The best way to deal with wallpaper
paste on wallcovering is to not get it on the surface in the first place. If you are a do-it-yourselfer, make sure to wipe down the wallpaper sheets several times with clear water during the hanging process. If you (or a careless paperhanger) got paste on the surface you should place a paper towel over the dried paste and spray the towel with Windex. (Do not let the Windex drip down the wall from that spot.) Let it soak for 10 minutes or so and carefully dab the spot after the paste has softened. Be advised that some wallcoverings, particularly dark papers, will "burnish" or leave a shine mark if you rub. The best way to proceed with this type of cleaning is to get a test piece if possible before you attempt to clean a surface.