Every inch of sheetrock in my house was wallpapered by the original owner without the benefit of sizing being used. So I can't get the paper off without ruining the rock surface. Every time I paint the paper has a tendency to bubble up even though several coats of paint have been applied over the years. In some closet areas the original wallpaper has never been painted over and I am getting ready to paint them. What can I put on the wallpaper to seal it so that the paint does not make it bubble up? BTW, one of my neighbors had the same problem and he solved it by ripping out all the existing sheetrock and putting in new.