Sanding Between Coats of Paint or Polyurethane: Smooth, Professional Finish

If you’ve ever noticed roughness, bumps, or dust specks in painted or varnished surfaces, the secret to fixing them is sanding between coats. This simple but often overlooked step creates a silky-smooth finish worthy of a professional.

Why Sand Between Coats?

Each coat of paint or polyurethane raises the wood grain slightly and may trap small dust particles. Sanding removes imperfections and provides a light scuff that ensures the next coat bonds properly. Without sanding, the final finish can feel gritty or peel prematurely.

Tools You’ll Need

• 9x11 in sandpaper sheets (wet or dry use)
• Sanding block or sponge
• Vacuum or tack cloth
• Good lighting to spot imperfections

Best Grits for Between-Coat Sanding

• 320 grit: For sanding between coats of primer or base paint.
• 400 grit: For smoothing polyurethane or final coats.
• 600 grit: For ultra-smooth finishes before polishing.

Step-by-Step: Sanding Between Coats

1. Allow the coat to dry. Make sure the surface is fully cured before sanding—usually overnight.
2. Start with 320 grit. Use 320 grit (25-pack) to smooth primer or early coats.
3. Move to 400 grit. Apply 400 grit (50-pack) between polyurethane or enamel coats.
4. Finish with 600 grit. For final passes, use 600 grit (100-pack) to achieve a glassy, touchable surface.
5. Clean the dust. Wipe thoroughly with a tack cloth before applying the next coat.
6. Apply the next coat. Paint or poly will now flow smoothly across the sanded surface.

Special Cases

For high-gloss finishes, wet sanding with 600 grit before the final coat delivers the smoothest results. For matte finishes, dry sanding with 320–400 grit is usually sufficient.

Pro Tips

• Use light pressure—just enough to dull the sheen, not remove the coat.
• Always sand in a clean, dust-free environment.
• Vacuum between every step to avoid contaminating the finish.

Aftercare

• Allow the final coat to cure completely before use—up to 7 days for polyurethane.
• Protect surfaces with coasters and pads to preserve the finish.
• Clean with mild, non-abrasive cleaners only.

FAQs

• Do I need to sand after every coat? For the best results, yes—except the final coat, which should be left untouched.
• Can I sand too much? Yes—avoid cutting through the finish. Use only light pressure.
• Is wet sanding necessary? Only for ultra-smooth, glossy finishes on the last coats.

Watch & Learn

eQualle’s 9x11 in sandpaper sheets make between-coat sanding simple. Available in 25, 50, and 100 packs, designed for wet or dry use. Shop fine sandpaper here.