Our house is about 90 years old. Back in the day they applied this "wallpaper" to help prevent the plaster from cracking. In one of my bedrooms I am redoing it is all coming away from the walls and leaving areas I don't know how to fix. I have scrapped away as much as I could but there are rough edges. Not sure if I need to plaster over these area's (some very large ones) or just sand down the rough areas as best I can and then repaint. There are some cracks that have become exposed, but the plaster is otherwise intact! HELP!!!!!!!!!!!