Stains on your wallpaper are tricky to remove. Even if they are successfully removed, the process can discolor or warp the wallpaper. While cleaning products that boast stain removal are intended for hard surfaces, wallpaper requires a mild cleanser to maintain the condition of the paper. A simple method using liquid dish soap can lift stains from wallpaper while keeping the surface intact.
Wipe any surface dust from the wallpaper.
Fill a small bowl with warm water and 1 squirt of liquid dish soap.
Submerge a sponge into the mixture and squeeze out excess water.
Dab an inconspicuous area of the wallpaper to see whether the mixture is safe to use. If so, wipe the stain from bottom to top.
Dip a clean sponge into plain water and wring out the excess. Wipe the stain with the sponge and dry the spot with a clean cloth.