Hey guys, I am building a simple Pump Foil Board and wondered whether these air bubbles significantly reduce the overall strength of the board. I will be adding 4 layers of 206g/m^2 per side and the core is 1,8cm Paulownia Wood plank.
It’s already my second try to laminate without getting the air bubbles but even with lots of care I cant manage to get rid of them.
Do the bubbles seen in the picture drastically reduce the strength of the board or will it be fine as it is?
Hopefully someone can help me out.
Have you tried a thin resin pre-seal, then sand with 150 before laminating? Experiment with a piece of scrap Paulownia.
I had a layer of fiberglass on top before but then sanded it completely down. So it should have been sealed. The bubbles didn’t come up from the wood. I just didn’t manage to get rid of them during laminating.
It might not seem like it, but they probably are from the wood yet. From doing wood canoes and a few surfboards, here’s what I do.
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Always glass in the evening as the temperatures are falling. If you do morning or midday, rising temps expand the air inside the fibers and hollow board and then bubbles push up and get trapped under glass.
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As Stoneburner said, a cheater coat to seal the wood. A small amount of resin, pour and spread it, then try to squeegee it all off. Use a squegee, not a brush. You should almost have as much back in the cup as what you started with. When it is dry just lightly scuff it with a Scotchbrite pad before you glass.
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Get absolutely all the dust off. It’s hard to see in the pics if it’s the case, but if you have small grains under the glass, they lift the fibers and the resin bleeds away leaving a bubble. sometimes you can work them through the weave, but it’s best to not have any. Very last step before you glass, hold a 60cm piece of masking tape taut between two hands and run the sticky side over the “Clean” board. Amazing what that picks up from even when you think there was nothing left on it.
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Hey, thanks for all the tips. I’ll try to implement them next time.
But do u think it’s fine now how it is or do I need to do something about it?
I am worried about the structural strength.
I would ride it as is. Yes, there is a small loss in structural integrity, but unless you are putting radical stresses on the board, I don’t think you’ll destroy it. Wood is porous, fibrous, and tough, and you do still have a significant bond fro the bulk of the cloth to it around the dry weave.
These are probably going to bug you more from a cosmetic standpoint than anything.