How to Take Off Wallpaper from Plaster by Soaking and Scraping
After the wallpaper is taken off, wash the walls with a remover solution.
Wash off any remaining adhesive residue with remover solution or with a nonphosphate cleaner in water, using a large sponge or sponge mop.
You can use an abrasive pad or steel wool to help you remove the adhesive residue on plaster, but use caution on drywall. Avoid overwetting or abrading the paper facing.
Rinse your sponge often in a separate bucket of water, squeeze it out, and continue rinsing your walls until all the residue and remover solution are gone.