How to Sand Wood Trim and Baseboards for a Flawless Paint Finish (120–400 Grit Guide)

Perfectly painted trim starts with meticulous surface preparation. Even the highest-quality paint can’t hide bumps, scratches, or brush marks from old coats. This guide explains how to sand wood trim and baseboards smoothly, so your next layer of paint or primer goes on evenly and lasts longer.

Why Sanding Trim Is Essential

Trim and baseboards take daily wear—vacuum bumps, shoe scuffs, and layers of old paint buildup. Sanding evens these surfaces, removes gloss, and provides a key for primer or paint to grip. It also prevents the new finish from peeling or showing imperfections under bright light.

Recommended Tools

• Detail sander or sanding sponge for corners.
• Wet/dry sandpaper (120–400 grit).
• Vacuum, tack cloth, and microfiber rag.
• Primer and high-quality trim paint.
• Masking tape and drop cloths.

Ideal Grit Sequence

• 120 grit – Smooth dents, chips, and remove rough paint layers.
• 220 grit – Prepare surface for primer and eliminate visible scratches.
• 400 grit – Final sanding for silky smooth paint finish.

Step-by-Step: Sanding Trim and Baseboards

1. Prep the area. Clean the trim with soap and water, then dry completely. Mask off the wall and floor edges to protect them from sanding dust.
2. Remove rough spots. Use 120 Grit (25-pack) paper to smooth dents, paint drips, or uneven layers. Sand along the length of the trim with gentle, steady strokes.
3. Refine surface texture. Switch to 220 Grit (50-pack) to remove scratch marks and dull glossy areas for primer adhesion. Wipe dust away with a damp cloth before priming.
4. Prime and inspect. Apply a high-adhesion primer. Once dry, lightly sand with 400 Grit (100-pack) paper to eliminate raised fibers or brush streaks.
5. Final painting prep. Vacuum the surface and tack-wipe until perfectly clean. Your trim should now feel smooth to the touch—ready for paint or enamel.
6. Apply paint. Use long, even strokes with a high-quality brush or sprayer. For ultra-smooth finishes, sand lightly with 400 grit between coats.

Special Cases

For stained wood trim, stop at 220 grit before applying stain to maintain proper absorption. For MDF or primed trim, avoid sanding below 150 grit—it’s easy to remove too much material. On ornate molding, use flexible foam sanding pads or folded paper to follow curves and edges.

Pro Tips

• Always sand with the grain or direction of the trim profile.
• Wipe dust frequently—paint won’t stick to a dusty surface.
• Replace sandpaper as soon as it clogs with paint particles.
• Lightly mist the surface when wet-sanding to minimize airborne dust.
• Let primer and paint fully cure before handling to prevent smudges.

Aftercare

• Clean painted trim with a soft cloth and mild soap only.
• Touch up nicks promptly to maintain a clean look.
• Lightly scuff with 400 grit before repainting in the future.
• Avoid abrasive pads or cleaners that dull the finish.

FAQs

• Do I need to sand new trim? Yes—factory-primed trim still has a slick surface that must be dulled for proper paint adhesion.
• Should I sand between coats? For the smoothest finish, yes—lightly sand with 400 grit between coats.
• Can I use a power sander? Yes, but keep it at low speed and use fine grits to avoid removing too much material.

Watch & Learn

Following a careful sanding sequence from 120 to 400 grit transforms old or rough trim into a perfectly smooth base—ensuring your paint glides on evenly and delivers a crisp, durable finish.