Sanding Resin Projects: From Rough Casting to Glossy Finish

Resin art and casting can create stunning pieces, but fresh out of the mold, resin often has rough edges, scratches, or a cloudy surface. Sanding is the key to transforming rough resin into a smooth, glass-like finish. Here’s how to sand resin projects step by step with the right grit sequence.

Why Sand Resin?

Even with careful pouring, resin may cure with sharp edges, surface imperfections, or air bubbles. Sanding levels the surface, removes scratches, and prepares resin for polishing or coating. Skipping sanding leaves your piece looking dull instead of crystal clear.

Recommended Tools

• Wet/dry silicon carbide sandpaper sheets
• Soft sanding block or foam pad
• Spray bottle with water and mild soap
• Microfiber cloths
• Polishing compound or resin polish

Choosing the Right Grit Sequence

• 400 grit: Removes casting marks and sharp edges.
• 800 grit: Smooths out scratches left by coarse sanding.
• 1500 grit: Refines the surface before final finishing.
• 2000–3000 grit: Prepares resin for polishing to a glossy finish.

Step-by-Step: Sanding Resin

1. Start with 400 grit. Wet sand the entire piece to remove sharp edges and rough areas. A good option is 400 grit (25-pack).
2. Move to 800 grit. Smooth and refine with 800 grit (50-pack), keeping the surface wet to prevent clogging.
3. Continue with 1500 grit. Further refine the resin using 1500 grit (100-pack) for a nearly clear finish.
4. Finish with 2000–3000 grit. Achieve a polish-ready surface using ultra-fine sheets. 2000 grit (100-pack) is perfect here.
5. Polish to clarity. Apply resin polish with a microfiber cloth or buffing wheel for a glossy, professional look.

Special Cases

Jewelry pieces: Small items may need hand-sanding with folded sheets.
Large resin tables: Use a random orbital sander with wet/dry discs for efficiency.
Colored or tinted resin: Sand gently—scratches can alter the way light passes through the piece.

Pro Tips

• Always wet sand resin to avoid heat buildup and dust.
• Work through every grit in sequence—skipping grits leaves visible scratches.
• Use overlapping strokes for consistent results.

Aftercare & Next Steps

• Seal with a resin topcoat if desired for added protection.
• Store polished resin away from direct sunlight to prevent yellowing.
• Keep leftover sandpaper dry and flat for your next project.

FAQs

• Can I dry sand resin? Not recommended—dust is hazardous and heat can cause melting.
• How do I know when to move to the next grit? When scratches from the previous grit are fully removed.
• Do I need to polish after sanding? For a crystal-clear finish, yes. Sanding alone won’t achieve full clarity.

Watch & Learn

Sanding resin may take patience, but the results are worth it. With the right grit sequence, you can turn cloudy, scratched resin into a smooth, glossy surface that shines like glass.