yes, you can get away with sanding resin for the glassing, you just need to either do your hotcoat/gloss before it sets up much or else sand it lightly or wash it with styrene or acetone to get rid of the wax film on top of the sanding resin. I prefer to do the wash method; you don’t weaken the cloth any and it gets into the little crevices and such in the weave that you get if you squeegee the cloth a little for the best lamination.
meanwhile, back at Toes Over’s board…
DO NOT CUT ANYTHING!!!
I MEAN IT!!
Nice, simple repairs get to be major projects when somebody goes cut-happy or router-happy. Leave well enough alone. Put the knife away.
Likewise filling with foam. Look, everybody talks about putting in chunks of foam, a few do it, and I have maybe seen two who did it right…over 30+ years in this business. And lots who did it badly - very badly. What’s REALLY amusing is when somebody tries to bed the foam chunks in a molded cofferdam type deal and pour in resin or sloppy-wet cabosil mix around 'em.
foam floats in resin, you know…
they wind up with this sad, foolish pool of resin with foam chunks floating on top of it, like the marshmallows on top of a Jello fruit salad and about as useful.
Okay? Good. Don’t go nuts on this. This isn’t a major puncture, right, it’s a dent in the bottom with concentric rings of cracking in the hotcoat and gloss, like a bullseye. You don’t need to cut anything, just fill. And sand a little with maybe 80-grit, by hand, with a fingertip maybe, to roughen up the surface so the resin will adhere. Don’t go nuts sanding, just rough it up a bit.
Then, clean it well. I would use clear resin to fill, no cabosil. Why not?
Well, what’s the function of cabosil? It does two things - first is it makes a paste from a liquid so you can wad it in and it won’t sag on a non-horizontal surface. But the problem is that the thicker it is, the more it tends to get bubbles trapped in there, which are a bad thing. Either they crack or you wind up sanding into them and have to do the whole filler thing again. And cabosil mix never levels itself, there are always mounds or lumps that you have to sand. Hassle city. Don’t use it unless you have to.This is a flat surface ding that doesn’t go all the way through, you don’t have to.
The other function of cabosil mix is as a filler to mimic foam, so you don’t get a translucent or near-transparent chunk showing like you would if the ding went well into the foam and you filled with clear resin. Cabosil mix goes off white-ish, and looks like a blotch if you use it on top of cloth.
You don’t need or want to have a blotch, you want something clear. Plain clear resin, maybe even thinned a little with styrene or acetone so it’ll level better and seep into the cracks you’ve described. And pour it a little less than ‘full’, so your cloth has someplace to go.
Get out your 80 grit again, sand lightly to give it some ‘tooth’ so the cloth will stick to the resin fill and to deal with the sanding resin wax .
Then, it’s glassing time. yes, use cloth, or else the filler can crack and fall out and where’s the fun in that? You want some 4 or 6 oz glass cloth, sanding resin and a throwaway chip brush or squeegee. For somebody who doesn’t do a whole lot of glassing, the brush is the way to go. Set the cloth over the filler resin and brush in just enough resin to make the cloth transparent with no bubbles. Your patch shouldn’t extend beyond the edges of the original depression.
Let that harden, sand the edges to feather it smooth with your 80 grit pal. Just the edges, not the whole thing, and lightly. For the rest of that, you do what i described above with the acetone or styrene to get the wax off the very surface of the cloth, so your hotcoat will stick nicely. If you used laminating resin to do the laminating, cool, you can skip that part, otherwise, it’s acetone time.
No sanding block, by the way. Again, I have seen guys get into a lot of trouble with sanding blocks, including one swifto who managed to sand through the original cloth on the rail of a board. You can get it plenty close enough with your fingers and you are a whole lot less likely to screw up something in a moment’s inattention.
yes, I might attack it with an 8" disc sander. That’s me and a lot of time in with one. And a lot of screwups back when. The Hippocratic Oath comes in here: ‘First, do no harm’. Go with the method least likely to make major problems if something goes awry.
Okay, hotcoat time. Mask around the sanded area. Brush on resin with a new throwaway brush, enough to do a little more than fill the weave of the cloth and blend the edges. Pull the tape, as Kokua said, and if you’re lucky you’ll be pretty near good to go.
Otherwise - if it’s not as smooth as you’d like, then as I described before, wet sand lightly with finer and finer paper, up to 400 or so if you are gonna polish it or 600 if you’re not. And then you’re good to go.
Oh, and Chano - I happened to be looking at the latest issue of Fine Woodworking ( check the local library ) and they had some kinda neat racks in one of the articles, described as ‘lumber racks’. Easy to build with simple tools and they’d work real well as board racks.
hope that’s of use