Refinish Guitars: Sand to 320 Grit Before Sealer

A flawless guitar finish starts with perfect prep. Before spraying or brushing any sealer, the wood must be smooth enough for even absorption but not so polished that it resists adhesion. The sweet spot is 320 grit. Sanding to this level leaves a fine scratch pattern that sealer can grab, ensuring your color coats and clear coats lay flat, bond hard, and shine deep.

Why 320 Grit Matters for Guitars

Unlike furniture, guitars get handled constantly and finished to high-gloss standards. Any scratch or pore telegraphs through. 320 grit balances smoothness with adhesion, preventing both blotchy absorption and delamination of later coats. Stop coarser, and scratches show; go finer, and you risk adhesion failure.

Tools & Materials

• 9×11 in silicon carbide sandpaper sheets: 220, 280, 320
• Soft sanding block for flats; foam pads for curves
• Masking tape for fretboards, binding, and cavities
• Vacuum and tack cloth
• Sealer (vinyl sealer or shellac)
• PPE: respirator, gloves, eye protection

Recommended Grit Progression

• 220 grit — Levels surfaces, removes tool marks.
• 280 grit — Refines scratch field, preps for final pass.
• 320 grit — Final sanding before sealer.

Step-by-Step: Guitar Sanding Workflow

1. Prep the body. Strip old finish if needed, then fill pores. Let filler dry before sanding.
2. Sand at 220. Start with 220 grit (25-pack) to remove scratches and level filler. Always sand with the grain.
3. Refine at 280. Step to 280 grit (50-pack). Erase 220 scratches and prep the surface for the final sanding.
4. Finish at 320. Sand evenly with 320 grit (100-pack). Inspect under raking light for scratches or missed spots.
5. Clean thoroughly. Vacuum and tack every surface. Even tiny dust specks show under gloss finishes.
6. Seal promptly. Apply your chosen sealer. The 320 grit scratches give it perfect mechanical bond.

Special Cases

Maple tops: Highly reflective—take extra care at 320 to avoid cross-scratches.
Open-pored woods (mahogany, ash): Grain-fill before sanding to 320; otherwise pores telegraph through.
Neck sanding: Match the body’s grit—uneven prep causes sheen differences after finish.

Pro Tips

• Always sand with the grain—scratches across figured maple stand out badly.
• Mask bindings carefully to avoid rounding edges with sandpaper.
• Replace paper early—dull sheets polish and reduce adhesion.
• Hold bodies up to raking light—guitar finishes magnify surface flaws.
• Stop at 320—don’t be tempted to “make it smoother” at 400+ before sealer.

Aftercare

• Scuff-sand with 400–600 between sealer coats for bonding.
• Keep humidity controlled—wood movement shows under gloss finishes.
• Touch-ups: sand back to 320 before re-sealing spots.

FAQs

• Can I stop at 220? Not for guitars—scratches show through glossy lacquer.
• Why not sand finer than 320? It risks adhesion failure for sealers and topcoats.
• Is 280 necessary? It helps refine the surface, especially on figured woods, but you can skip straight to 320 if the 220 pass is clean.
• What sealer works best? Vinyl sealer or dewaxed shellac both bond well at 320 scratches.

Video: Guitar Sanding Demo

Closing: For flawless guitar refinishing, sand smart: 220 ? 280 ? 320 grit, clean thoroughly, and seal right away. This prep ensures smooth, even finishes that let your instrument’s beauty shine through.