Nail holes, small cracks, and gouges in drywall are filled with spackle or joint compound, sanded smooth, and painted. This technique works for damage under 1 inch; larger cracks require tape and multiple coats.
Fill a nail hole in an inconspicuous area. Sand it level. Apply a second coat if needed. Paint to match the wall. Practice on several holes to develop judgment about filling thickness and sanding technique.
From your study of interior finish damage types, you know how to identify the character of wall damage — whether a nail hole, a crack, a gouge, or something larger — and understand what caused it. Filling and finishing is the next step: the repair technique that makes that damage invisible. The core challenge is not the filling itself, which is simple, but the finishing, which requires understanding how fill materials behave as they dry and how to blend the repaired area seamlessly with the surrounding wall texture and paint.
Spackle and joint compound are the two primary fill materials, and they behave differently. Lightweight spackle dries quickly (30-60 minutes) and is ideal for small holes under half an inch — nail holes, picture hooks, small dings. It comes pre-mixed, shrinks minimally, and sands easily. Joint compound (sometimes called "mud") dries more slowly (overnight), shrinks more as it dries, and is better suited for larger repairs and any area that will be taped. For nail holes, spackle is almost always the right choice. The key rule is this: expect shrinkage. Even spackle shrinks slightly as moisture evaporates. A fill that looks level when wet will typically show a slight divot once dry, requiring a second thin coat. Applying one thick coat and hoping for a flat result is the most common beginner mistake.
The application sequence builds from the inside out. For a nail hole, the approach is: apply a thin first coat slightly proud of the surface (slightly above flush), let it dry completely, sand lightly with 120-grit sandpaper until level, apply a thin second coat if needed to fill any remaining divot, dry again, sand with 220-grit for a smooth final surface. Feathering — gradually thinning the compound out over a wider area around the repair — is the technique that makes a patch blend invisibly. A hard edge at the perimeter of a patch reads as a visible bump when light grazes the wall. A feathered edge transitions gradually enough that the eye doesn't detect it.
Paint matching completes the repair, and from your study of paint product selection you know that sheen level and color must both match. A patched area painted with flat paint on a wall finished in eggshell will show the repair even if the color is perfect — sheen difference creates visible texture variation in raking light. Test paint compatibility: prime the patch first (especially over spackle, which is highly absorbent and will cause paint to dry to a different sheen than the surrounding wall). Apply paint in thin coats using the same application method as the original finish. For repairs in high-traffic or high-visibility areas, feathering and priming are not optional steps — they are what separates a professional-looking repair from one that is immediately visible to anyone who knows what to look for.