Prevent Burn-Through on Edge-Banded Plywood: Grit Ceilings & Blocks

Edge banding makes plywood look like solid wood—until sanding goes a hair too far and exposes glue lines or the paper-thin face veneer. Preventing burn-through is about control: set conservative grit ceilings, use hard backers, and separate your workflows for banding and faces. Here’s the no-drama approach that keeps edges flush and veneers intact.

Why sanding matters

Plywood face veneers are often 0.3–0.6 mm thick. A few careless passes with a soft pad can roll over edges or telegraph the banding seam. Smart sanding keeps pressure off the veneer near the seam, flushes the banding mechanically first, and uses just enough grit to prep for finish without polishing the glue line.

Tools you’ll need

• Flush-trim bit and light hand plane or cabinet scraper (to reduce sanding on the banding).
• Hard-back sanding block, plus a random-orbit sander with firm pad and dust extraction.
• 9×11 in silicon carbide sheets: 120, 180, 220 (wet/dry used dry).
• Low-tack masking tape for edge protection, raking light, and a pencil for witness marks.
• Vacuum with brush, microfiber or tack cloths.

Recommended grit sequence

• 120 grit: Primary prep for faces and gentle flush-sand on banding after mechanical flush.
• 180 grit: Blend and refine; remove 120 lines without closing pores.
• 220 grit (ceiling): Final pre-finish pass for clear coats or paint; avoid going finer on veneers to reduce burnish risk.

Going finer than 220 on many veneers risks glue-line polish and adhesion issues for waterborne finishes.

Step-by-step

1. Mechanically flush the banding first. Use a sharp flush-trim bit to within a whisper, then finish with a cabinet scraper or light block plane. Fewer sanding passes mean less risk. Avoid rocking—keep the sole flat on the plywood face, not the banding alone.
2. Tape a guard lane. Run low-tack tape 1–2 mm onto the face veneer along the seam. This visual fence reminds you to keep pressure on the banding, not the veneer, during early sanding.
3. Initial sanding at 120 (banding focus). With a hard block and fresh sheet, make short strokes across the banding only to kiss it perfectly flush, then a couple of with-grain strokes that barely touch the veneer. For powered blending of broad areas, switch to 120 Grit Sandpaper (25-pack) on a firm-pad RO, but keep dwell time near the seam extremely short.
4. Face prep at 180 (with the grain). Remove the tape. Make full-face, even passes with the RO or a wide block to unify the scratch pattern, pausing early near seams. This is where 180 Grit Sandpaper (50-pack) cleans up the 120 without erasing veneer thickness.
5. Ceiling at 220 (selective, light). Do a quick, uniform pass to even sheen and stop. On edges and corners, switch to hand block and use two or three light strokes only. For a finish-ready surface that keeps the glue line invisible, cap with 220 Grit Sandpaper (100-pack).
6. Arris control. Crisp edges look intentional. Never roll the sander over the edge; instead, hold a 45° block for one or two light strokes to micro-ease without rounding.
7. Raking-light QC and solvent reveal. HEPA-vac, then wipe a small panel area with mineral spirits to preview finish clarity. If a seam telegraphs, spot-sand the banding with 180 (block) and re-check.

Special cases

Ultra-thin veneers: Skip 120 on faces entirely; scrape/plane the banding and start your sanding at 180 with a hard block, saving 220 for a brief unifying pass.

Pre-finished banding: Scuff with 180 only; aggressive grits can break through the factory layer and reveal glue lines.

Paint-grade panels: You can linger a touch longer at 220, but avoid polishing; primer needs tooth. If you see shine, lightly backstep to 180.

Pro tips

• Pencil a light witness line across the seam; stop sanding as soon as it disappears uniformly.
• Keep pads and blocks hard near seams; soft pads roll and round edges, causing burn-through and telegraphing.
• Replace sheets early; dull paper skates and forces extra passes—exactly what you’re trying to avoid.
• Control heat. Heat softens glue lines and can create a halo. Use moderate speed and light pressure.
• Always sand faces and edges as separate workflows; never try to flush the banding while making full-face passes.

Aftercare

• Final vacuum and tack wipe. Avoid heavy solvent wipes right before waterborne finishes.
• For stain, test on an offcut with matching banding; if the seam telegraphs, consider a thin sealer coat before color.
• Between coats, scuff 320 with the grain on flats only; hand-block edges to preserve crisp lines.

FAQs

• Why not 100 or coarser? Coarse grits remove veneer too quickly and leave deep scratches that require extra passes to clear—raising burn-through risk.
• Can I go finer than 220? Usually unnecessary on veneer before finish; save finer work for between-coat rub-outs.
• Do I need a soft pad anywhere? Only for very slight crown blending, and never directly on the seam.

Video

Closing

Burn-through prevention is restraint plus technique. Mechanically flush the banding, use hard backers, cap your grits at 220, and separate your edge work from face prep. With crisp edges and a uniform scratch pattern, edge-banded panels finish like solid wood—no seams, no halos, no surprises.