To remove wallpaper paste residue, soak the wall with a liquid wallpaper removing product or a gel stripping agent, then pull up the residue with a putty knife. Some modern wallpaper products can be peeled away from the wall with no leftover residue, but older wallpaper requires more time and effort to remove.
After removing wallpaper, traces of adhesive might remain on the drywall or plaster. The gel stripping agent is best for drywall, as it causes less damage to the surface than a liquid product.
Step 1: Remove the wallpaper
Removing the adhesive is easiest after all the wallpaper has been stripped from the walls. This includes both the paper facing and the backing, which can be removed separately. Using a sponge, apply a commercial wallpaper removal product for drywall or extremely hot water for plaster, then peel away the paper.
Step 2: Apply the stripping agent
Most gel strippers come in a spray bottle. Spray all wallpaper paste residue with the stripping agent, then let it sit for 15 minutes before wiping or scraping it off. If a stripping agent is not available, this step can also be accomplished with wallpaper remover, though it might take more time. Rinse the wall with cool water to complete the job.