The previous owner of my 1920s bungalow drywalled over a bunch of the original windows (!) and I'm trying to uncover and restore them to let some more light into the cavelike parts of the house. There's an exterior window installed over one of the windows; it's a bubbly-textured glass with some sort of shiny black coating painted onto it. I've tried every chemical paint remover that I have - hot vinegar, acetone, oven cleaner - and the coating won't budge. The coating is on the bubbly textured side of the glass so I've had no success scraping or sanding it off. I'm pretty sure it's a coating since I can see unevenness and stroke texture in it from the inside when the sunlight shines through.
Anyone have any idea what this might be and what would take it off? I'd rather not rip the window out entirely if I don't have to.