From what I'd read on this Forum, I was under the impression that epoxy would not stick to Plexiglas, at all. Did I read the above post correctly???
It actually stuck to the Plexiglas?
My first glass cloth backed butt joint was done using wax paper. It worked fairly well, but I had problems with the wax paper sticking to the epoxy. I put that down to the fact I was building in the garage with 90*+ temps outside, no idea how hot it got inside, but it was like an oven. I thought that the heat of the room combined with the heat of the curing epoxy had melted the wax.
It did take a little extra work to sand that wax paper off, but no real problem. So the rest of my butt joints were made using some thick plastic bags that were meant for shipping live fish. a few cuts with a razor knife and they were opened up flat, and just big enough for the job.
So far, the epoxy has not stuck to that, at all. There were a few places that had some wrinkles from the bags that had to be sanded down, again just a little more work, but no real problem.
Piper's suggestion of using dish soap to keep the epoxy from sticking to the Plexiglas sounds like it would work, but I don't see how it would be possible to make a FG tape-backed butt joint that way. At least, not the way I made the joints.
I laid the plastic sheet down, then laid a piece of the tape on it and wetting it out with epoxy, spreading the epoxy off the tape a couple of inches on both sides. Next, the two pieces to be joined, the joint area already having been lightly sanded was laid on top of the wet tape, then another piece of tape was wetted out on top of the seam. Another layer of plastic sheeting across that, and the next two pieces of ply being joined was lined up and laid on that, tape on top, and another layer of plastic.
A piece of ply on top of that, then a weight just heavy enough to hold it all flat was used.
This is basically how I did both of the side panels at once, in sort of a "sandwich." The advantage was in getting both panels done at once, and there was no having to turn a joined panel over with only one side taped and glued, and then doing the other side.
So if epoxy does bond with Plexiglas, then I guess I'd have to keep using the plastic sheet on the next build, and just live with having to sand down a few epoxy wrinkles.
The above method of making several butt joints at once was shown in a very nice diagram about half-way down the first page of
THIS THREAD. The glass-backed butt joint and other methods of joining sheets of ply was fairly well covered in it.
Mike S.
Spring Hill, FL
