So I’ve been continuing my innegra tests, always with CJ’s words in the back of my mind- “To make a light board, use little resin.”
So on my little test patches I’ve been pulling the lam as dry as possible. Really scraping every last bit of resin off. My thinking is that any pinholes or any other passages where water could possibly get through to the foam will be filled by the hotcoat (the aussies don’t call it “fill coat” for nothing, right?).
Am I wrong?
Does any one here pull their lams as dry as possible?
I think if there are problems with that it is from the fact that resin sets in a fairly short time and is a fairly thick/viscous liquid so you when you “fill coat” it does not have time to make its way down into some of the uneven and oddly shaped pinholes and tiny gaps and maybe won’t completely seal them all off. Water on the other hand, is much “thinner” and the board will be soaking in it for hours at a time, allowing seepage. Also, limited experience here, but I never could get a “dry” lam to look right in finishing, you could always see that it had been done too dry.
I pull my lams to just before you start seeing white on the top. Shows if you use color. But with a scraping motion, without pressing down, it doesn’t remove the epoxy from below. Vaccum bag is really what you want, because it squishes the lower epoxy to the surface, creating a hot coat.
Here could be the hot tip. Not sure yet, because I’m still experimenting, but look up Cerex N-Fusion Surfacing Veils. I just ordered 250 yards of titanium oxide white in 1.3 oz. It is a nylon 6,6 that is supposed to smooth over the weave, make a permanent white surface, and be better for abrasion than fiberglass. Abrasion resistance means you won’t sand through it. Also Nylon can be dyed. Think artistic there!
Bud of mine made maybe 130 boards around 8'4" x 20.5" wide, usually 4" thick. Almost every single one weighed in under 12 lbs., with mast track, footstrap inserts, thru the deck fin box. Triple 4oz decks with feet patches, double 4 bottoms, 1lbs styro, NO VACUUM bagging, just hand layups with a rubber squegie. At least 125 of them lasted over 5 years, no leaks.
Secret is careful judicious squeegie work, maybe 7 lbs downward pressure, then a pinhole fill coat SQUEEGIED in at 30 degree angles, mix of 40% epoxy and 60% micro ballons, HAND finished (with rubber gloves).
Another more famous bud, MikeZ of ElSobrante, is considered the premier windsurf and kiteboard custom maker. His boards are stronger than ANYONE's, in the whole world. Until 2000, he exclusively hand laid every board, no vacuum. He started bagging around '98, but was never convinced until 2001. His $2,200 Formula boards are 6 months in demand, his $2,100 slalom boards have a waiting list of at least 10 guys.
Average 8' x 26" slalom windsurf board is right at 12 lbs for the strong ones.
To chime in now may only help clarify
other solid input here.
Dry lams for INNEGRA are only possible for
vacuum bagged parts or 2 step process because the HDPP thermoplastic yarn
INNEGRA has a specific gravity of 0.8: it floats!
Wet lay up techniques will only
encapsulate the fiber(never saturate) and if so all that is needed is intimate
contact to foam. Come back in second stage with "fill coat’. It is also
necessary to follow up with a fiberglass cap sheet 2.3 osy or 3.6osy for
any chance of surface finishing. You don’t want to sand the stuff.
Use epoxy only for adhesion and matched
toughness to supertough HMPP. Great properties INNEGRA, too bad not enough
poeple are using it to justify hybribizing a fabric with fine filament
fiberglass.
A 3.5 osy balanced weave at 50inches is
the best we’ve been able to commercialize, so really only for kite boards,
sail, wake and SUP, as it is hard to get light enough weight for
performance shortboards.
“Twenty
years from now you will be more disappointed by the things you didn’t do than
by the ones you did. So throw off your bowlines. Sail away from safe harbor.
Catch the trade winds in your sails. Explore, Dream, Discover.” Mark Twain