How do you know for sure that Innegra, Kevlar or Carbon is wetted out?
It’s pretty easy to see if fiberglass is wetting out. If it comes out clear, then there’s no air. --why? I think that the speed of light in glass, epoxy and polyester resin are the same. The speed of light is different in air. So if there is no air between the fiber and the resin, light waves don’t refract. If there’s air, you get refraction and it’s not clear.
I’m going to look at Innegra, Kevlar and Carbon with a microscope to see if my layup methods are effectively wetting out? Is there an easier way to do this?
For some fabrics it may be necessary to resort to destructive investigation. Breaking or slicing through the laminate might allow microscopic viewing of the cross sections where lack of saturation of the individual strands or bundles would be more obvious. Kevlar for instance almost seems resin-phobic and the fibers are more 'encased' than saturated. Carbon fiber too but to a lesser degree?
With a sensitive scale it might be interesting to weigh standard sized sections to determine exact resin to fiber ratios?
PS - Per your results on laminate research, on my most recent personal board I am glassing with double 4 oz with the cloth layers pulled lengthwise at opposite corners to approximate multiple angle weave. It's not true bias weave cloth but I'll settle for my poor man's version for now.
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John raises an interesting point. My experience with Kevlar, and it's limited, is that if the cloth isn't thoroughly saturated, you won't be able to cut it with a razor blade as your resin kicks. No way, no how! When the epoxy gets to the stage where you can trim a cutlap, the kevlar will behave like regular fiberglass cloth in that you can trim it with a blade. Before or after it gets to that stage, it's not gonna happen with the blade. Too early and it skips over the cloth, too late and you need a saw or a grinding disk. BTW, it's been my experience with kevlar that it changes color a bit as it takes resin which helped me with the laminations. Innegra goes a bit more clear as it takes resin, but wasn't all that difficult to squeegee excess out in a hand lam. CF is a bit more difficult to quantify, but it seems to saturate readily enough. I think the issue there is that you may leave too much resin in the cloth if you're not vacuum bagging it. Definitely a lot to be said for "feel" when it comes to hand laminations using these materials.
Here's a board with a double 2 oz. kevlar inlay with 4 oz e over and under it.
Good explanation of the light through resin and glass. I guess this is why just about anyone can glass a clear board to look cosmetically acceptable. Where the fibres are, or not, is easily disguised. Oversaturation is easily disguised also.
The more exotic materials is where experience definitely plays a much bigger factor. You can use procedural techniques to ensure adhesion and saturation, but these are also learned by experience.
This is all relative to whether you are using open hand lamination or closed under vacuum.
For some fabrics it may be necessary to resort to destructive investigation. Breaking or slicing through the laminate might allow microscopic viewing of the cross sections where lack of saturation of the individual strands or bundles would be more obvious. Kevlar for instance almost seems resin-phobic and the fibers are more 'encased' than saturated. Carbon fiber too but to a lesser degree?
With a sensitive scale it might be interesting to weigh standard sized sections to determine exact resin to fiber ratios?
PS - Per your results on laminate research, on my most recent personal board I am glassing with double 4 oz with the cloth layers pulled lengthwise at opposite corners to approximate multiple angle weave. It's not true bias weave cloth but I'll settle for my poor man's version for now.
Has anyone done it like they do in the videos showing guys applying resin to sheets of cloth on a piece of plastic cloth then applying that cloth with the wet side down to whatever they are working on, then applying more to the top side. Of course most of this stuff is then put in a vac bag and oven.
Just curious. I have some carbon, but have not tried using it. I’m figuring I will vacuum bag it when I do.
OK..I'm just a dumb surfer....30 years ago I worked in a factory making a product known as "prepreg". Why on earth are you doing hand layups with Carbon fiber and Kevlar and then doing all sorts of testing when you can buy "prepreg". Yes, you will need some extra equipment but race cars and trick boats are built in a high tech fashion not with hand lay ups. Surfboards are not high tech. The Space Shuttle just got sent to the old folks home. Lots of carbon fiber there....
Maybe the heat and vacuum when using prepreg will ruin your shapes....It's just a pool toy.
Come on now, just drink a lot of water and your fiber will be plenty wetted out. If you cant poo then it is not wetting out ( or maybe you aren't getting enough fiber ) !!!!
Weigh the cloth , mix up about 10% to 20% more epoxy than the cloth (by weight) then vacuum bag…
With carbon and kevlar you gotta push hard and make sure it all wets out but you gotta watch out for frothing the resin …Scrape off any surface resin that’s white from overworking and apply fresh epoxy if needed…
Finally: Don’t scrape off all the epoxy like you would when doing a hand layup but let the peel ply and breather do the work… If you need to wet it out further do so… You want a slightly resin rich laminate when it goes in the bag… Make sure you seal the blank when bagging and you’ll never get dry spots.
Or spend the extra money and buy pre-preg cloth…
If you’re spending $30+ a yard for high tech. cloth, I see no advantage in applying it using a low tech method such as hand lam… jmho… Unless you want a cosmetically perfect weave pattern showing off the carbon or kevlar… The tension of vac.bagging can distort the weave pattern sometimes, especially around the rail laps…