De-Nib Varnish & Lacquer: 320–600 Grit for Glassy Coats

Little dust nibs, tiny raised fibers, and the occasional brush trail can keep even a good varnish or lacquer job from feeling silky. The fix isn’t a heavy cut—it’s a light, controlled de-nib between coats. This guide shows you a clean, repeatable process using a tight grit ladder—320 → 400 → 600—so your next coat lays flatter, flashes evenly, and buffs to a deep, mirror finish.

Why De-Nibbing Matters

Clear coats are truth tellers. As they cure, airborne dust lands; as they stack, micro-texture accumulates. If you keep recoating without flattening nibs, you trap defects that telegraph under gloss. A disciplined de-nib: (1) levels nibs and slight orange peel into a uniform plane, (2) tightens the scratch field so the next coat wets out smoothly, and (3) prevents adhesion issues by removing surface contaminants between coats. The key is timing: the coat must be sandable (it should powder)—if it smears, wait.

Tools You’ll Need

• Hand sanding block (firm face) for flats; thin foam hand pad for profiles and edges.
• Random-orbit (DA) sander (optional) at low speed for large, flat panels.
• Wet/dry sheets: 320, 400, 600 (silicon carbide or AlOx).
• Vacuum/dust extractor, microfiber towels, and a light tack cloth.
• Raking/inspection light and a pencil for faint witness marks.
• Painter’s tape to protect crisp arrises and adjacent parts.
• PPE: respirator (P100), eye protection; good ventilation.

Recommended Grit Sequence

• 320 grit: Primary de-nib on cured varnish/lacquer; removes dust specks and slight texture quickly.
• 400 grit: Refinement for show surfaces and higher-gloss systems.
• 600 grit: Optional whisper pass before the final coat for a near-spray feel.

Step-by-Step: Silky Between-Coat Sanding

1. Do the powder test. In a hidden corner, make 3–4 strokes with 320. If the finish powders, it’s ready. If it smears or balls, let it cure longer. Humidity and heavy coats extend sand times.
2. Protect edges & map the panel. Tape knife-sharp arrises. Under raking light, pencil a faint crosshatch—witness marks tell you when each grit has finished its job so you don’t over-sand.
3. Primary de-nib at 320. Wrap a firm block with 320 Grit (25-pack). Use feather-light pressure and long, overlapping, with-grain strokes. On big tabletops/doors you can use a DA at low speed with a thin interface pad—keep the pad dead-flat. Goal: erase nibs and soften slight stipple, not cut through.
4. Clean & inspect. Vacuum in two directions and wipe with a clean microfiber. Under raking light, the surface should read uniform satin with no shiny dust bumps or ridges.
5. Refine at 400 (show faces). For piano-gloss trim, cabinet doors, and table tops, take a brief pass with 400 Grit (50-pack). Change your stroke direction slightly (then finish with the grain) so any leftover 320 tracks pop and disappear.
6. Optional glass-up at 600. Right before the final coat, kiss the surface by hand with 600 Grit (100-pack). Two or three light passes are enough to tighten the scratch field for a super-level last coat.
7. Clean impeccably. Vacuum again and lightly tack. Any dust left behind becomes rogue coarse grit under your brush/sprayer, creating fresh nibs.
8. Recoat smart. Apply thin, even coats. Maintain a wet edge. Waterborne lacquer/varnish sets fast—avoid over-brushing. Oil-modified varnish flows longer but needs longer sand times.

Special Cases

Brushed oil-modified varnish: Let it harden fully before 320 (powder test!). If brush lines persist, de-nib at 320 on a firm block, then 400 to refine. Avoid high speed—heat can print smears.
Pre-cat/NC lacquer: Often sandable sooner; keep pressure light to prevent witness lines. If you’re burnishing (surface shines while sanding), swap to fresh paper and back off pressure.
Waterborne clears: Very responsive to 320–400 once truly sandable; keep the room clean and de-dust aggressively—these films show contamination quickly.
High-build pore-filled finishes: Use 400–600 gently. You’re shaving nibs, not re-leveling the entire build.

Pro Tips

• Powder = go, smear = no. If it doesn’t powder, you’re not de-nibbing—you’re dragging and risk witness marks.
• Block the flats, pad the profiles. Firm block delivers the flattest plane; thin foam pad for beads/ogees with counted strokes.
• Fresh sheets beat pressure. When cut slows, rotate to a new quadrant—pressure creates heat and haze.
• Alternate directions. A slight diagonal at 320, then finish with the grain at 400/600 to expose leftovers instantly.
• Edge discipline. Do edges by hand with the current grit—two light strokes only. Most cut-throughs start at corners.

Aftercare

• Respect recoat windows and room conditions (temp/RH) for best flow and cure.
• Let the final coat cure fully before heavy handling or rubbing.
• For rub-out after full cure, 1500–3000 wet plus compound can produce mirror gloss—keep it cool and clean.
• Store abrasives flat and clean; label “finish-only” sheets to avoid cross-contamination from wood dust.

FAQs

• Do I have to sand between every coat? For the smoothest results, yes—at least a quick 320 de-nib after each sandable coat.
• Will 600 reduce adhesion? Used lightly just before the last coat, 600 simply tightens the scratch field. Don’t burnish with pressure.
• Can I wet-sand between coats? Generally avoid water between coats on wood; moisture can raise grain at edges. Keep it dry for inter-coat de-nibbing; save wet steps for post-cure rub-out.
• Paper or mesh? Either works. Mesh extracts dust well; paper often leaves a slightly tighter scratch at fine grits. Technique matters most.
• Why do I see shiny patches after sanding? Those spots weren’t touched—go back lightly at the current grit until sheen is uniform satin, then climb.

Watch & Learn

Closing: De-nibbing is about touch and timing, not force. Wait for a true powdering response, then run a tight ladder—320 to knock nibs (25-pack), 400 to refine for show surfaces (50-pack), and an optional whisper of 600 before your last coat (100-pack). Keep pressure light, sheets fresh, and dust at bay—and your clear coats will lay down flat, glossy, and clean.