Wallpaper glue creates a strong adhesion between the wallpaper and the wall. When you take the wallpaper off the walls, the glue or paste remains behind. The glue needs removed before you paint or add more wallpaper, so you have a smooth surface. Before you can remove the glue, it needs to be saturated with water to loosen it from the walls. Removing the wallpaper paste will require patience, because you need to clean it off in small sections.
Fill a spray bottle or a pump sprayer with hot water. Add 2 tbsp of liquid dish detergent.
Turn off the electricity in the room. Cover the outlets and light switches with plastic.
Place a dropcloth on the floor to catch the wallpaper glue you scrape off the walls.
Wet the area where you need to remove the wallpaper paste. Allow the water to soak for three to four minutes.
Scrape the glue off the wall with a paint scraper or putty knife. Scrape off as much of the paste as possible. Continue to wet the area and scrape until you remove all the paste.
Rinse the wall with clean water. Dry the walls with an absorbent towel.
If you do not have a sprayer, you can soak a sponge in water and apply it to the wallpaper paste to saturate the area.
Wear gloves to protect your hands from any rough surfaces on the walls.