I am looking into the possibility of giving the EPS/epoxy combination a go.
I dont really know to much about it so I thought I would experiment a bit one step at a time.
I will start with the epoxy.
I have a PU blank at home and I was thinking on doing an epoxy lam over the PU blank.
What are the pro’s and con’s of doing this combo??
I have also heard that epoxy is a lot stronger than polyester.
So would a lower density PU blank with say 2 x 4 oz dec lam and 1 x 4 oz bottom lam in epoxy be as strong or stronger than a medium density PU blank with 2 x 6 oz dec lam and 1 x 6 oz bottom lam poly???
It should be a lot lighter, but what about strength and performance?
an epoxy lam is generally stronger than a polyester lam. the epoxy, however, is more flexible. eps foam bounces back from the flex. polyurethane foam does not.
i’ve been using epoxy over PU for a few years now, and the results are good. but the lightest foam i’ve used is “blue”. anything lighter than that will be highly prone to pressure dents.
Most of my boards are epoxy over pu. Blue foam pressure dings easy, but I haven’t had any delams from epoxy bouncing back up. it just stays dented. BTW, I’ve been using 6 oz “S” cloth. Green foam resist pressure dings way more with the epoxy and S cloth combo, almost to the point that my green foam boards don’t pressure ding at all.
So, if epoxy is more flexable and bounces back and PU doesn’t bounce back, whouldn’t it be susceptable to delams?
over time, yes…just be conscious of it and fix what needs fixing. a board i made three years ago, glassed 6-oz bottom w/ 4-oz tail patch, double 6-oz deck over Clark Superblue foam, is as solid as ever – no delams, and no real dings to speak of. shaped it for a friend of mine, and it instantly became his go-to board, so it’s had plenty of use over the years.
If you have been using epoxy/PU for years, it must be a fairly good combination or you wouldn’t keep on building them.
i’m happy with epoxy resin, and don’t think i’ll be changing that any time soon. i’m starting to experiment more with different foams, but still primarily use polyurethane blanks.
Are they much lighter? can you afford to glass them lighter? how do they ride?
generally, i like a little weight to my boards. on the more performance-oriented boards that i may want a little lighter, i use an alternative foam to accomplish this. glass jobs vary between 6-8 oz bottoms (plus optional tail patch), 8-12 oz decks (plus optional deck patch), depending on the style of board, and what kind of foam i used.
Is there any more work involve with laminating or any more sanding etc…?
nah. in fact, on the whole, i think the process from start to finish is easier.
while on the subject. I’ll be doing a PU/ epoxy board soon as well. If i’m understanding correctly I don’t have to seal the blank prior to lam? Unlike an eps blank.
I have several PU/Epoxy boards. The only one that went south was a super light Clark foam chip that shruck up from too much heat while it was in a board bag. All the others are fine.
The most important part of the laminating process is this: Get your blank nice and warm and the resin to about 75 degrees. Then put the board in a cooler setting and get the resin out of the pot as fast as you can. This will give you lots of time to work and prevent any off gas problems. You don’t want the blank to blow. You want it to suck. I have come to prefer basting the whole blank with opaque colored resin/Qcell runny paste. I put it on with a roller. It works very nicely and makes for a very nice shell. Epoxy is light so boards come out at weight that suit me quite well. 8’8"x14.75"x21.0"x15.0"x2.875" out of Aussie Green finished at 12lbs exactly wrapped with double 4oz and two thirds 4oz. deck patch.
Additive F is a sanding agent produced by Resin Research for use with their epoxy. i believe Fiberglass Hawaii also has a sanding agent for their epoxy. don’t know about any other manufacturers…what brand of resin are you using??