How to Sand Wood Trim and Molding Before Painting (120–320 Grit Guide)

Painting trim and molding gives any room a polished look, but the secret to crisp, professional results lies in proper sanding. By preparing the surface with the right grit sequence, you’ll achieve paint adhesion that lasts and a finish that looks smooth to the eye and touch.

Why Sanding Trim Matters

Trim and molding often have small dents, brush marks from old paint, or glossy finishes that resist new paint. Sanding dulls the surface, smooths imperfections, and creates a profile that allows primer and paint to bond effectively.

Best Sandpaper Grits for Trim & Molding

• 120 grit: Removing old brush marks or uneven paint.
• 180 grit: General smoothing and leveling.
• 220 grit: Preparing bare wood or primer for painting.
• 320 grit: Final light sanding before applying finish coats.

Tools You’ll Need

• Sandpaper sheets (120–320 grit).
• Sanding block for flat sections.
• Sponge sander for curved molding.
• Tack cloth or microfiber rag for dust removal.

Step-by-Step: Sanding Trim and Molding

1. Prep the surface. Clean trim with mild soap and water, then let dry.
2. Level rough areas with 120 grit. Use 120 grit (25-pack) to smooth heavy brush strokes or uneven spots.
3. Smooth with 180 grit. Switch to 180 grit (50-pack) for even surface preparation.
4. Refine with 220 grit. Apply 220 grit (100-pack) to ready the surface for primer or paint.
5. Finish with 320 grit. Use 320 grit (25-pack) before final coats for a flawless smoothness.

Special Cases

For pre-primed trim, start at 220 grit to scuff the surface lightly. For raw wood trim, work through the full sequence from 120 to 320 for best results.

Pro Tips

• Sand with the grain to avoid scratches showing through paint.
• Use a sponge sander for detailed moldings to reach contours evenly.
• Vacuum dust before applying paint—dust particles ruin smooth finishes.

Aftercare

• Let paint cure fully before cleaning trim.
• Use gentle cleaners to avoid damaging fresh paint.
• Touch up chips promptly by lightly sanding and repainting.

FAQs

• Do I always need to sand trim before repainting? Yes, even a light sanding improves adhesion.
• Can I skip primer on trim? Not recommended—primer ensures paint bonds and prevents bleed-through.
• What grit is best before the final coat? 320 grit for ultra-smooth results.

Watch & Learn

Get the right grits for trim sanding: Stock up on 120–320 grit sheets in 25, 50, and 100 pack options. Shop fine sandpaper.