Feather-Edge Chipped Car Paint: 100–600 Grit Primer-Ready

Rock chips and edge flake around door handles are small but glaring. If you simply dab touch-up over a sharp paint crater, the ring will show forever. The fix is feather-edging: sanding the damaged spot so the broken paint edge transitions smoothly into surrounding layers, then priming and recoating. Here’s a clean, repeatable process that gets you from chip to primer-ready using a tight grit ladder and smart surface checks—no witness lines, no telegraphed rings.

Why Sanding (Feather-Edging) Matters

Automotive paint is a stack: substrate (steel/aluminum/plastic), corrosion protection, primer, base color, and clear. A chip leaves a step down through that stack. If you don’t flatten the step into a gentle ramp, new coatings bridge it and shrink back, revealing a halo. Proper sanding (1) levels sharp paint edges without gouging the substrate, (2) creates a uniform scratch field the primer can grip, and (3) preps for filler or glazing only where it’s actually needed. The goal is invisible repair under base/clear—not just smooth-to-the-touch.

Tools & Supplies

• Hand blocks: one firm, flat mini block (1–3 in.) and a soft foam pad for gentle crown areas.
• Optional 2–3 in. DA (random-orbit) sander at low speed for larger blends; hand control is safer around chips.
• Wet/dry silicon-carbide sandpaper sheets: 100, 180, 600 (optional 800–1000 wet before basecoat on large panels).
• Panel wipe/dewaxer (isopropyl or dedicated solvent), clean microfiber towels.
• Guide coat (dry powder or mist), plastic masking, tape, and paper.
• Glazing putty (polyester finishing glaze) for micro-low spots; 2K primer-surfacer compatible with your system.
• Raking/inspection light and pencil for witness marks.
• PPE: respirator, eye protection, gloves; work in a ventilated area.

Recommended Grit Sequence

• 100 grit: Initial cut to knock down sharp paint lips and remove loose edges quickly, controlled by hand.
• 180 grit: Feather and refine the crater transition into surrounding paint without cutting too deep.
• 600 grit (wet or dry): Pre-primer refinement and final scuff before primer; optional 800–1000 wet just before basecoat on larger blends.

Step-by-Step: From Chip to Primer-Ready

1. Clean and de-wax. Wash the area and wipe with panel wipe. Waxes and road films smear under paper and can cause fisheyes later. Mask trim edges nearby to keep sanding tight.
2. Inspect & mark. Under raking light, pencil a faint ring around the chip’s outer halo. This will help you track how far you feather. If there’s rust (on steel), plan to remove it fully; if the chip exposes plastic (bumper cover), note the substrate.
3. Knock down the paint lip at 100. Wrap a small, firm block with 100 Grit (25-pack) and make short, controlled strokes across the chip edge—never grind in circles with fingertip pressure. Your goal is to lower the high edge, not excavate the center. Keep the block flat to avoid digging valleys.
4. Widen the feather gently. As the sharp edge softens, widen your passes just beyond the pencil ring so the transition spreads over a larger, more forgiving area. Re-mark if needed to avoid drifting too far.
5. Refine and true the ramp at 180. Switch to a fresh sheet of 180 Grit (50-pack). Slightly change your stroke direction so any leftover 100 scratches show under light. Use feather-light pressure; let grit do the work. Stop when you can’t feel a step with a fingernail and the feather looks like a slow, even fade.
6. Guide coat to proof the feather. Dust on guide coat and make a couple of long 180 passes. Any stubborn dark ring indicates a high edge or low crater you missed. Knock remaining highs lightly; if you still see a low center, plan a thin glazing putty skim.
7. Glaze only if necessary. Mix a thin skim of glazing putty over the crater center and out onto the feather just a bit. After cure, block at 180 using the same direction as your feather to avoid creating cross-waves. Reapply guide coat and check again.
8. Pre-primer scuff at 600. Once the feather and glaze (if used) are correct, step to 600 Grit (100-pack). Dry or wet works here; wet cuts cooler on larger blends. Scuff the entire repair halo plus a few extra inches so primer has uniform tooth.
9. Prime smart. Apply 2–3 thin coats of a compatible 2K primer-surfacer, extending just beyond the feathered area. Allow to cure to sandable. Dust on guide coat again.
10. Block the primer. Level with 600 (wet) on a soft pad for curves and a firm mini-block on flats. If you break through to color in a few spots, that’s okay; you’re truing the surface. For large blends headed to base/clear now, you can refine primer edges to 800–1000 wet before color.
11. Final clean and coat. Rinse, dry, and panel-wipe. Tack lightly. Proceed with basecoat/clear per your system (blend the base beyond the repair, then clear over the full blend zone or panel).

Special Cases

Rusty steel chips: Remove all rust to bright metal (use a rust eraser, 120–180 by hand, or a small spot blaster), then apply an epoxy or etch primer before 2K surfacer. Don’t trap rust under glaze/primer.
Aluminum panels: Avoid coarse gouges at 100—aluminum marks easily. Keep pressure light and move to 180 sooner. Use epoxy primer for best adhesion/corrosion protection.
Plastic bumper covers: Chips often undercut the color/clear. Keep pressure light to avoid melting or smearing plastics. Use an adhesion promoter before primer on exposed plastic.
Single-stage paint: Feather the color just like base/clear, but expect stronger dye transfer onto paper. Keep sheets fresh and pressure low.

Pro Tips

• Block, don’t finger-sand. Finger pressure creates ruts that telegraph under clear. Use a mini-block for control.
• Let the grit do it. Dull paper + pressure = heat, smearing, and waves. Rotate to a fresh section early.
• Guide coat is your truth serum. If you still see a dark ring after 180, the edge is high or the center is low—fix it now, not after paint.
• Feather with the panel flow. Keep strokes aligned with the body line; cross-grain arcs read under reflections.
• Keep the repair small. Only widen as needed for a smooth ramp. Oversized blends mean more paint and more risk.
• Mind recoat windows. Follow primer/base/clear timing strictly for adhesion and gloss holdout.

Aftercare

• Let clear fully cure before aggressive washing or polishing. Many systems need several days for hardness.
• For minor dust nibs after full cure, wet-sand locally with 1500–2000 and polish.
• Wash with pH-neutral soap; avoid harsh chemicals on fresh paint.
• Address future chips promptly: de-wax, 600 scuff, and touch up, or repeat the feather/prime routine for larger damage.

FAQs

• Can I start at 120 instead of 100? Yes—on small, shallow chips. If the edge is stubborn, drop briefly to 100 and then return to 180.
• Do I have to glaze? Only if a low remains after feathering. Use the thinnest skim possible and block it with 180.
• Dry or wet at 600? Either. Wet cuts cooler and keeps dust down on large blends; dry is fine for small repairs if you clean well.
• Do I need epoxy primer on bare metal? Best practice on steel/aluminum exposures is a thin epoxy or etch, then 2K surfacer.
• Why did a ring appear after clear? The feather wasn’t fully blended (leftover high edge) or primer shrank. Re-feather, re-prime, and ensure full cure before topcoats.

Watch & Learn

Closing: Invisible chip repair is a process, not a product. Keep your ladder simple—100 → 180 → 600—prove the feather with guide coat, glaze only if needed, and prime smart. Stock the specific sheets so you execute consistently: knock down edges with 100 (25-pack), refine the ramp with 180 (50-pack), and scuff to primer-ready with 600 (100-pack). Do that, and the halo stays gone after the shine comes back.