How to repair drywall and hide the repair
More important that knowing how to repair drywall is knowing how to make the repair invisible.
The first step in making a drywall repair on a painted wall or ceiling is the repair. But even if you know how to repair drywall expertly – the repair is properly feathered out, the bump is minimal and there are no taping tools marks or scratches left from sanding – the repair will stand out.
The problem is that the repaired area is now too smooth. The painted surfaced surrounding the repair has a slight texture because of the texture created when painting multiple times with a paint roller. This smooth repaired area will likely show through even after priming and painting.
The degree of the problem will depend on the sheen and color of the paint, as well as the angle and amount of light.
When choosing paints, keep in mind that glossier paints highlight any differences in the painted surface. Flat paints are best at concealing minor differences. Even eggshell sheen paints, which are sometimes sold as a washable flat paint, have enough sheen to highlight the differences in the surface. Deeper colors such as red and blue really highlight surfaces differences while gray paints are good at hiding them.
Lighting also adds to the problem. A well-lit surface, particularly one that is cross lit, will emphasize the different texture created by the repair.
The customer may also be part of the problem. Because the customer knows where the repair is they tend to focus on that precise area when inspecting the paint job. They often look for the exact angle and even time of day when the repair is most noticeable.
How to repair drywall so it doesn’t show
To truly hide the repair, you either have to make the repaired surface texture match the painted surface texture or make the painted surface texture as smooth as the repaired surface.
If the painted surface has only a slight texture, applying two coats of primer with a paint roller will often do the trick. The primer will help equalize the differences in absorption between the two surfaces, which will also help hide the repair.
After priming, the entire wall or ceiling will have to be painted with at least one coat of paint. Spot painting will seldom do the trick. As mentioned earlier, if you’re working with paints with greater sheens or deeper colors the repair will be more difficult to conceal so an additional coat of paint may be necessary.
For the most invisible patch, especially when working with a customer who does close inspections, your best option is to skim coat the entire wall or ceiling or at least a large part of the area with a thin coat of the same joint compound used in the repair.
The skim coat will accomplish two things. It will make the entire surface equally smooth and it will equalize the absorption of the surfaces. Then once the area is primed and painted, the repair will be invisible. It sounds like a lot of work, but actually, a skim coat is very easy to apply.
Sand the entire surface with a 220 grit sandpaper. This will smooth out the painted surface a little more and remove any little raised imperfections in the paint such as bits of dirt or tiny chips of paint.
Thin down the drywall compound that you used to make the repair slightly, using about 4 cups of water in a 5-gallon bucket of compound.
Use a 9-inch paint roller with a ½-inch nap cover to roll the compound over a section of the wall or ceiling that is no larger than about 3 feet by 8 feet. If you try to roll a larger area, the compound will start to dry before it can be removed.
Using a 12-inch-wide taping knife, remove the compound leaving only a thin film of compound on the surface. This thin “skim coat” will be just enough to fill in the texture of the painted surface so the entire surface will be consistently smooth.
As you remove the compound, put it in a taper’s pan. Then it can be dumped back into the bucket of compound. Continue this until the entire wall or ceiling has a skim coat.
If you do it carefully with good lighting on the area as you work, the result will be a smooth surface that will require very little sanding.
When the skim coat is dry, lightly sand it using a 220 grit sandpaper. There’s no need to remove the dust from the surface. It’s not necessary because the primer will absorb the dust, and you risk marking up the rather soft compound if you try to remove dust with a broom or even a damp sponge.
Prime and paint.
−By Myron Ferguson, Ferguson Drywall Innovations, Middle Grove, New York