I’m relatively new to shaping and wondering about which resins can be used with certain foam. I have access to a multitude of resins through my work place. I’m thinking about buying some from my boss instead of the local surf shop as they charge silly amounts of money.
Im using standard polyurethane foam at the moment with standard poly resin. I can get isothalic resin and vinylester resin from work to name but a few. I’m not keen on epoxy just yet.
We don’t use polyurethane foam at work so I don’t know how things will react. I don’t won’t to ruin any boards before I get some info from your collective swaylock brains.
Also, does anybody know if ‘mw’ solution and ‘wax in styrene’ are one and the same thing.
if you’re using a polyurethane blank, you have the option of using polyester resin or epoxy resin. If you’re using an eps blank you can only use epoxy resin, if you use polyester on eps it will melt your foam and you will have a massive problem on your hands. i believe with xps foam you can use both as well. I’ve never heard of anyone using vinylester to build boards before, but im sure its been done.
Both eps and xps are essentially styrofoam. One is expanded the other extruded. Two different processes with essentially the same chemistry.
The “sty” part indicates that it’s styrene based. Neither one can be used with polyester resin. Poly contains styrene and is basically a solvent. That is why it melts foam. Polyurethane foam is the only one you can safely glass with polyester resin. All others need epoxy.
Don’t forget urethane resins like Resin-X. Those can be used on all types of blanks. They tend to have a shorter pot life and most guys using it thin it with xylene which is no longer available in California. The xylene decreases the viscosity and lengthens the pot life.
MW is the same as the wax/styrene surfacing agent used in polyester hotcoats and gloss coats.
Vinylester is somewhere between epoxy and polyester in material properties.
Cheers guys… It’s a big help. I’ll delve into the properties of vinylester resin to find out if it’s better/worse than polyester resin.
Im basically shopping around trying different things to see what happens.
The isothalic resin we use is considered extremely water tight but wheather or not it melts poly foam remains to be seen, perhaps a few test pieces on scrap foam will clear things up…
Isophthalic resin is the industry standard for surfboards. It is a type of polyester resin. The other common type of poly resin is orthophthalic resin, and it’s less expensive while also less desirable. The resin you refer to is not going to melt poly foam. As already stated, styrofoam, such as EPS and XPS is the type that melts if you use the wrong resin.
“A comparison of polyester resins, reveals that isophthalic have some key advantages over orthophthalic. Isophthalic polyester resins are undoubtedly of a higher-grade and offer substantially higher strength, better flexibility and chemical resistance. To illustrate the important differences further, in laboratory tests, a fiberglass reinforced isophthalic polyester resin panel showed 10% higher flexural and 20% higher tensile properties than a comparable panel using orthophthalic polyester resin.”
keep in mind your resins most likely arent filtered for supreme clarity and will not have the UV inhibitors and all the additives that make surfboard resin… surfboard resin.
The polyester “surfboard resins” used as industry standard (Silmar 249) are derived from casting resins, reflecting the industry’s demand for a water-clear product. Real laminating resins have a much higher solids content, are slightly stronger, and bond better. Dion Iso used to be the standard back in the day, but hardly anyone uses it anymore. Costs too much and it isn’t as clear.
Polyester will never get close to the physicals of more advanced resin systems, and its heavier, which is why it’s never used in any advanced composite products.
Polyester resins, both ortho and iso, and vinylester resins contain solvent (styrene) which makes them incompatible with EPS or XPS foams. Those are used on urethanes only. Epoxy resins are solvent free so they can be used on any foam you choose.
But now the technical part, if your using a urethane foam and want to use an epoxy it must be high modulus (modulus is stiffness essentially high being stiff and low being more flexible) or the board will dent and delaminate. Polyester surfboard resins are high modulus but this makes them brittle which leads to broken boards, cracks and dings. Lowering polyester modulus through the use of plastasizers leads to denting and delamination so that no solution (I’ve tried it). Epoxy allows for higher modulus without being as brittle as polyester (some and very good even at room temperature cure). So bottom line is matching the resin system to the foam and glass schedules to get the best overall qualities is really what it’s all about.
Using eps or xps allows a broader range of modulus and uses only epoxies. Which modulus works best in your system is dependant on the other materials used. With urethane foams you pretty much have to use a polyester or a high modulus epoxy only.
Greg - is Kwik Kick a high modulus epoxy? I glassed a “green foam” urethane blank with KK and got a lot of denting…should I have used a different version of RR? (could also have been user error of course!) thanks,