Vinegar makes a great solvent for wallpaper paste. Just dilute 1 cup (225ml) of white vinegar with 2 quarts (2-3 liters) of very warm water, and apply generously with a sponge. Once you get an edge or corner of the wallpaper to lift, then start working the vinegar solution behind the paper to break down the adhesive. This process is most effective when you keep your work area very damp-let the warmth of the water and the chemical properties of the vinegar do the work for you. Rinse your sponge often mix a new batch of vinegar-and-water solution when it becomes cool and/or murky. The bonus is that vinegar is inexpensive and it will not stain or discolor carpeting or other flooring.