To remove wallpaper paste, apply hot water to the paste to soften the material, scrape the paste from the wall with a putty knife that has rounded corners, and remove any remaining paste with a gel stripper. A light sanding may also be necessary for best results.
- Soften the paste
Soften any wallpaper backing with hot water. Make the hot water as hot as you can touch without causing burns. To soften the wallpaper paste, allow the water to sit for 15 minutes, holding the bit of backing in place, until the backing can be peeled using a fingernail. If necessary, repeat the process several times. Work with only a small area of the wall at a time to avoid letting the paste harden again.
- Strip the paste
Scrape off the leftover backing and wallpaper paste with a flexible-bladed metal putty knife. Use a knife with rounded edges to avoid gouging the wall. Remove as much of the backing and paste as possible without digging into the surface of the wall beneath. Then, move on to an adjacent wall area.
- Apply the gel
Locate any remaining traces of wallpaper paste by spraying the wall with a mist of water and shining a flashlight onto the wall to note any irregularities. Spray any remaining wallpaper paste with gel wallpaper stripper, and let it sit on the paste for about 15 to 20 minutes to work its way through. Scrape off the gel and paste with the putty knife, and then rinse off the wall with clean water to remove any residue.
- Sand the wall
Remove any lingering bits of wallpaper paste by sanding them off with a hand sander and 120-grit sandpaper. This prevents future paint jobs from flaking or bubbling.