Can I glass over a Gorilla glue join using PE resin, or do I need to use epoxy so it doesn’t “melt” ?
If I am right, gorilla glue is PU resin so you can use PE on it.
Lemat speaks true.
As has been said, it’s an expanding, foaming water catalysed polyurethane adhesive, chemically quite similar to polyurethane foam s you will find in blanks. Works fine with polyester or epoxy resins. Needs a little moisture to go off properly.
Some things about it -
Comes in ‘original’ and ‘white’. The original cures to a pale brown that is a fair color match to ‘suntanned’ foam on older boards. The white is ( surprise surprise) white, a good match for newer foam.
While it’s chemically real similar to polyurethane foam, there are no reasons not to use it for a good filler or adhesive with polystyrene foam. .Works fine.
You want to confine it as it goes off. Like when they make foam blanks, the better it is confined the denser and stronger it will be. Clamping or using a gluing jig ( as you did, nice job) , wax paper under something like a brick or a band or what have you.
Some will ooze out or whatever. It shapes very well with coarse sandpaper when you get past the surface skin. Coarse sandpaper is what you want to use on that as well.
It is maybe the filler of choice in ding work, to replace crushed foam, Especially in bigger rail dings (hit by somebody else’s fin, for instance) or breaks, where some foam is compressed and just putting it back together utterly messes up the rocker and alignment. Replace the foam with glue, let cure, sand to shape, glass it with the appropriate resin, done. Way better than the cabosil/aerosil and resin paste we used to use.No need to use splints or replace/repair stringers for anything but cosmetic/psychological reasons.
It is water catalysed, moisture makes it go off. To store it, squeeze out all the air in the glue bottle and cap tightly, otherwise the humidity in the air is enough to ruin the stuff left in the bottle.
hope that’s of use
.doc
Some good info there, thanks Doc.
I’ve cut slots to fit splints to the stringer, so I’ll continue with that for psychological reasons. 
Now back to the shed to squeeze the air out of the glue bottle…
Although it is a very good glue option, it is not the ‘ding filler of choice’. First off, it is a pain in the ass when it comes to sanding between glue and foam; usually there will be a depression between the glue/foam line. Second, there are other better options when it comes to ding filler. 1. More foam, 2. Qcell/cabosil filler and #3, my personal favorite: 2 part pour foam. 3. Gorilla glue usually has huge bubble holes, which will need to be filled (with what, more GG?).
If you’re going to use gorilla glue as a ding filler, don’t hesitate to use bondo as a filler as well.
Lol! Have had boards with mucho bondo brought to me to repair. I’ve got one in the shop now. The owner thinks I am gonna restore his garage find $150 Valley Isle. He is wrong.