How to Polish Polycarbonate Visors and Lenses: Scratch Depth Check Before Sanding (800–3000 Grit Guide)

Polycarbonate visors, helmet shields, and machine guards often collect scratches that scatter light and obscure vision. Before sanding, it’s crucial to assess scratch depth—removing too much material can distort optics. This guide shows how to evaluate, sand, and polish polycarbonate for a distortion-free, crystal-clear surface.

Why Scratch Depth Assessment Matters

Unlike acrylic, polycarbonate is softer and flexes under pressure. Deep sanding can thin or warp the part, especially on curved visors. Measuring scratch depth first ensures you use only the minimum abrasion needed to restore clarity while keeping thickness uniform.

Recommended Tools

• Magnifier or bright raking light for inspection.
• Wet/dry sandpaper sheets.
• Soft foam sanding pad or block.
• Plastic-safe polish and microfiber cloths.
• Spray bottle with clean water.

Best Grit Sequence for Polycarbonate Repair

• 800 grit: removes moderate surface haze and fine scratches.
• 1500 grit: blends and refines the sanded area.
• 3000 grit: final pre-polish stage before compound.

Step-by-Step: Restoring Clarity Safely

1. Inspect under raking light. Mark scratches with a washable pen. If your fingernail catches, it’s deep—consider replacement instead of sanding.
2. Clean thoroughly. Wash with mild soap and dry using a microfiber cloth.
3. Wet-sand with 800 grit. Use gentle, linear strokes following visor curvature. Keep the surface soaked to prevent heat buildup.
4. Progress to 1500 grit. Sand crosswise to the previous pattern until uniform haze appears.
5. Finish with 3000 grit. Light pressure only—goal is semi-gloss clarity, not full shine yet.
6. Polish. Apply plastic polish or fine rubbing compound using circular motions until crystal clear. Buff dry.
7. Inspect optics. Look through the visor at printed text—lines should appear undistorted. Re-sand only if uneven clarity remains.

Special Cases

Mirrored or coated visors should never be sanded on the coated side; restore only the inner surface or replace the visor. For flat machine guards, use a sanding block to maintain optical flatness.

Pro Tips

• Always sand wet to avoid heat clouding.
• Rinse paper often—loaded grit scratches instantly.
• Do not use solvent cleaners like acetone or alcohol; they craze polycarbonate.

Aftercare

• Apply anti-fog or anti-scratch coatings after polishing.
• Clean only with water and mild detergent—no ammonia glass cleaners.
• Store visors in a soft pouch to prevent new micro-scratches.

FAQs

• Can I start at 400 grit for deep scratches? Only if you’re prepared to re-sand through every finer stage to 3000; it removes material quickly.
• Why does the surface look foggy after 1500 grit? It has uniform micro-haze—clarity returns after 3000 grit and polish.
• Can I buff with a power tool? Yes, at low speed and light pressure only; polycarbonate softens around 120 °C (250 °F).

Watch & Learn

Stock your bench: get fine and super-fine grits in 25-sheet packs for safe, optically clear polycarbonate restoration projects.