How to Sand Drywall Joints Smoothly Before Painting

Drywall finishing is all about the joints. Even if your drywall sheets are installed perfectly, poorly sanded seams will show through paint and ruin the look. With the right sanding sequence and tools, you can achieve invisible joints that blend seamlessly with the rest of the wall.

Why Sanding Drywall Joints Matters

Joint compound, or "mud," is applied to cover seams and screws. Once dry, it leaves ridges and imperfections. Sanding levels the compound, feathers edges into the drywall, and preps the surface for primer and paint. Skipping this step will result in visible lines and rough patches.

Essential Tools

• Drywall sanding pole or hand sander
• Dust mask and goggles
• Vacuum with HEPA filter
• Tack cloth or microfiber rag
• Silicon carbide sandpaper sheets (various grits)

Best Grit Sequence for Drywall Joints

• 120 grit: First pass to knock down ridges.
• 150 grit: Smoothing and blending into drywall surface.
• 220 grit: Final pass for a flawless finish before primer.

Step-by-Step: Sanding Drywall Joints

1. Knock down ridges. Start with 120 grit (25-pack) to remove dried mud lines and raised edges.
2. Feather the edges. Use 150 grit (50-pack) to blend compound smoothly into the drywall surface.
3. Perfect the finish. Switch to 220 grit (100-pack) for a silky surface ready for primer.
4. Clean thoroughly. Vacuum dust and wipe with a tack cloth to avoid residue under paint.
5. Check under light. Shine a work light across the wall—shadows reveal imperfections that need touch-up sanding.

Special Cases

For corners, fold sandpaper to maintain crisp lines. On ceilings, use a sanding pole to reduce fatigue. If you’re repairing old walls, you may need to repeat sanding after a second coat of joint compound.

Pro Tips

• Keep sandpaper flat to avoid gouges.
• Work in sections, not the entire wall at once.
• Always sand in a well-ventilated area.

Aftercare

• Store leftover sandpaper flat and dry.
• Rinse tack cloths for reuse.
• Prime immediately after sanding to seal the surface.

FAQs

• Can I use a power sander on drywall? Yes, but keep it light—too much pressure can damage paper facing.
• Do I need to sand between primer coats? A quick pass with 220 grit ensures a professional smoothness.

Watch & Learn

Sanding drywall joints is the key to a professional finish. Stock up on the right grits from our drywall sanding collection and make every wall paint-ready.