I’ve got a reshape going off an old board. Reuse and recycle, right? Anyways, there was some delam action going on with the original deck and I ended up taking the deck thickness down quite a bit. That makes me a little concerned about overshaping. I just got my hands on a vacuum rig and some bamboo veneer so I thought I’d use that for a full deck overlay. I want to do this partly to mitigate my concerns about the foam and partly to play with a vacuum process in a low-risk situation. I’m not concerned about weight with this shape, just strength and deck compression.
My question is this: has anyone here done veneers with polyester or vinylester resin? The reason I ask is because I was talking to a friend of mine last night and he expressed some skepticism about whether the VE I was thinking about using would even adhere to the bamboo. I have epoxy but I prefer VE when glassing a PU blank and I don’t necessarily want to use epoxy for the skins and VE for the rest of the board.
I was hoping you’d respond 'cause I’ve seen you post a couple PU/Veneer combos.
Good point about working time. I guess there’s also the superior flex factor of epoxy to consider. I reckon I’m already going to get a stiffer board because of the veneer + heavier PU foam. No point in compounding that.
Actually, that is helpful because my question is about adhesion. I reckon if the PE adheres to the exterior glass without separation under flex than that answers the one question (mixing epoxy under and PE over the bamboo) and gets me close to the other (using PE for the foam/veneer adhesion). Thanks.
I'm pretty sure Robim Mair has been doing some Pu blanks with Bamboo skins. I'm not sure if he's using epoxy or PE. But they look great. Check out some of the boards in the resource section or give him a call.
Personally I like epoxy. You need quite a bit of work time to do both sides at once. Remember you got to mix, lay out the cloth...for both sides. Line it up, tape it down....flip, lay it out, line it up. Tape it all down...shove it in a bag....get it air tight....oops something gets out of alignment, turn off pump..break seal...pull board out of bag...realign...put back in bag, reseal, turn on pump, etc,etc...
If this is you first go a vac bagging there's a 50-70% chance it might go perfect the first try...with epoxy. With PE, your sucess rate will drop to about 10-20%, and that's if your a fast worker. I'm guessing you could lower the cat ratios in the resin, but then your looking at the resin draining into the blank? I would assume that your work time with PU resin would have to be in the 10-15 min max range to make a light strong board. Just like a regular PU/Pe lamination. That time line with a vac bagging would make me sweat. Plus when it kicks.......your done messing with it. Epoxy gives you a nice wide window to mess with.
Yes, I have been doing quite a few PU blanks with bamboo veneers, but for all of them I have been using RR epoxy. I have been contemplating using PE just to try it out but am a little nervous about wasting a lot of time on it and not have it work out. Will be working on a board in the coming weeks that will be a hybrid, where the bottom and deck will get a layer of PE and then I will bag a bamboo veneer on the deck with epoxy and cover it with a layer of glass and epoxy, hot coat with epoxy, and then gloss with polyester. This would be over a PU blank.
Vinylester might be a lot better choice as it has much better properties than PE, I have used it extensively for boat building and have laminated a couple of boards with it. It definitely has much better adhesion properties than PE and is more flexible (well at least the stuff I used). Also have used it to glass over wood without any problems with adhesion. One of the boards I laminated with VE was CLEAR and that turned out to be a mistake as the VE left it with a sort of light brownish color, but the board was very strong. The resin I used (this was some time ago) was AME 4000 Epoxy Vinyl Ester (I think they have since dropped the 4000, made by Ashland), but the interesting thing is that they have always called it an EPOXY vinyl ester, which is what got my attention. But it is catalyzed like a PE resin and is pretty nice to work with as well.
We built a lot of big racing sailboats using this stuff in a vacuum bag and it had excellent performance characteristics, all of these boats had balsa cores so I think it is well proven in terms of the bonding characteristics to wood. We used this resin as an alternative to epoxy for high tech laminates to help control costs, although it was more expensive than PE resin.
I agree with Resinhead that the working time would be my biggest concern, but when we used the vinyl ester to build boats we were laying up some fairly massive panels that we vacuumed bagged (these were 70’ ULDB racing sailboats), so it is certainly doable with the right catalyst ratio.