In the industry, liquid plastics, namely epoxies, polyesters, and vinylesters are used to saturate (wet out) the fibres of wood, glass, Kevlar or carbon to form a fibre reinforced plastic (FRP). To create a quality part, adhesion to the fibres is the most important factor.
|
Resin |
Polyester |
Vinylester |
Epoxy |
|
Strength of Bond |
Good |
Better |
Best |
|
Waterproof |
Good |
Better |
Best |
|
Lamination |
Good |
Better |
Best |
|
Repairs |
Better |
Good |
Best |
|
Price |
Best |
Better |
Good |
Not all resins keep their grip on fibres equally. Here’s a bit more info:-
Epoxy Resin
Epoxy resin is known in the marine industry for its incredible toughness and bonding strength.
Quality epoxy resins stick to other materials with very strong bond (2,000-p.s.i. vs. only 500-p.s.i. for vinylester and less for polyester resins). In areas that must be able to flex and strain WITH the fibres without micro-fracturing, epoxy resins offer much greater capability.
Cured epoxy tends to be very resistant to moisture absorption.
Epoxy resin will bond with already-cured materials, which makes repair work easy, reliable and strong. It actually bonds to all sorts of fibres very well – so if using other skins than fibreglass it would be the preferred choice.
Cores: Epoxy can be used on PU, EPS and XPS cores
Safety: Use protective clothing and ventilated mask
Clean: Clean up with Acetone or for the more health and eco conscience use white vinegar
Vinylester Resin
Vinylester resins are a compromise between the low cost polyester and epoxy resins, it utilises a polyester resin type of cross-linking molecules in the bonding process.
Vinylester is a hybrid form of polyester resin which has been toughened with epoxy molecules within the main molecular structure. It offers a better resistance to moisture absorption than polyester resins but its downside is in the use of liquid styrene to thin it out (not good to breath that stuff) and its sensitivity to atmospheric moisture and temperature.
Sometimes it won't cure if the atmospheric conditions are not right. It also has difficulty in bonding dissimilar and already-cured materials. Due to the touchy nature of vinylester resin, careful surface preparation is necessary if reasonable adhesion is desired for any repair work.
It is also known that vinylester resins bond very well to fibreglass, but offer a poor bond to Kevlar and carbon fibres.
Cores: Can be used with PU cores
Safety: Use protective clothing and ventilated mask.
Clean: Clean up with Acetone
Polyester Resin
Polyester resin is the most cost effective resin available in the marine industry and offers the least adhesion, has the highest water absorption, has high shrinkage and high VOC's.
Polyester resin is mainly compatible with fibreglass fibres (though has been tried with other skins with some success) and is best suited to building things that are not weight sensitive.
It is also fractures easily, though for surfboard making this is the preferred resin as it keeps the cost down and easy to use with measurements not needing to be so accurate as vinylester and epoxy resins
Cores: Polyester resin can’t be used with EPS and XPS cores as it will react with the styrene and eat into the surfboard blank
Safety: Use protective clothing and ventilated mask
Clean: Clean up with Acetone
What’s new?
Bio-resin is quite new on the market, so the performance is still being developed and improved. It’s an epoxy resin that has been 55% derived from natural, renewable resources such as pine waste and vegetable oils.
Shapes and Design - the fun part
Check out the new Surfset Resin