Spackle is a type of adhesive repair compound. Spreading spackle over small holes, nail heads, cracks, seams and gaps conceals the imperfections. Spackle is available as premixed or powered. Adding water to the powered variety creates thick spreadable slurry. Spackle sets as a hard and durable patch. Spackle adheres well to both a drywall ceiling and a cement board ceiling. Applying spackle to a ceiling creates a defect-free surface ready for paint or other finishing materials.
Mix powdered spackle with water according to the label directions in a bucket or use already mixed spackle. Scoop spackle out of the bucket and load it into a small rectangular low-sided plastic container with a spackle knife.
Gain access to the ceiling with a scaffold or stepladder.
Dip a 5-inch spackle knife into the spackle loading half the width of the blade. Straddle the spackle knife blade over hole, seam, nail head or crack. Hold the spackle knife almost perpendicular to the ceiling with the blade facing you. Press the spackle into the imperfection and push the spackle knife away from you depositing spackle on the ceiling. Reload the knife with spackle as necessary. Skip to step 6, if you are filling nail heads, holes or cracks.
Align one end of specialized perforated paper tape with the end of a seam. Center the tape across the seam. Drag a clean 5-inch spackle knife over the tape, embedding it in the spackle smoothly.
Scoop up spackle with an 8-inch spackle knife. Position the spackle knife over the first layer of spackle almost perpendicular to the ceiling with the blade edge facing you. Press the knife to the ceiling and push it along over the tape depositing a thin layer of spackle. Scoop up spackle with a 12-inch spackle knife and apply using the same method as for the other size spackle knives deposit spackle over the previous layer of spackle. Using progressively wider blades creates thin edge over the seam that is easy to blend with the ceiling. Allow the spackle to dry fully, generally three to four hours.
Insert 100-grit sandpaper onto a drywall-sanding plate. Attach the sanding plate to a swivel-mount pole. Sand the surface of the spackle smooth and level with the drywall surface.