Sanding Drywall Before Painting: Smooth Walls Made Simple

Nothing ruins a fresh paint job like visible seams, ridges, or rough patches on drywall. The secret to silky, professional-looking walls is proper sanding before painting. Whether you’re finishing new drywall or repairing old walls, this guide shows you how to sand drywall step by step using the right grit sequence and tools.

Why Sand Drywall Before Painting?

Drywall compound (mud) shrinks as it dries, leaving ridges and uneven areas. Sanding flattens these imperfections and blends seams into the wall so they disappear under paint. Skipping sanding leads to visible tape lines and a rough finish that even the best paint can’t hide.

Recommended Tools

• Pole sander or sanding block for flat walls
• Corner sanding sponge for inside angles
• Vacuum or shop vac with dust attachment
• Respirator, safety glasses, and drop cloths

Choosing the Right Grit Sequence

• 120 grit: Initial sanding to knock down high spots and rough seams.
• 180 grit: Refining and blending patched areas.
• 220 grit: Final pass before priming for a smooth surface.

Step-by-Step: How to Sand Drywall

1. Prepare the area. Seal off doorways and vents to contain dust. Lay down drop cloths.
2. Start with 120 grit. Level ridges and rough areas using 120 grit (25-pack). Use a pole sander for large surfaces and apply light pressure.
3. Switch to 180 grit. Smooth seams and feather edges around patches. Try 180 grit (50-pack) for even blending.
4. Finish with 220 grit. For a paint-ready surface, lightly sand the entire wall using 220 grit (100-pack). Focus on transitions between drywall and mud.
5. Vacuum and wipe down. Use a shop vac and tack cloth to remove dust before priming.

Special Cases

Ceilings: Always use a pole sander overhead and keep pressure light to avoid gouges.
Skim-coated walls: Require extra passes with 220 grit for uniform smoothness.
Repairs over glossy paint: Use 120 grit to scuff the surface before mudding.

Pro Tips

• Work under bright light to spot imperfections.
• Keep sandpaper fresh—clogged paper scratches instead of smoothing.
• Always sand in circular or overlapping motions for even results.

Aftercare & Next Steps

• Prime walls immediately after sanding to seal drywall dust.
• Use a high-build primer for problem areas with minor scratches.
• Store leftover sandpaper flat and dry for your next project.

FAQs

• Do I have to sand after every coat of mud? Yes, but lightly—focus on ridges and feathering edges.
• Can I use power sanders? For large jobs, yes, but keep them on low speed to avoid gouging.
• What happens if I skip sanding? Seams, tape lines, and bumps will show through paint.

Watch & Learn

Sanding drywall is dusty work, but with the right grits and techniques, your walls will look flawless once painted. A little patience now saves hours of frustration later—and ensures your finish is smooth and professional.