Sanding Wood Slabs for Clear Epoxy Casting

Wood slabs paired with clear epoxy create striking tabletops and art pieces. But sanding before casting is critical—any roughness, dirt, or unevenness will show through the epoxy. This guide explains how to sand slabs properly to prepare them for flawless clear epoxy pours.

Why Pre-Cast Sanding Matters

Epoxy highlights every surface detail. If slabs aren’t sanded smooth and level, bubbles, voids, or cloudy spots may appear in the final piece. Proper sanding ensures epoxy bonds evenly and cures crystal clear.

Tools You’ll Need

• Random orbital sander or drum sander
• Hand sanding block for edges
• Wet/dry sandpaper sheets (80–220 grit)
• Vacuum and tack cloth
• Leveling tools and clamps

Best Grit Sequence for Slab Prep

• 80 grit: Flattens surfaces and removes saw marks.
• 150 grit: Smooths wood while keeping natural character.
• 220 grit: Prepares surfaces for strong epoxy adhesion.

Step-by-Step: Sanding for Epoxy Casting

1. Flatten slabs. Use 80 grit (25-pack) to level the wood and remove saw marks.
2. Smooth transitions. Switch to 150 grit (50-pack) for general smoothing.
3. Final prep. Sand with 220 grit (100-pack) to create a clean, epoxy-ready surface.
4. Clean thoroughly. Vacuum and tack cloth to remove dust before pouring epoxy.
5. Seal edges. Apply a thin epoxy seal coat after sanding to prevent air bubbles during casting.

Special Cases

For slabs with bark edges, lightly sand with 150 grit to stabilize fibers while preserving natural look. If cracks exist, fill them with epoxy or CA glue before final sanding.

Pro Tips

• Sand both sides to balance and prevent warping.
• Always check slab flatness with a straightedge before casting.
• Seal coat prevents air bubbles from escaping wood pores during casting.

Aftercare

• Re-sand lightly: After curing, wet sand epoxy with higher grits for polishing.
• Buff & polish: Use polishing compounds for glass-like clarity.
• Protect surface: Avoid direct heat or sunlight that may yellow epoxy.

FAQs

• Can I pour epoxy without sanding? No—rough or dirty wood compromises adhesion and clarity.
• Do I need to sand after sealing? Yes, lightly scuff sand to remove dust nibs before the final pour.
• What grit works best before epoxy? 220 grit provides the ideal tooth for bonding without scratches showing.

Watch & Learn

Sanding wood slabs properly ensures epoxy bonds smoothly and cures crystal clear. With the right grit sequence and prep, your slab-and-epoxy projects will look stunning and last for years.