Resin Infused Surfboard

Having made a 7'6" Minimal, by hand lay-up and vacuum bagging, I wanted a system that reduced the time spent sanding laps and pleats. Also I disliked the race with curing resin!

My new board is 9'2", for those lazy little summer waves. Having snapped a board last year I decided to go for strength and use a glass / kevlar cloth and a superb epoxy (RS-L285) with a slow hardener from PRF in Dorset. The resin has a 5 hour working time, a little long for many operations but for a first project and the summer heat I was taking no chances.

I carried out a couple of small scale tests to try and establish flow rates through the laminate stack I'd chosen. The samples produced were subjected to a tensile test to get an idea of the strength difference between plain glass and the kevlar glass mix I fancied.

Using resin infusion, all glass (top and bottom) is lightly attached to the blank, pleats cut and overlaps made with a very light dusting of aerosol re-positionable contact adhesive ( frame mount) to hold it all in place. Using the same spray, a layer of peelply is applied to the whole surface, this allows resin to bleed through the laminate stack but is easily removed once the resin is cured leaving a textured surface ready for the glosscoat. A resin distribution mesh is then applied. It is made of an open weave nylon fabric and allows the resin to pass fairly rapidly over the laminate until it meets the peelply where it slows down and completes the penetration of the laminate stack. Finally the suction lines and resin feedlines are positioned, a vacuum bag is sealed around the whole lot, the feedlines clamped off and the vacuum pump started. Now leaks must be traced and sealed, this is essential.

As the vacuum begins to pull down, one has time to reposition anything that may have slipped or moved. Indeed as the resin is not even mixed at this stage there is no rush and one can open up the bag to modify the set-up until one is completely happy. The pump was allowed to run for half an hour to ensure the whole lot had degassed and leaks were checked by clamping off the suction line and watching the pressure gauge. Ideally it does not drop at all but a slow drop is almost inevitable. I was delighted with the set-up as there was no pressure drop at all over 5 minutes which shows good vacuum integrity.

Now the most nerve racking part! Estimate resin quantities, mix it, open the valve and watch it flow.

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