Sand Drywall Seams: 120?150?220 Grit Sequence

Perfectly smooth drywall seams are the foundation of flawless walls and ceilings. After taping and mudding, sanding is required to blend seams seamlessly. The proven grit ladder is 120 ? 150 ? 220 grit. This sequence removes ridges, feathers edges, and creates a paint-ready surface.

Why Drywall Sanding Matters

Poorly sanded seams show through paint as ridges or flat spots. Starting too fine clogs paper, while starting too coarse gouges drywall. A balanced progression ensures smooth joints without damaging paper surface.

Tools & Materials

• 9×11 in sandpaper sheets: 120, 150, 220 grit
• Pole sander or sanding block
• Vacuum with drywall attachment
• Dust mask or respirator
• LED work light (to reveal imperfections)

Recommended Grit Sequence

• 120 grit — Removes ridges and high spots in joint compound.
• 150 grit — Refines edges, feathers seams smoothly.
• 220 grit — Final finish for paint-ready smoothness.

Step-by-Step: Drywall Seam Sanding

1. Inspect seams. Shine light along walls to highlight ridges or imperfections.
2. Sand with 120 grit. Use 120 grit (25-pack) to knock down raised areas of compound.
3. Step to 150 grit. Switch to 150 grit (50-pack). Feather seams into surrounding drywall.
4. Final sanding at 220 grit. With 220 grit (100-pack), smooth out surfaces for paint application.
5. Vacuum dust. Drywall dust spreads easily—remove thoroughly.
6. Prime and paint. Apply primer to seal drywall before painting.

Special Cases

Skim-coated walls: May require lighter sanding with 220 only.
Heavy mud ridges: Scrape first, then sand starting at 100 grit.
Repairs: Always sand repair areas slightly wider than patch.

Pro Tips

• Use a pole sander for ceilings to avoid uneven pressure.
• Shine light at an angle—imperfections appear clearly.
• Don’t oversand—going through paper creates permanent flaws.
• Keep strokes light and even to avoid gouges.
• Prime after sanding—paint highlights imperfections if skipped.

Aftercare

• Touch up with 220 grit before repainting in the future.
• Inspect seams annually—patch and sand minor cracks early.
• Store leftover sandpaper for small wall repairs.

FAQs

• Can I start at 220 grit? Not effective—too fine to cut ridges.
• Do I need special drywall sandpaper? Standard fine grits work, but mesh drywall sheets resist clogging better.
• Why not stop at 150? Paint shows scratches—220 ensures professional look.
• Can I wet-sand? Yes—reduces dust but slower, best for small areas.

Video: Drywall Sanding Guide

Closing: With 120 ? 150 ? 220 grit, drywall seams disappear under paint. Careful sanding makes the difference between amateur and professional results.