How to Take Off Wallpaper from Plaster by Soaking and Scraping
Soak the surface with a wallpaper remover solution.
Although a paintbrush works, the most effective way to get the solution on the wall and not all over the floor is to use a paint roller or a spray bottle.
Don’t wet an area larger than you can scrape off within about 15 minutes.
Scrape off the wallpaper.
Use the wallpaper razor to scrape off the sodden paper and let it fall to the floor (which you’ve already covered).
Peel away larger sections of paper that have been softened up.
Once you have a large section softened and raised, you can grab hold and peel.
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.