How to Sand Drywall Joints for a Perfectly Smooth Wall (120–400 Grit Guide)

When finishing drywall, sanding is the critical step that separates a professional-looking wall from one full of seams and imperfections. Done correctly, sanding creates a flawless surface ready for primer and paint. This guide covers the grit sequence, techniques, and pro tips to help you achieve a perfectly smooth wall.

Why Sanding Drywall Matters

Even the best taping and mudding work leaves slight ridges, bumps, or uneven seams. Sanding levels these surfaces so paint applies evenly. Skipping or rushing this step results in visible lines, rough patches, and uneven finishes under paint.

Tools You’ll Need

• Drywall sanding pole or hand sander
• Vacuum or dust control attachment
• Respirator mask and goggles
• Tack cloth or microfiber cloth
• Wet/dry sandpaper sheets (120–400 grit)

Recommended Grit Sequence

• 120 grit: Initial leveling of joint compound and seams.
• 180 grit: Refining after first sanding pass.
• 220 grit: Smoothing before primer.
• 320–400 grit: Optional ultra-smooth finish for glossy or dark-colored paints.

Step-by-Step Process

1. Inspect the surface. Shine a work light across the drywall to highlight imperfections.
2. Start with 120 grit. Sand joints, screw spots, and ridges. Use a sanding pole for broad areas and a hand sander for edges.
3. Move to 180 grit. Smooth transitions between mudded seams and bare drywall.
4. Refine with 220 grit. This grit creates a uniform surface ready for primer. For consistent results, use 220 grit (50-pack) sheets that cover large projects efficiently.
5. Optional 320–400 grit finish. For high-end finishes or glossy paints, finish with 400 grit (25-pack) wet/dry sheets for a silky smooth surface.
6. Clean thoroughly. Wipe away dust with a tack cloth or vacuum with a brush attachment. Residual dust will ruin primer adhesion.
7. Prime the walls. Always use a drywall primer-sealer before painting to lock in the surface and prevent flashing.

Special Cases

For patches or small repairs, start directly at 120 grit (100-pack) and finish with 220 grit. Avoid skipping grits—jumping too quickly can leave scratches that show through paint.

Pro Tips

• Always sand in a circular motion rather than back-and-forth to avoid grooves.
• Keep your work light at a sharp angle to easily spot imperfections.
• Use wet sanding for dust control, especially in occupied spaces.
• Don’t oversand—too much pressure can tear the paper face of the drywall.

Aftercare

• Vacuum the entire room to remove fine drywall dust.
• Wipe walls with a damp microfiber cloth before priming.
• Dispose of sanding dust safely—avoid sweeping which redistributes particles into the air.

FAQs

• Can I use a power sander for drywall? Yes, but use a drywall-specific sander with dust collection. Regular orbital sanders are too aggressive.
• Is wet sanding better than dry? Wet sanding reduces dust but is slower and less effective for large areas. Many pros combine both methods.
• What if I see scratches after priming? Spot sand with 220–400 grit and reprime the area before painting.

Watch & Learn

Whether you’re tackling a single room or finishing a whole house, following the correct grit sequence ensures a flawless wall surface. Stock up on reliable medium grits, fine grits, and super fine grits to cover every stage of drywall finishing.