Sanding Hardwood Floors Between Finish Coats (220–400 Grit Guide)

Even perfectly applied floor finishes develop small bubbles or raised grain between coats. Light sanding between layers ensures your hardwood floor cures flat, glossy, and free of rough patches. This guide walks through the correct grit sequence and sanding method to achieve a smooth, professional-grade finish without cutting through the protective layers.

Why Sanding Between Coats Matters

Each coat of polyurethane or varnish leaves behind microscopic texture, dust nibs, or slight unevenness. Sanding between coats smooths these imperfections and creates mechanical adhesion for the next layer. Skipping this step can lead to peeling, dullness, or visible texture once the floor cures.

Recommended Tools

• Orbital floor buffer or pole sander with fine screen.
• Wet/dry sandpaper (220–400 grit range).
• Vacuum with fine filter and tack cloth.
• Microfiber mop and clean rags.
• Protective finish: water- or oil-based polyurethane.

Ideal Grit Sequence

• 220 grit – Knock down grain and bubbles after first coat.
• 320 grit – Refine surface for smoothness before next coat.
• 400 grit – Optional ultra-smooth sanding for high-gloss finishes.

Step-by-Step: Sanding Between Floor Coats

1. Allow full dry time. Wait at least 24 hours for oil-based or 6–8 hours for water-based finishes. The surface must feel hard and dry before sanding.
2. Initial leveling. Use 220 Grit (25-pack) paper or a sanding screen on a buffer to flatten dust particles and raised fibers. Work in the direction of the wood grain with light, overlapping passes.
3. Surface refinement. Switch to 320 Grit (50-pack) to refine the sheen and ensure a consistent feel across the floor. Vacuum frequently to prevent grit buildup underfoot.
4. Optional final smoothing. For mirror-like gloss, finish with 400 Grit (100-pack) paper. Sand gently and evenly, then wipe with a damp cloth to remove all residue.
5. Clean thoroughly. Vacuum, tack-wipe, and inspect under side lighting to confirm no dull patches or residue remain before recoating.
6. Apply next coat. Use a clean applicator and steady strokes along the grain. Avoid overworking the finish—let it self-level.

Special Cases

For matte or satin finishes, stop at 320 grit—over-sanding can reduce adhesion. For high-traffic floors, consider a light scuff before the final coat rather than full sanding to preserve finish thickness. If bubbles or uneven sheen persist, extend dry time between coats for better leveling.

Pro Tips

• Use pole sanders for easy control and even pressure.
• Keep floors dust-free—any grit left behind will scratch the next coat.
• Change sandpaper frequently; worn sheets can glaze and create swirl marks.
• Always work with good ventilation to help finish cure evenly.
• Don’t walk on freshly sanded floors with dirty shoes—dust transfers easily into wet finish.

Aftercare

• Allow the final coat to cure for at least 72 hours before heavy traffic.
• Place felt pads under furniture legs to prevent scratches.
• Clean with non-abrasive, pH-neutral floor cleaners.
• Rebuff and recoat every 3–5 years to maintain gloss and protection.

FAQs

• Do I need to sand between every coat? Yes—light sanding promotes adhesion and eliminates imperfections for all but the final layer.
• Can I skip sanding if I recoat quickly? Only for specific water-based finishes that allow chemical bonding within 2 hours—always check the product label.
• What if I sanded through a coat? Spot touch with the same finish and let it level before reapplying the next coat.

Watch & Learn

By gently sanding between coats with 220–400 grit, you’ll achieve that coveted glass-flat hardwood finish—free of bubbles, bumps, and dust marks—for floors that feel as smooth as they look.