Spackling or "mudding" is used to cover up cracks, joints, corners, and damage in drywall. Although spackling only requires simple tools, smoothing out the mud correctly requires some skill. Spackling inside and outside corners pose an additional challenge. Follow these tips for spackling the outside and inside corners of drywall.
General Spackling Tips
When mixing spackle, blend thoroughly with an electric mixer. Add enough water to make the consistency like a smooth peanut butter. Avoid leaving unmoistened powder in the mix or it will not adhere to the wall.
Start with spackling the nail and screw holes, then move on to the long horizontal joints, then the outside corners, and then finish with the inside corners.
Make sure you allow enough time to dry in between coats. If the spackle is grey, it is still drying. Once it turns white, it is completely dry.
In cold climates, run a fan or heater to speed up the drying process.
For all spackling tasks, purchase a variety of different sized putty knives. For spackling corners, an 8-inch, 10-inch, or 12-inch can do the job.
Don't forget to purchase an inside corner tool!
Outside Corner Spackling Tips
Aim to finish outside corners in three coats.
The first coat should be the heaviest. Use an 8-inch knife to apply the mud, covering up and filling in the space between the wall and the corner bead.
Position the putty knife so that one edge of the knife is on the corner bead and the other end over the drywall.
On the second coat, use a larger knife (a 10-inch works well).
Finish off with a third coat by smoothing out the edges so that they are invisible, using a 12-inch knife.
Inside Corner Spackling Tips
Inside corners include the joint connecting the ceiling and wall.
Start by applying a thick layer of spackle with an 8-inch knife. Smooth out immediately using an inside corner tool. An inside corner makes the job much easier!
Continue to make long passes with the inside corner tool, starting at the top and working down.
On the first coat, focus on the corner, don't worry about the edges. These can be smoothed out with the next couple of coats.
Ideally, the corner joint should be finished by the end of the first coat. Sand the edges lightly in between each coat.
Add more mud to the edges of each side of the corner with an 8-inch knife for a second and third coat. Feather outward to make the edge invisible.
Keep applying coats and sanding until each joint is unnoticeable. Don't stop spackling and sanding until the joint edges are invisible.
Taking the time to smooth out your mud job will create a great finished look. Add texture to match the existing wall if applicable. With the right tools and technique, the imperfections in drywall will disappear after spackling, texturing, and painting.