The ronseal one coat damp seal permanently blocks damp stains on walls and ceilings you can even put it onto damp walls it lets trapped moisture escape without causing anymore damage when its dry you can paint or wallpaper over it before you start make sure the cause of damp has been fixed open your doors and windows for ventilation and put down dustsheets to protect anything you dont want to get paint on preparation remove any wallpaper with a scraper and sand off any loose or flaking paint mak