Before you can paint your room you need to make sure the walls are in good condition. Paint won’t hide cracks, dips, or dents; it will highlight them. And, of course, it will not hide a hole in the wall either. You can find instructions for fixing these problems below.
Large holes in the wall need special attention. Repair procedures differ depending on whether it is an older wall with lath and plaster, or a newer wall using gypsum wallboard (drywall).
Fixing Lath and Plaster Holes
First, clean the hole and the edges of the hole of any debris. The sharp end of a can opener will come in handy here. If the lath is still intact, you can start to fill the hole with compound. You will need to stuff something into the hole to serve as a backing for the drywall compound that will fill the hole if the lath is missing or badly damaged. You can use steel wool or a wad of newspaper. Place the newspaper or steel wool so that it is recessed about 1 inch from the finished surface of the wall.
Alternatively, you can use wire mesh to repair the hole (this works for lath and plaster and drywall). You will need string and a pencil so that you can get it into place behind the hole. Start by placing the pencil in the middle of the mesh and threading the string through the center around the pencil, holding it in place. Next, fold the mesh and insert it through the hole. The mesh will unfold behind the wall. Using the pencil as a handle, pull the string taught so the mesh comes up tight against the back of the hole.
Moisten the edges of the hole with a little water. Using a drywall knife at least 1 inch wider than the hole, spread the compound over the hole. Do this until the compound is about ¼-inch recessed from the finished surface of the wall. Allow this coat to dry until it is tacky. Score this tacky compound with a nail to rough it up so that it will receive the second layer. Let the scored layer dry, then moisten and repeat the process. (Two coats can be used if the hole is less than 4 inches.)
Sand this coat and apply a final coat, sanding this layer smooth with steel wool or a fine-grit sandpaper (100-grit silicon carbide). Use an orbital sander if you have one. To quicken the drying time between coats, direct a fan at the patch. Fast-drying compounds are also available to help speed up the process. Always clean your tools immediately after using this type of compound. Before you paint, be sure to prime any fresh compound after repairing.
Hatch Patch Repair
An alternate method of repairing large holes in either lath and plaster or drywall is the "hat patch" method. This involves cutting a patch that will fit over the hole.
First, undercut the edges around the hole so you have a good clean hole to work with. Again, use the sharp end of a can opener. Tear away a 1-inch strip of drywall paper from around the perimeter so that only the bare gypsum is showing. Use a utility knife to score the drywall paper around the diameter of the cut. This will assure that the hat patch will lie flat, and that there will be no raised edges.
Cut a piece of drywall to the exact shape and dimensions of the total area defined by the bare gypsum. Remove enough of the gypsum from this piece so that you are left with a plug the size of the hole, and a paper brim that will cover the bare gypsum. Apply compound around the hole and insert the patch. Cover the patch with compound. Allow it to dry, and sand it smooth after drying. Apply a second coat of compound (and a third coat if needed), sanding after each coat. Paint the last coat of fresh compound with primer after it has dried.
Cracks are usually simple to repair. Small hairline cracks can be remedied by simply spreading compound over them and sanding them smooth. Larger cracks will need more attention.
To repair larger cracks you will need to first scrape and widen them. Undercut the edges. This can be done with a widening tool or the sharp edge of a can opener. Be sure all the debris is cleaned away. Vacuum out all the dust, as it can cause adhering problems. After you have prepared the crack, dampen the edges before youapply the spackling or drywall compound. If the crack is large enough, over ¾ to ¼-inch, apply a self-adhering fiberglass drywall tape directly to the wall after filling the crack with compound. Do not use the paper tape here, or you will run the risk of the crack appearing again in a couple of months. Apply two coats of compound over the repaired crack with a putty knife, allowing the first coat to dry, then sand and apply the second coat, feathering the edges.
You are ready to spruce the place up with a fresh coat of paint now that you have repaired your walls!