Applying a drywall patch leaves a spot on the wall that doesn't match the original texture. This will be obvious in good lighting and will become even more noticeable when you paint over the area. There are three basic wall textures that are probably on your wall. The first is just from the nap of the paint roller and is smooth with little variation. The next is a knock-down which has little stipples of texture that have been slightly flattened. The last one is orange peel, which is a consistent amount of tiny bumps scattered on the surface. Match the texture on the wall before you paint.
Things You'll Need
Damp sponge or tack cloth
6-inch drywall blade
Spray texture in knock-down
Spray texture in orange peel
Paint roller with nap that matches
Sand the drywall to feather out any edges and make it smooth and flush with any existing wall. Wipe off the dust with a damp sponge and let it dry for an hour. You can also use a tack cloth, which is slightly sticky, to blot up dust. You do not need to wait for an hour if you use the tack cloth.
Spray the knock-down texture if the wall has slightly flattened variegation on the surface. The spray can be found in hardware stores. Spray it 24 inches away from the wall. Wait half an hour for it to partly dry and gently drag the drywall blade at a slight angle down the length of the area. Try to make a smooth motion and do not pick up the blade or it will produce uneven skips in the finish. Let the texture dry for at least an hour before painting.
Apply orange peel texture in a smooth up-and-down spraying motion. The orange peel is a much more textured surface, with many bumps. The spray will apply the texture for you, but you control how much. If the wall you are trying to match has many bumps, apply a thick coat. A lighter, quicker application will provide less texture. It is best to start light and add more if needed. Allow an hour to elapse for drying.
Paint on primer with a roller in the nap that matches your wall. There are many thicknesses to choose from and there are also special texture rollers. If you did not apply any previous paint, you will have to guess. A medium nap will match closely unless there is a specialty texture on the wall. Roll in a smooth up-and-down motion. Allow the primer to dry for an hour or the amount of time specified on the paint can.
Lay out a drop cloth to protect the floor. Pour sheetrock mud into one-third of the bucket. Put the mixer bit on the drill and put the end of it into the bucket. Turn it on and gradually add water until the mud is the consistency of a thick milk shake. Add dry mud if it gets too thin.
Pour the sheetrock mud mix into a paint pan. Coat a paint roller in mud and roll it on the wall. Use smooth, even strokes. The slower you roll, the higher the texture will be. There is no right way to do this; it depends on what look you like. Start in one corner and work across the wall.
Create more texture by rolling across what you have done. The roller will remove some of the mud and minimize the look. You may have to add water to the main batch of mud as you work, since it will harden. The texture will also be dictated by the thickness of the nap on the roller. Thicker nap yields higher variations on the wall.