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Joining plascore

Joining plascore
January 09, 2017 06:16PM
OK, making sure I've understood everything I've read correctly.

1) lay visqueen on plywood table
2) wet edges of box joint and then fill with thickened epoxy, push ends together
3) wet plascore, lay fiberglass tape across joint and wet out
4) more visqueen across the joint, flat board across joint, and some heavy stuff on it to keep it flat

Do I need to fill all the open honey comb with thickened epoxy? Anything I've missed?
Re: Joining plascore
January 10, 2017 12:26AM
Glad I made a test joint! That was pretty sloppy. I took my cut out pieces and then made mini box joints on a couple of my scrap pieces.

My issue was when I pushed the pieces together the sides of the joints scraped away the thickened epoxy away, but the butted together ends worked out OK.

Why am I trying to minimize squeeze out? Structural purposes or for the sake of easier sanding and clean up before glassing?
Re: Joining plascore
January 10, 2017 01:43PM
If you join the Plascore one day and glass over the next you need to minimize squeezeout so you don't have a hard lumpy mess to glass over later on. You hardly need any putty in the joint. A small amount of putty between the cut sections of plascore forms a bit of a mechanical lock in the joint. It's probably not necessary at all. I've always added a small amount of putty to the joint but I'm not convinced it's needed.

You can put a full layer of glass over the joint on the top, exposed side but you can't flop the panel over and glass both sides. So minimizing squeezeout is important no matter what..........so you don't have that lumpy surface to deal with.
Re: Joining plascore
January 10, 2017 11:05PM
Damn, this stuff is strong! I couldn't snap my test panel at first. Tried with my hands and pushed it against the edge of a step, and could not snap it.

Then I broke out a small crowbar. Saw some scratching maybe a few cracks when I had it laid on the concrete floor, but no serious damage.

Clamped it so there was nothing supporting the unglassed back of the joint. It finally broke, but not across the length of the joint, and not all the way through.

Flipped it over and hit the unglassed side and did not get the glassed side to crack
Re: Joining plascore
January 10, 2017 11:26PM
A couple shots showing the above experiment, and a shot of the basement. Using the recommendation from above, and layed glass with no thickened epoxy in the joint, weighed it down alittle so it stays flat. Will grab a few syringes from work tomorrow and fill any gaps. Thank you everyone for your help.

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