Had a customer today send me a messgae that he had creased his board. Board is only 5 surfs old, PU stringerless with Uni carbon on bottom, 2 4 oz + patch on top and 1 4 oz on bottom, glassed with RR epoxy.
Now I have made around 50 boards so far, most of them PU foam, epoxy glass, porbably about 50-50 stringered and stringerless and only had 1 snap and now this one crease. The first one was stringered and glassed 6 + 4 top, 4 bottom, and it was destroyed by a wave that would have destroyed most lightly glassed boards, so I wasn;t too fussed. But the one creased today has me perplexed.
After thinking into it - I remember bath of these boards had acrylic paint on the foam and then glassed over, where most of my boards i glass clear and paint on top, or do resin tints. Could it be that the epoxy is not bonding as well to the acrylic, as what it would to plain foam, causing weaknesses? Or is this just a coincidence??
Pirate, sometimes if paint is put on too thick, it can prevent the resin from penetrating into the foam. That usually happens if applied by hand or brush. If it was airbrushed, probably not the problem. It is kinda like some Extruded foams, mostly a surface bond.
If I had to guess, I would suspect the lack of a stringer. Even with the use of some form of Carbon Fibre cloth, stringerless boards tend to flex a little beyond where a stringered board would. They do buckle and break.
Try wider laps. It adds a lot of strength.
Maybe try evening up the strength by putting double 4oz. bottom or a single 6oz. bottom. Makes the boards strength even on both sides.
One other question is, are you sealing up the foam before the epoxy lam? Some do, some don’t. Personally I don’t. I like to let that strong resin soak and penetrate the foam. It makes for a really strong board.
you may have accidentally used alcohol based acrylic rather than water-based? It’s my understanding that you should only ever use water-based paint directly on the foam, as the alcohol based paints can eat away at the foam or cause weakness
This makes the most sense to me. When I think of a poor bond between the glass and the blank, I think of de-lam, not creasing. A crease indicates the board flexed beyond the capability of the foam and glass to spring back to normal. If that was caused by a weak bond between the glass and the blank, the glass would have separated.
Photos always make situations like this a bit easier to grasp.
Plus, the op mentioned the board is only 5 surfs old. But if the force of a breaking wave hits just right, it will damage a surfboard, irregardless of how many surfs old it is. It sounds to me like the buyer is complaining that the board was inferior, when in reality, any time you take a board out into the impact zone, you risk damaging it.
The paint was definately water based and too thin.
I’m thinking this one was just bad luck and its a coincidence that the two that have buckled were both painted.
i normally keep the laps pretty wide on stringerless for the strengthening, and sometimes even run a tap of 4 oz around the rail. maybe i went too narrow on the laps on this one - i’ll double check when the guy brings it back for me to see if i can fix it,
I think Barry put down very well, and I agree. Boards break all the time, and the way yours was glassed it was only a matter of time. I suggest including some of the things he mentioned to increase the strength in your next project.