What Sandpaper Grade to Use Before Wall Painting?

About Wall Preparation

• Though you can sometimes paint over wallpaper, the end result will look much better if you remove the wallpaper from the wall, which is a fairly simple task with peel-able wallpapers. Non-peel-able wallpaper may need dampening with water to separate from the wall enough to be peeled away. Soak lightly with a wet sponge, or use a mister to apply water to the surface. Wash the wall with trisodium phosphate, and allow it to dry completely.

Wall Repairs

• Holes from hanging pictures must be repaired with spackle, as well as any small cracks that might be visible on the wall surface. Flaking paint or loose material must also be removed before spackling the area. Running the edge of the scraper over the spackle at a 45-degree angle will make the repair level with the surrounding wall surface. Allow the spackle to dry thoroughly. Careful sandpapering of the area will create a smooth and level work area for painting.

Sanding Glossy Surfaces

• If painting over paints with a glossy finish, roughing up the surface will help the new coat of paint to adhere better. A fine-grain sandpaper is good for this purpose. Washing the wall with trisodium phosphate is another good way to dull down the surface of glossy paint to accept a new coat of paint more securely, according to HomeTips expert Don Vandervort.

Grade of Sandpaper to Use For Wall Preparation

• Careful sanding of repaired surfaces will give the wall a smooth and level surface for a good appearance after paint is applied. Use 100- or 120-grit sandpaper if using wall joint compound and 220-grit paper if using spackle for best results, according to the Canada Home & Mortgage Corporation site. You'll want to wear a respiratory mask when sanding to avoid breathing in abrasive substances. Goggles and gloves should also be used when sanding walls that may be painted with lead paint.

Cleaning and Removing Sanding Grit

• After sanding the wall surface, wipe or vacuum carefully to remove the sanding grit before painting. This residue will show as a grainy appearance if left on the wall and painted over. The brush attachment on your vacuum cleaner is a good way to remove this material from the wall.