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Thread: eps/epoxy??

  1. #1
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    eps/epoxy??

    Im confused on wether my board is epoxy or PU... I have a used penetrator kustom that i bought in the winter, i didnt ask at the time because it looked like a normal board. but now that i think of it. The board is extremely light and strong but looks like a pu board... Is there a way i can find out

  2. #2
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    Its probably an EPS epoxy. From what I understand, that is like an epoxy resin coating over an old school PU blank... I think... Thats weird though, Epoxy is still a big buzz word, so im surpirsed that whoever sold you the board wasn't touting the fact that is was EPS epoxy....

    My shaper made me an EPS/Epoxy, and i went into his shop step by step and watched him. He said the heat etc was tricky. He was smoothing out some bubbles on another board... But long story short, it looked like he used his normal Clark blanks (before they all ran out)... So, it is probably a board with just the epoxy resin on it. Again, im not sure if its just old PU blanks under them, but my shaper also said that epoxy resin eats through PU... so who knows...

    Im sure one of the many shapers on here will chime and in straighten things out... But sounds to me like you haev an EPS epoxy...

  3. #3
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    Epoxy resin is used on both polyurethane (PU) and Polystyrene (EPS, XPS, XTR) foam. Polyester resin (PE) can only be used on PU foam. The styrene in PE resin "melts" EPS and other polystyrene foams.

    A good glass job with a sanded finish, when sanded properly, will make it hard to distinguish epoxy from PE. The difference in weight will come from the core... PU is much heavier than EPS. EPS has to be shaped carefully, and most likely spackled or sealed in order to get a perfect tint job. So if its tinted, it's most likely PU. EPS is generally painted, so if it looks like paint instead of resin tint, and it's markedly lighter and stronger than a typical PU/PE, it's likely EPS/epoxy.

    If you have an open ding, and it looks like bead foam, it's EPS. If it's closed cell, beadless foam, it's PU. In either case, you can always repair with epoxy.

    Also... many EPS/epoxy boards will say "epoxy" on them somewhere.
    Last edited by LBCrew; Jun 28, 2010 at 12:28 AM.

  4. #4
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    Quote Originally Posted by LBCrew View Post
    Epoxy resin is used on both polyurethane (PU) and Polystyrene (EPS, XPS, XTR) foam. Polyester resin (PE) can only be used on PU foam. The styrene in PE resin "melts" EPS and other polystyrene foams.

    A good glass job with a sanded finish, when sanded properly, will make it hard to distinguish epoxy from PE. The difference in weight will come from the core... PU is much heavier than EPS. EPS has to be shaped carefully, and most likely spackled or sealed in order to get a perfect tint job. So if its tinted, it's most likely PU. EPS is generally painted, so if it looks like paint instead of resin tint, and it's markedly lighter and stronger than a typical PU/PE, it's likely EPS/epoxy.

    If you have an open ding, and it looks like bead foam, it's EPS. If it's closed cell, beadless foam, it's PU. In either case, you can always repair with epoxy.

    Also... many EPS/epoxy boards will say "epoxy" on them somewhere.
    its wierd. im pretty sure the foam isnt eps. Its not painted or tinted, i can see straight into the foam... So i think its PU foam with epoxy resin...

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    What kind of board is it? Most board builders don't use epoxy over PU because it's so expensive compared to PE. I'd ask whoever you bought it off of and see if they know. It's only an issue if you need a repair done, but you can always default to epoxy if you have to.

    You could always polish it and see that way, too. Epoxy will not polish out well. PE will polish up to a brilliant, glossy, mirror shine.

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    Quote Originally Posted by mexsurfer View Post
    its wierd. im pretty sure the foam isnt eps. Its not painted or tinted, i can see straight into the foam... So i think its PU foam with epoxy resin...
    If you can see the foam and it has the same look as what a foam cooler is made of - it's epoxy. If its really small cell foam than mosy likely it's old school PU foam. I've never seen an epoxy board that its foam did not look like an average white cooler. You can't have a PU Board with epoxy resin - it will turn it into liquid.

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    Quote Originally Posted by Recycled Surfer View Post
    If you can see the foam and it has the same look as what a foam cooler is made of - it's epoxy. If its really small cell foam than mosy likely it's old school PU foam. I've never seen an epoxy board that its foam did not look like an average white cooler. You can't have a PU Board with epoxy resin - it will turn it into liquid.
    Sorry to nitpick but You can definitely glass epoxy resin over a PU blank. It will just negate the lightness that you could achieve with eps foam. The reason why an eps/epoxy board can be stronger (besides the resin itself) is because the reduced weight of the foam allows you to have a more durable or heavy glass schedule with the whole board coming out the same weight as a lighter glassed PU/PE board.

    Never glass polyester over eps. THAT will turn it to liquid.

    It's really tough to see the "beaded" texture of eps foam through the fiberglass, but a good indication is to look right along the edge of the stringer, usually there will be little pockmarks that line the stringer because eps doesn't shape as evenly as polyurethane.
    Last edited by terra-firma intolerant; Jun 28, 2010 at 10:27 PM.

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    Quote Originally Posted by Recycled Surfer View Post
    You can't have a PU Board with epoxy resin - it will turn it into liquid.
    thats not true.. ive made several PU boards and glassed them with epoxy resin. Its a good combination too...easy to shape PU blanks, and epoxy resin is easy to work with and strong.

    i think you meant you cant glass an EPS blank with polyester resin...true... it will dissolve the foam.

  9. #9
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    i think its a PU with epoxy resin, it doesnt look like eps at all. And way to light and strong than poly resin

  10. #10
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    Quote Originally Posted by mexsurfer View Post
    i think its a PU with epoxy resin, it doesnt look like eps at all. And way to light and strong than poly resin
    Whatever the case if it rides good, that's what matters the most. Maybe take it to an experienced glasser to let them evaluate what materials were used. That way if it really is PU with epoxy resin, you have a future reference for board materials that felt good to you.