Epoxy and Polyester Fiberglass

[triumph34]

My uncle and I are completely redoing the deck and cabin of our 34' fishing vessel. I have heard back and forth arguments about whether or not Epoxy resin is absolutely necessary.

What are the major advantages to Epoxy resin and is it necessary to spend the extra $60/gallon over to Polyester Resin.

Thanks for all the help.

[marshmat]

Hi Triumph,

If you are doing only fibreglass work (no glass-on-wood), are only working on above-the-waterline stuff, and have well controlled working conditions (enclosed shop with temperature control), some money can sometimes be saved by using polyester resins.

If there is wood involved, if there are below-waterline repairs involved, if you need the repairs to adhere to existing structure, or if you can't maintain good control over working conditions, polyester is likely to lead to problems.

Epoxy is stronger, adheres better to existing substrates, more waterproof, and easier to use. It should be the default choice for repair and one-off work unless a compelling case can be made for using a "cheaper" resin. (Just because poly is cheap per gallon doesn't mean it saves much money on the overall repair, especially when you consider the cost of scraping off and redoing a failed section.)

Although I like to concur with Matt, I would NEVER recommend Poly on repairs, it is just a waste of time and money.
Go for the cheapest epoxy you can find, which is never a difference of 60$ per gallon. Do´nt let you talk into "quality" resin. There is no difference in the "glueing" properties for a repair job.


Regards
Richard

[old_sailor]

I fully agree with apex1. If you look on-line you can find generic epoxies for about $30/gal. (at least when I looked about 3 months ago). There are different properties of the various epoxies, but unless you are looking for something specific (low viscosity, high viscosity, special cure times etc) the generic (usually 2:1) epoxies work very well for any repair work. I would suggest generic filler material such as aerocil or equivelent to make epoxy putty which will prove very handy for a lot of repair work. If you need to fair something that is above the waterline you can also add microballoons which will make it easier to sand but is not good for any structural adhesion.
Ethan

[triumph34]

I may need to be a bit more clear. We are not repairing anything. We are completely removing the deck, rebuilding, laying all new wood, and then fiberglassing in the entire structure. In that case, we will not be repairing anything, but completely building everything from new. Thanks again for the suggestions though.

[triumph34]

And if anyone can provide a web address to get Epoxy resin for less than $100 a gallon I would greatly appreciate it. I can't find it for less than that.

Originally Posted by triumph34

And if anyone can provide a web address to get Epoxy resin for less than $100 a gallon I would greatly appreciate it. I can't find it for less than that.

Wait, someone will chime in. Or use the PM function to contact the old sailor poster above. I cannot assist here from Europe (we get it at 10€ per Kg here, good quality).
When there is wood part of your construction you can definetily NOT use polyester, it will loose contact with the wood in nearly no time! It is as it is, poly is for glass laminate in a newbuild only.

Good luck!

[PAR]

Google "epoxy" and at least a dozen formulators will turn up. Even at full retail, West System is less then $100 a gallon, so you're just not looking . . .

[marshmat]

Triumph,

You mention "laying all new wood".

If there is wood involved, polyester is really not a viable option. It is just too difficult to get poly to bond reliably to wood. Polyester resin is designed for cheaply laminating pure fibreglass- nothing else.

West System (easy to use and with good technical support) is usually around $80-$95 USD per US gallon (although it's often 50% more expensive at some small-volume stores). That stuff is pretty much the cream of the crop; generic/industrial epoxies (chemically almost identical, but without the marine-dedicated research lab backing it) are often available for quite a bit less. But it takes some digging around the Web, and acting like a small industrial client rather than an amateur.

[old_sailor]

Try
Fiberglass Coatings Inc. in St. Petersburg Fl.
It is not easy to locate these suppliers. I usually found suppliers that provided bulk products to larg manufacturers of fiberglass products. They either would sell to me on a retail basis, or tell me where to buy the stuff. It will take some searching and calling. About a year ago I was able to buy a three gallon kit from Fiberglass coatings for about $125. The prices have skyrocketed recently.

[PAR]

http://boatbuildercentral.com/products.php?cat=41

Tell Joel PAR sent you . . .

[marshmat]

If that stuff works, PAR, it's a heck of a lot cheaper than what one can find in the chandleries and glass shops around here.... I've bookmarked the link for next time I need a batch, thanks

[PAR]

It works well and is blush free, unless you do your epoxying in the rain. This isn't the cheapest going either folks.

[aboyd]

Check out www.uscomposites.com $65 for a gallon of resin and a half gallon of hardener

[PAR]

Bateau's epoxy is $65 a gallon as well and the speeds are all 2:1. If you buy a 3 or 6 gallon kit it's $52 a gallon, with the next price break at 15 gallons ($49).

Where as US Composites is $65 per gallon, $60 if a 2 gallon kit, $54 if a 5 gallon kit, $50 if 10 gallons.