What McDing said. Sand, don’t cut, carefully sand flush what sticks up, carefully fill what has gone down and sand that flush, then use cloth over in several wider and wider layers so you don’t get an abrupt transition in the glass strength. And you’re done, the board is nice and strong and if you do a good job, the repair looks good.Don’t worry about more than one layer, it doesn’t weigh much and if you go a few inches bigger on every layer, it’s nice and smooth.
For some reason everybody wants to cut out glass, get down to foam. Or worse still, cut out foam. A few things about that. My little rant -
First, you are not taking out just glass. You wind up removing the foam that is stuck to the underside of the glass, usually a good deal thicker than the original lamination, plus there’s always chunks. Just laying in cloth in your cut out to the original lamination schedule won’t be enough to bring it back flush. And those several laminations will make a very hard patch that isn’t tied in to the rest of the board, so it will most definitely flex differently, And break loose.
So you get cute, lap your filler patches onto the original glass to tie it in a little. Yeah, okay, so you have glass building up at the edges of your cutout ( that you wind up sanding down to nothing and negating any good effects) and you still have a low area over your cutout that you have to fill somehow. See where this is going? Essentially the same thing as the first case, just more sanding.
So you go a little wild with resin/aerosil mix, fill your divot with that instead of cloth. Yeah, that’s neat, except you have to sand it flush, and lay cloth over it, and you still have that transition from original glass to filler, and the skim coat of filler is relatively brittle. When it cracks under stress, and it will, it will likely compromise the glass you put over it and that will serve as a lovely starting point for the next buckle.
See where ll this goes? . None of it good. And extra work into the bargain. So put the knife away, get out the sandpaper and have at it.
hope that’s of use
doc…