First EPS board

General Discussion
1

H everyone! I’m currently shaping my 5th board. First two boards were PU foam, poly resin. Then I fall in love with RR epoxy and use that on the remaining two PU foams. 

They’re all too damn heavy. My most recent one, which is like 6’5’', is 11 pounds!

So I switched to greenlight’s mail-to-you EPS foam cores, and, like, wow are they light. I think I have solved my weight problem.

The thing is, as everyone says, EPS can be hard to shape. I’ve followed all the suggestions – leaving extra space, going straight to light sanding. (The planer took major divots that required taking the EPS way down.) 

I’m close (although I took a little too much material), but i’m left with one final hurdle before glassing – i have these tiny little divots everywhere. Millions of 'em. Look:

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Thing is, i don’t want to take anymore material – the board’s too slight as it is. Can i just leave those and glass over them and assume the epoxy will fill in the holes? 

I don’t have to make it as smooth as a PU board before glassing, do I?

Thanks for any and all wisdom!

 

2

Lightweight Spackling Compound is useful for filling such holes. Just make sure that is is the white kind and not the kind with paint/primer. Thin it a bit with distilled water, apply, let it dry, and sand off the hight spots.

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3

Seal it up as suggested above, I prefer a resin/microballoon mix.

Once sealed, you will find you need less resin for the lamination layers…helps you keep the weight down a bit more.

4

gents, i have something called cab-o-sil – would that work for this purpose, mixed with some epoxy resin? 

5

I think you will want spheres instead of fumed silica:

https://www.expresscomposites.com/cabosil-fumed-silica-thickener

Cabosil(Aerosil, Fumed Silica) is a thixotropic paste designed to give resin vertical hanging capabilities.  It works very well with epoxy and polyester/vinylesters.  It has a clear appearance when mixed.

https://www.expresscomposites.com/hollow-glass-spheres-lightweight-filler

Microballoons added to epoxy or polyester/vinylester will make an easy to sand filler. The microballons space out the chemistry so that you can use a thick cross-section without it overheating and distorting.

6

I prefer resin+microballoons, too.  But most professionals seem to like the spackle better.  

 

You glassing may be turning out heavy if you’re flooding the lamination and fill coats.  Epoxy has much better adhesion than PE resin so you can run those lams a little drier.    When I laminate I waste very little of it on the floor.   You just can’t lainate it so dry you get pinholes or air bubbles.  

7

okay, and just want to verify – you’re talking about microballoons like this:

https://www.amazon.com/Phenolic-Micro-Balloons-Epoxy-Filler-ounce/dp/B073NSCWC1/ref=sr_1_3?ie=UTF8&qid=1533939714&sr=8-3&keywords=microballoons+filler

also — i can use this mixed w/ “Resin Research” epoxy on EPS foam, right? 

i’m planning on using the slow hardener because i’ve heard about problems with heat. 

8

Nope, those are phenolic/brown ones, just like it says in the full Amazon description.

They would probably look nice on an epoxy fillet for a wooden boat but not on a white EPS board.

I would go glass spheres and whichever surfboard-grade resin you are using on the rest of the board.

I am still spacka-licious so I cannot say much more other than I only use glass spheres on ‘special’ projects and fumed silica on ‘super special’ projects.

 

A ? for those who do use epoxy slurry: how much resin and spheres do you use on an average board?

 

 

 

9

I’ve found the lightweight spackle from Sherman Williams to be the easiest to work with. Fill voids as clean as possible then a light sanding after.

 

10

okay all thanks for the suggestions on spackling, i will go with that!

i see in the video jrandy shared – nice technique! – he is using this:

https://www.homedepot.com/p/DAP-Patch-N-Paint-32-oz-Premium-Grade-Lightweight-Spackling-01611/100094504

i’ll get some of that and give it a shot, thanks!

11

Be careful with the Home Depot spackle. They made changes and I don’t know if that product is the same as it was a few years ago. Search Spackle here and you’ll see that most people are using the Sherman Williams spackle now.

12

got it, thanks!

13

just closing out the thread – sherwin spackle application a success, i’m all set. much appreciated!!