I am stripping wallpaper border in the middle of the wall all around the room. It has stripped off the wallpaper and 2 layers of paint. Part of the paint is flaking off once i use a scraper on it. What's the best thing to do? As it's not the whole wall is just in the middle of the wall on all the walls in the room. It has come up patchy, with parts of old paint, and through to plasterboard. What is the best solution before I start painting the walls? Can I sand the edges and use primer and paint Or use easi fill and sand and paint. If prime what the best to use? Could I water down contract matt paint from valspar?