Im hoping to build my first board, a big light wind twin tip. The plan is to laminate together 2 sheets of 4mm plywood and then fibreglass the top and bottom. But so far things aren't going well.
Did my first test run yesterday and it was a failure. (I'm using west system epoxy resin with 206 slow hardener and 300gm fibreglass)
I just tested on a small section of timber, with some paddle pop sticks on it, to see how well the fibreglass would stick and form to shape. I also wanted to test my cheap vacuum system, which is just a hose attached to the deflate port on my kite pump.
well the entire thing was a failure
the kite pump pulled a good vacuum down to about -0.8 bar, but I couldn't get the bag to seal so it would hold vacuum for more then about 20 seconds.
then when I unwrapped it this morning I was not happy with the fibreglass. It didn't form well around the paddle pop sticks (this could be due to the vac failure), and it didn't stick to the timber very well. It looked good to start with but when I gave it a flex test the fibreglass started to unstick (you can see in the pictures where it has unstuck and turned white). I then just grabbed an edge and it peeled easily off the timber. I know some people only put their fibreglass to the edge and not around, so there must be a way to make it stick?
What am I doing wrong?
I messured the resin using a digital kitchen scale, so I know the mix ratio was right. I wet the timber first, lay the fibreglass on top and then finished wetting out the fibreglass until it was clear.
did I absorb too much resin out when I vac bagged it? I just used peel ply and a breather layer over the fibreglass.
do I need another layer of resin on top of what is there to so help seal it better? But doesn't that defeat the point of vac bagging?
Please help
Also, should I cut the fibreglass cloth to size before laying it on, or leave it hang over the edge and trim the excess once the resin has dried.