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Composite Laminating

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I wonder if this will be a topic of interest to some folks. I've recently taken it upon myself to make a hydrofoil kite board, laminating with mainly fiber glass and vacuum bagging the parts . I have to say that I have a new found respect for those who do it and do it well. The project has cost hundreds in materials and and equipment, (vacuum pump, consumables etc) and many hours on YouTube. But still I find it a challenge to get great results. As well as making the hydrofoil I've modified an old Liquid Force surf board by shortening it and dropping in the fin boxes to attach the base plate of the hydrofoil.

It has been a long, hard slog but i think I might get the whole thing finished in a couple of weeks!!

Any way, I suppose I interested in others experiences with laminating and Vacuum bagging. There is plenty of info on the internet but mostly they talk about 'How To' and very rarely What To Do when the results are not great or need to be improved.

The Mast was the first part I vacuumed as it was the simplest shape to do and it came out alright. But the other shapes were a different matter with varying degrees of finish. All parts were 3D routed out of 50mm Paulownia wood.








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I’ve vac bagged 2 boards now, with average results.

slow set epoxy gives more time (and less stress) when setting up

light weight fibreglass helps get into the corners.


what did you use for a vac pump? I just cut the compressor out of an old fridge I got off free on gumtree.


Check out kiteforum.com there is a gear builders forum with heaps of info


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I bought a proper vacuum pump off eBay. It's probably overkill as it's pretty heavy duty, but i was thinking ahead that maybe I'd get more into composite stuff and even bang out some boards etc, before I realized how involved it was.

Using light cloth sounds like a good idea. I get lots of problem with the E glass 600 not compressing into internal filleted corners.

I suppose it's like any new endevour; you get better with practice. I'm at the stage now of sanding back the places that are rough and putting new layers over. I'm slowly inching my way forward. My carbon cloth arrived in the post yesterday, as i was thinking to put a final layer on the mast, base plate and fuselage mostly for aesthetics.

But the wing and stab'  look really nice with the wood grain showing through the glass so am going the leave them like that.

I'll put up some more images once I get things close to finished.

Thanks for the link Andy, I'll check it out.


vacuum pump.jpg

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Yeah 600 gsm is pretty heavy. I think from memory I’m using 250 or 300. You can always add extra layers.

you will need to clean off the blush, waxy build up, from the cured resin in between layers. It’s water soluble so warm soapy water and green scourer works well.

or if you use peel ply when vac bagging the blush comes off with the peel ply.  

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Putting on extra layers, I came to the same conclusion, but still with the 600 gsm. I'm sanding the foil parts back and leveling any wrinkles then bagging another layer of glass. It's slow work, having to wait for the epoxy to harden, but I'm getting there. I experimented with a filler coat of some micro balloons tonight, mainly on the leading edge of the front wing and a thin coat all over too to see if it will fill in a couple of place where I'd saned through to a void. 

I used 400 S glass on the board of which I had some terrible results once I came do doing a sanding and 'hot' coat, really bad pooling. Now I'm wondering if it has something to do with the waxy coat you speak of. But I did sand all shinnies off so would have thought that would be enough. Anyway it seems to get less of a problem towards the end, but I still don't know why I had the problem in the first place, I did all the correct steps- sand with gloves on, don't touch with hands, clean brush etc. I also wondered if the yellow pigment effected things as I tried a coat of epoxy on the nose piece of the board I chopped of and it went on no problem.

One thing I would never use again was the Inegra. If you sand through to it it just fluffs up, bloody nightmare trying to cover over it. I thought I'd try it as extra reinforcement over the fin box as at the time I was low on cash for CF.

Have you put any of your builds on here?

Below is a couple of attempts of hot/sanding coat

and the front wing with the micro balloons filler coat. It's coming together...then I got o learn how to foil!




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Yes, router number two as of the 2015. I did have a little Chinese 6040 which i did my wheel on. This one is 1200 x 1200 MultiCam machine. Actually during the the routing of the last part, the fuselage, the Z axis stopped working properly. So after this foil is finished I'm doing a major upgrade of the mechanics- new Z axis and raise the gantry height by about 150mm... big project. But will be a much better machine.


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