The chemical known as liquid sandpaper may cause some slight confusion since no sanding is necessary when using it. In fact liquid sandpaper is an easy alternative to sanding if you have a paint job you need to get done quickly. If applied correctly, liquid sandpaper will remove the outer layer of gloss from a painted surface, creating a coarse and rough surface necessary for a new coat of paint to stick to a wall.
Wash the wall you want to paint with warm water and a small amount of soap. Dish soap or hand soap is sufficient. Make sure that you completely remove any dirt from the wall.
Dry the wall completely with a clean cloth. Any residue moisture could affect the effectiveness of the liquid sandpaper, so be diligent during the drying process. You can also allow the wall to dry on its own.
Use a lint-free cloth to apply the liquid sandpaper. Place the liquid sandpaper on the cloth, and rub it on the areas you want to be "sanded."
Let the liquid sandpaper sit on the wall for the time specified on the directions. The time necessary for the liquid sandpaper to wear away at the outer layer of gloss may vary depending on the brand.
Dry the surface with another clean, lint-free cloth, or wash off the liquid sandpaper. Read the directions on the bottle because different brands of liquid sandpaper have different removal directions.