Smooth Resin Castings: 400?800?1200?2000 Grit

Resin castings—used in jewelry, crafts, or models—often cure with rough edges, bubbles, or dull surfaces. The proven way to refine them is sanding with a grit ladder: 400 ? 800 ? 1200 ? 2000 grit. Each stage reduces imperfections until the surface is ready for polish or clear coat.

Why Sand Resin

Fresh resin often shows layer lines or cloudy spots. Sanding evens the surface, while progressively finer grits eliminate scratches. Without this process, polishing compounds alone can’t achieve true clarity.

Tools & Materials

• 9×11 in wet/dry sandpaper sheets: 400, 800, 1200, 2000 grit
• Foam sanding block
• Spray bottle with water
• Microfiber towels
• Plastic polishing compound
• Buffing pad or drill attachment
• PPE: gloves, respirator, safety glasses

Recommended Grit Sequence

• 400 grit — Levels uneven surfaces, removes casting marks.
• 800 grit — Refines scratches from coarse sanding.
• 1200 grit — Smooths to satin clarity.
• 2000 grit — Pre-polish finish before compound.

Step-by-Step: Resin Casting Sanding

1. Inspect casting. Mark bubbles, seams, or rough spots.
2. Sand at 400 grit. With 400 grit (25-pack), wet-sand until surface is flat and marks fade.
3. Step to 800 grit. Switch to 800 grit (50-pack). Smooth evenly until scratches reduce.
4. Refine at 1200 grit. Use 1200 grit (100-pack) for satin clarity.
5. Final sanding at 2000 grit. Finish with 2000 grit (25-pack) until surface feels slick.
6. Polish. Apply plastic polish with buffing pad until surface shines.
7. Seal. Apply clear coat if long-term protection is desired.

Special Cases

Colored resins: Sand gently to avoid dulling pigments.
Embedded objects: Take care not to expose inclusions while sanding.
Large castings: Use orbital sander for even surface refinement.

Pro Tips

• Always sand wet to prevent heat and clogging.
• Sand in alternating directions each grit for scratch removal.
• Replace paper frequently—resin clogs quickly.
• Don’t skip grits—scratches remain visible under polish.
• Finish with plastic polish or automotive compound for maximum clarity.

Aftercare

• Store resin pieces away from direct sun to prevent yellowing.
• Refresh shine with 2000 grit + polish when surfaces dull.
• Clean only with microfiber and mild soap—avoid abrasives.

FAQs

• Can I stop at 1200 grit? No—resin still looks hazy without 2000 + polish.
• What compound works best? Plastic polishes or automotive rubbing compounds.
• Will sanding weaken resin? Only slightly—removes surface microns if done properly.
• Can epoxy resin be sanded? Yes—same grit sequence works well.

Video: Resin Sanding & Polishing

Closing: Resin castings gain clarity and shine through 400 ? 800 ? 1200 ? 2000 grit sanding. Follow with polish or clear coat for stunning, professional-looking results.