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Using polyester resin with fiberglass

 
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hal davis



Joined: 28 Aug 2007
Posts: 3
Location: SE Georgia

PostPosted: Tue Aug 28, 2007 5:37 am    Post subject: Using polyester resin with fiberglass Reply with quote

Most builders I've seen on the internet discourage the use of polyester resin for glassing wooden boats, recomending epoxy instead. However, I see lummiecraft (Sp?) says it's OK. I understand that epoxy is better, but being on a budget, I just can't afford it.

So, if one was to use polyester, what things should you do and not do to get the best results possible from this admittedly inferior product?

Also what type paint can be used over cured polyester resin and how long should you allow the poyester to cure before applying paint?

Thanks,

Hal Davis
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Bruce



Joined: 26 Jun 2006
Posts: 3

PostPosted: Thu Jan 17, 2008 1:46 pm    Post subject: Reply with quote

The reason that polyester is not recomended is that it is not waterproof. It is almost waterproof, but almost is worse than not at all. Polyester will allow small amounts of moisture to migrate through it and attack the wood. The wood will not be able to dry out when removed from the water because it is covered in fiberglass. The reason that boats can be built from polyester fiberglass is because there is no wood to rot.

Epoxy is fully waterproof. If you were to use polysester then I would leave the boat in the water for no more than a day or two at a time so that the water does not have a chance to soak through the polyester at a microscopic level.

Bruce.
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rmergy



Joined: 13 Jul 2009
Posts: 1
Location: Philippines

PostPosted: Mon Jul 13, 2009 10:19 pm    Post subject: Polyester resin Reply with quote

Ther are a couple of solutions that will work for you.
Mix an epoxy resin with an apropiate thinner and coat the wood to seal it before you apply the polyester resin. There are also some epoxy 2 part primers that will do the same thing.
There is another resin that you can use called vinalester that is like 99% water proof and the cost is just a little more than polyeser.

In the end what we are talking about is the life cycle of your boat. There are many boats still afloat that were built 25 years or more ago, built with polyestr resin and glass. After building a boat with polyester resin you must use a good epoxy primer and a good euathane paint to protect it. You must also be cauious of any dings in your paint system as they will cause damage very quickly to the under wood structure. There are a numer of paint companies besides the well known one who make some excelent coatings. When I built my steel hull schooner, I used a company thati produced the paints used to coat oil rigs that went out in the Gulf. The cost was a fraction of what they sell in the yacht supply stores. Key is to shop!

What many, if not most builders do not do is to seal the interior of their hull with a good pimer to protect the wood from water. Dryrot (misnomer) is caused from water. Wood that gets wet and can not dry out will develope a micro organisum that will actually eat the fiber out of the wood.

I hope that this will help you to choose a system that will work for you.

Robert
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aldaxmoulds



Joined: 25 Oct 2010
Posts: 1

PostPosted: Mon Oct 25, 2010 5:15 pm    Post subject: Reply with quote

I use a product called Envirotex Lite to coat my wooden model boat hulls before fibreglassing them. I found the Envirotex to work well making a water tight hull.

Cheers
Joseph

http://www.aldax.com.au/techtiparticles/resincastingjewellerychesssets.htm
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Rose2



Joined: 07 Jul 2013
Posts: 1

PostPosted: Sun Jul 07, 2013 10:41 pm    Post subject: Reply with quote

I noticed the last post from zebinuk back in April in regards to his Sea Babe. However mine requires an outboard as described on the original plans. I'm not sure if he is still about at all? I have noticed this forum pretty much looks dead though but I thought id at least leave a message and try my luck.
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Rose
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