Q&A Epoxy Resin vs Polyester Resin for Wood

Should one fibreglass using epoxy or polyester resin over wood.  In this case it was to join the plywood panels of a stitch and glue boat.

First, Woven fabric will give a smoother finish than chopped strand matt and is much stronger for the same weight.  It also requires less filling of the weave to get a smooth surface.

If you want the boat to last a long time I would be using epoxy rather than polyester.

The polyester relies on going a little way up the cellulose tubes and hardens. Just sort of tangles up.

The epoxy tangles up the same way but ALSO joins onto the molecular structure – much stronger.  It actually joins onto the molecular structure of the cellulose (hydroxyl bond) which polyester doesn’t.

One of the sad moments in my boat repairing life was after I had used polyester resin to fibreglass a boat’s deck.  The owner came down the day after the ‘glass had been resined and said it looked nice.  He then noticed a thread hanging out the edge and gave it an unconscious pull.  Half a metre of the cured surface tore off.  Back to the drawing board!

Epoxy IS more expensive but does a much more permanent job. But if you just want the boat for a couple of years and then are happy to throw it away polyester will probably be OK and will save you money.

Sometimes polyester does stick OK to wood, but it is not reliable.

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On the "round Australia trip" I found myself employed by a tiny business in Adelaide - Duck Flat Wooden Boats in Adelaide.It was an eye opener - It became clear that one could build a boat for a fraction of the cost of current racing boats.My ideas hinged around high performance, easy building, fun to sail and reasonably cheapToday Storer Boats are built in all countries and we have active groups on Facebook for the following groupsGoat Island Skiff Open Goose Storer Boat plans Really Simple Sails