Very Old Wallpaper Glue on Plaster Walls
I've just removed fabric wallpaper off the plaster walls of an 82-year-old house with little effort. The glue, however, is hardened and brittle. It will not scrape off. It's so hard, I don't know if it will wash off. I'd like to sand it off. Is that an option? Ultimately, I want to paint the walls. I have a large room (13x25), a medium room (14.5x13) and a foyer that has wallpaper on the ceiling(!). Apparently, that was de rigueur at the time (1937). How should I approach this task?