Bubbles after lamination - newb


It is my first post on this forum. I’ve been reading it for a while and now when I decided to build a board i would much appreciate some help.

I am building a SUP board (I know its lame :] but i live in Poland and our Baltic Sea don’t have big waves and i am living far from it)

I use EPS for core, ply stringer and epoxy. My problem occurs few hours (3-5h) after lamination. The glass was nicely, evenly spreaded. I think i have wet it completely with epoxy. And then i get these bubbles. They were not there when i finished the lamination process.

I am a newb and i know it but i try to watch all the vide on on fiberglass hawaii and other good resources.

I have made some tests on not shaped EPS and i didn’t get these bubbles.

After shaping my board is not perfect, i have some small holes from little “spheres” falling off during shaping.

I am soory for this begginer question and for my english.

Berst regards

You were very close to perfect.

When you squeegied off the extra epoxy, you pulled the cloth a little too tight. So what happens is, it slowly creeps back to where it wanted to be before you stretched it.

Next time, make sure not to drag the cloth with the squeegee.

The fix is to take your sander, and sand through the bumps, so you expose the foam again, just at the bump.  The apply a small patch of cloth over the exposed foam.

I’m still on the learning curve for glassing… but the guy at the board supply shop told me where I went south. He told me to squeegee out as much RESIN as possible without causing air bubbles. It’s working.

Just a guess, but it could be the temperature in your lamination room.

 EPS is quite temperature sensitive and if the temperature rises before the epoxy has cured the air between the spheres in the EPS will expand and cause the lamination to lift off the foam

Try to laminate EPS in an environment with a falling temperature (evenings work well for me), sealing the eps with spakle or epoxy/filler mix can also help, both cosmetically and to prevent this problem.

I always make sure boards are kept in my lamination area and the temperature has been stable for at least  4 hours before I laminate.

Hope that is of some use to you

Good luck


Both Everysurfer, and Offshore, have given you excellent advice.    How to fix, and how to avoid.    Follow, and your troubles are over.

You have a few small blobs on a SUP…Hot coat it and move on…yes, we are “overthinking”.

…well, you and everysurfer are overthinking…stop staring at the lamination…go stare at a bikini.

Unless those little bumps can be easily compressed with a fingertip, move on.  If you can compress them and it seems like there are air pockets inside, try a simple injection of epoxy using one of those epoxy syringes with the molded tip.  Slap a plastic bag with a weight on it and when cured, fill coat the board.  You’ll be fine.

I can’r remember who taught me this, it might have been petey, but I will baby sit the board with a razor blade and when these things pop up I poke them with the corner of the razor, and push them back down. This happens more with XPS and warm ambient temps.

Thank you for this amazing advice.

Yesterday i have sealed the eps blank with epoxy and right now i finished the lamination.

Small discovery. When i turned on a flashlight and directed the beam almost parallel to the fiberglass I saw air bubbles trapped between the layers. Squeezed them with a squeegee. 

I have used 3 layers of fiberglass (200 gram / square meter) on deck. Isn’t it too much?


 Yes! There are no bubbles.

Thank You.

I am just wondering, if I use epoxy to seal the eps and then go with fiberglass followed with hotcoat and glosscoat, do I need 3 layers of 6oz cloth on deck? I will put EVA on deck at the end. What is the purpose of extra cloth on deck? Isn’t the biggest stress on the bottom due to the weight of a person?  


Hi -

It depends on the density of your foam.  Unless it was super light foam, 2 layers and the EVA pad would likely suffice.  I have thumb tested some lightweight paddleboards and have been surprised at how easy it is to ‘oil can’ the fiberglass skin.