business decades ago.

Since then the total number of times I have used polyester resin = 0.

Boatbuilders use polyester because it works well in a E or S glass matrix laid up in a contact mold, and because it's relatively cheap.

Polyester resin is not a glue. Bonds between polyester and plywood will always fail as any Taiwanese boat owner can tell you.

My shop was temperature and humidity controlled. I cringe when I see someone guesstimating the polyester catalyst with a squeeze bottle outdoors.

Use epoxy for every part of your project. The additional cost will end up as a small item in the final bill. It will last a whole lot longer, and you'll sleep better!

This advice is worth what you paid for it, and no doubt other members will have stories about how they have used polyester successfully. Good for them, but I would not buy their boat.

Mike
Palm Coast FL.

*

[FF]

"Polyester or vinylester will not stick to epoxy."

Actually it does not stick very well to polly unless it is uncured , or very green.

THe USCG requires a polly laminate to be ground to 85% clean glass showing if more than a specific numbers of hours have passed.

SO the USCG is hoping the new polly will get enough clean glass to grab on to create the "secondary"bond.

Epoxy is far better at this , BUT be wary the hardner in most epoxies is unfriendly to skin contact.

Your allergy will build as more contact is made.