Sanding Face-Frame Inside Corners: Wedge Blocks and Stroke Control

Face-frame cabinetry looks crisp and professional—but the inside corners where rails meet stiles can easily trap dust and show uneven finish if sanded poorly. The goal is to smooth these intersections without rounding the joints or cutting into the edge profiles. With the right tools and grit pacing, you can create perfect transitions every time.

Why Sanding Matters for Inside Corners

Routered joints and tight grain transitions highlight every sanding flaw. Hand pressure or the wrong block shape can distort square corners, leading to gaps or over-sanded edges visible after staining. Controlled sanding using wedge blocks and proper grit progression maintains crisp geometry while preparing the surface for uniform color and sheen.

Recommended Tools

• Custom wedge sanding blocks (foam or hardwood, 30–45° angles).
• 9×11-inch silicon carbide wet/dry sandpaper sheets.
• Random-orbit sander for flat areas.
• Shop vacuum and tack cloth.
• Raking light for inspection.

Grit Sequence

• 120 grit: Removing milling marks and glue residue.
• 180 grit: Refining the grain for smooth, even tone.
• 320 grit: Final pre-finish polishing and touch-ups.

Step-by-Step: Sanding Inside Corners

1. Prep the surface. Vacuum and wipe down the cabinet frame. Identify tight intersections or areas with excess glue squeeze-out.
2. Shape your sanding block. Cut a small wedge block to match your corner angle. Wrap it with 120 Grit (25-pack) and sand lightly along the joint line to remove high spots.
3. Blend transitions. Switch to 180 Grit (50-pack) paper for refining. Keep the wedge angled slightly away from the joint to avoid rounding the corner.
4. Polish for finishing. Finish with 320 Grit (100-pack) sheets to remove fine scratches. Use gentle strokes, maintaining consistent pressure and direction.
5. Check your work. Shine a raking light across the corner. If one side looks glossier, sand the opposite lightly until the sheen matches.
6. Clean thoroughly. Vacuum and wipe the inside corner to remove any trapped dust before applying finish or primer.

Special Cases

For painted cabinetry, you can stop at 220 grit; for clear-coated wood, finish with 320 grit for maximum clarity. On dark stains, apply a pre-stain conditioner to even out tone where the grain changes direction inside corners.

Pro Tips

• Use a folded paper edge or emery board for narrow grooves under 1/4" wide.
• Never sand cross-grain into an adjoining stile—always follow each piece’s grain direction.
• Mark corner edges lightly with pencil; once lines are gone, sanding is complete.
• Work slowly—corner damage is nearly impossible to fix without refinishing the entire frame.

Aftercare

• Re-sand corners lightly between coats for flawless finish continuity.
• Inspect periodically; dust buildup dulls corner finishes faster than flat areas.
• Keep extra wedge blocks on hand for touch-ups during future repainting or refinishing.

FAQs

• Can I use a power sander? Not in tight corners—hand sanding with wedges gives superior control and prevents rounding.
• What’s the best block material? Soft foam conforms gently; hardwood wedges provide precision for sharper profiles.
• How do I reach deep inset corners? Wrap sandpaper around a paint stir stick or use narrow foam strips.

Watch & Learn

For precise control in detailed sanding, explore eQualle’s fine sanding collection. Premium silicon carbide sheets maintain sharpness and flexibility—ideal for trimming, cabinetry, and intricate joinery work.

Conclusion: Clean, sharp inside corners define professional cabinetry. By following the 120–180–320 grit sequence and using custom wedge blocks, you’ll keep lines crisp, eliminate cross-grain scratches, and achieve a smooth, flawless finish that showcases your craftsmanship.