: One thing I'm doing that might be a (or the) problem is that after I lay the
: glass on, I'm putting a layer of wax paper between the wet glass and the
: bag-o-sand. Is that causing a problem?

You definitely need a fillet around the gasket, as the others said.

I doubt the wax paper is the cause of any of your grief. For both of my lips, I laid a sheet of clear plastic (much heavier than saran) over the top of the glass & epoxy, before putting the sand down. My first attempt (the forward hatch lip) was no great success, but still usable. For my second lip, I tried to press out as many bubbles and as much excess epoxy as I could with my fingers, after laying down the plastic release sheet, but before putting the wet sand down.

There were far fewer bubbles, gaps & wrinkles in my second lip, but they weren't eliminated entirely. There were still a few bubbles around the edge of the gasket, which I just filled with thickened epoxy before scraping out the sacrificial gasket.

They don't exactly look professionally made, but they work.

Ken