Polishing Metal to a Mirror Finish: Sandpaper Grit Guide

Polished metal surfaces—from stainless steel to aluminum—can look stunning when finished to a mirror shine. Achieving this effect requires the right grit progression and patience. This guide explains how to sand and polish metal step by step for a flawless reflective finish.

Why Sand Metal Before Polishing?

Raw or previously finished metal often has scratches, oxidation, or machining marks. Sanding levels the surface and removes imperfections so polishing compounds can do their job effectively. Without sanding, metal remains dull no matter how much you buff.

Tools You’ll Need

• Wet/dry sandpaper sheets in multiple grits
• Sanding block or orbital sander (optional)
• Water spray bottle
• Polishing compound and buffing wheel (or microfiber cloth)
• Protective gloves and safety glasses

Best Grit Sequence for Polishing Metal

• 400 grit: Removes deep scratches and oxidation.
• 800 grit: Refines sanding marks.
• 1200 grit: Smooths surface to satin finish.
• 2000 grit: Pre-polish clarity.
• 3000 grit: Final sanding before buffing.

Step-by-Step: Sanding & Polishing Metal

1. Initial sanding. Use 400 grit (50-pack) to remove scratches and oxidation.
2. Smooth with 800 grit. Switch to 800 grit (100-pack) for consistent refinement.
3. Refine with 1200 grit. Apply 1200 grit (25-pack) to reduce sanding haze.
4. Pre-polish with 2000 grit. Use 2000 grit (50-pack) for near-mirror smoothness.
5. Final sanding. Finish with 3000 grit (25-pack) before buffing.
6. Buff and polish. Apply polishing compound with a buffing wheel or microfiber cloth until reflective.
7. Seal if needed. Apply protective wax or clear coat to preserve shine.

Special Cases

For stainless steel, always sand in one direction to avoid swirl marks. For aluminum, use light pressure to prevent deep scratches. Brass and copper may require extra polishing to maintain brightness.

Pro Tips

• Always wet sand to avoid overheating the metal.
• Check progress under strong light to spot scratches early.
• Don’t skip grits—each step removes scratches from the previous one.

Aftercare

• Clean polished metal with microfiber cloths only.
• Avoid abrasive cleaners that dull the finish.
• Reapply protective coating periodically for lasting shine.

FAQs

• Can I polish without sanding? No—polishing compound alone can’t remove deep scratches.
• How long does it take? Small items can take an hour, larger panels several hours.
• What if scratches remain after polishing? Repeat sanding with the previous grit until smooth.

Watch & Learn

With the right grit sequence, metal surfaces can be polished to a mirror-like shine. Stock up on 400 to 3000 grit wet/dry sandpaper sheets for your next polishing project.